Bosch Appliances Water Heater GWH 1000 User Manual

MODEL GWH 1000 P  
INDOOR MODEL  
Standing pilot  
Suitable for heating potable water only  
Not approved for space heating or preheated water applications  
MODEL GWH 1000 P NG - Natural Gas  
MODEL GWH 1000 P LP - Liquefied Petroleum (LP) Gas  
Warning: If the information in this manual is not  
followed exactly, a fire or explosion may result  
causing property damage, personal injury or death.  
Do not store or use gasoline or other flammable  
vapor and liquids in the vicinity of this or any other  
appliance.  
Improper installation, adjustment, alteration, service  
or maintenance can cause injury or property  
damage. Refer to this manual. For assistance or  
additional information consult a qualified installer,  
service agency or the gas supplier.  
What to do if you smell gas  
Open windows.  
Close gas valve.  
Do not try to light any appliance.  
Do not touch any electrical switch; do not use any  
phone in your building.  
Immediately call your gas supplier from a neighbor’s  
phone. Follow the gas supplier’s instructions.  
If you cannot reach your gas supplier, call the fire  
department.  
In the Commonwealth of Massachusettes the  
installation must be performed by a licensed  
plumber or gas fitter.  
Installation and service must be performed by a  
qualified installer, service agency or the gas supplier  
.
Upon completion of the installation, these  
instructions should be handed to the user of the  
appliance for future reference.  
 
Appliance details  
2
Appliance details  
Dimensions  
2.1 GWH 1000 P specifications  
(Technical data)  
Depth (in): 8.66” (220 mm)  
Width (in): 12.20” (310 mm)  
Height (in): 22.83” (580 mm)  
Weight: 26 pounds (12 kg).  
Approved in US/Canada  
Capacity  
GWH 1000 P: 2.6 GPM  
Gas types  
Maximum output  
Natural Gas  
LP Gas  
GWH 1000 P: 58 400 Btu/hr  
Maximum input  
Safety devices  
GWH 1000 P: 74 900 Btu/hr  
Flame failure device (ionization thermocouple)  
Pressure relief valve (supplied with heater)  
Over heat prevention (temperature limiter).  
Efficiency in %  
Recovery efficiency 78%  
Min. Output  
Water resistant  
GWH 1000 P: 23 906 Btu/hr  
IP X4.  
Gas Requirement  
Gas connection (inches) - ½” NPT  
Inlet gas pressure under maximum operation*  
Propane: 10.5” - 14” water column  
Natural Gas: 5.7” - 14” water column.  
* To measure Gas Pressure, see Measuring Gas  
Pressure, chapter 3.8.  
Venting  
Natural Draft  
Vent diameter (inches) - 4”  
Minimum height (feet) - 6’ with no elbows  
Vertical termination.  
Water  
Hot water connection (inches) - ½” NPT  
Cold water connection (inches) - ½” NPT  
Water valve material: Polymer (PPS) (Polypropylene  
Sulfid)  
Minimum water flow: 0.5 gallon/minute (1.9 l/m)  
Minimum recommended water pressure: 13 PSI  
(0.9bar)  
Connections:  
– Bottom of heater  
3
6 720 608 124  
 
Appliance details  
2.2 Unpacking the GWH 1000 P heater  
2.3 General rules to follow for safe  
operation  
This heater is packed securely.  
1. You should follow these instructions when you  
install your heater. In the United States: The  
installation must conform with local codes or, in the  
absence of local codes, the National Fuel Gas Code  
ANSI Z223.1/NFPA 54.  
Before installing the unit, be certain you have the  
correct heater for your type of Gas - Propane or  
Natural Gas. Identification labels are found on the  
shipping box, and on the rating plate which is located on  
the right side panel of the cover.  
In Canada: The Installation should conform with  
CGA B149.(1,2) INSTALLATION CODES and /or  
local installation codes  
2. Carefully plan where you install the heater. Proper  
clearances must be followed  
3. The appliance must be isolated from the gas  
supply piping system by closing its individual manual  
gas shutoff valve (not supplied with heater) during  
any pressure testing at pressures in excess of ½ Psig  
(3.5 kPa).  
The appliance and its gas connection must be leak  
tested before placing the appliance in operation.  
4. Keep water heater area clear and free from  
combustibles and flammable liquids. Do not locate  
the heater over any material which might burn.  
Fig. 2 Rating plate  
A
B
Serial number  
Type of gas  
5. Correct gas pressure is critical for the optimum  
operation of this heater. Gas piping must be sized to  
provide the required pressure at the maximum output  
of the heater, while all the other gas appliances are in  
operation. Check with your local gas supplier, and  
see chapter 3.7 and 3.8 to verify proper gas line  
sizing.  
The box includes:  
Pressure relief valve  
Mounting screws  
Product registration card  
Installation manual  
6. Should overheating occur or the gas supply fail to  
shut off, turn off the gas supply at the manual gas  
shut off valve, on the gas line. Note: manual gas  
shutoff valve is not supplied with the heater  
Incandescent particle tray.  
Do not lose this manual, there is a charge for a  
replacement.  
Please complete and return the enclosed product  
registration card.  
7. Do not use this appliance if any part has been  
underwater. Immediately call a qualified service  
technician to inspect the appliance and to replace  
any part of the control system and any gas control  
which has been underwater.  
The GWH 1000 P is not approved or designed for:  
Manufactured (mobile) homes, RV's or boats  
Heating or other recirculating/pumping applications*  
Solar/preheat backup or high temperature booster  
use  
BOSCH is constantly improving its  
products, therefore specifications are  
subject to change without prior notice.  
i
Installation in a bathroom or other occupied rooms  
normally kept closed.  
* This includes domestic hot water circulator pump loop  
systems that may be installed in home hot water system  
prior to installing this unit. An approved recirculation  
design can be found in chapter 3.10.  
4
6 720 608 124  
 
Appliance details  
2.4 Dimensions and installation clearances  
Fig. 3 Dimensions in Inches and (mm)  
4
5
Heat exchanger  
Burner  
Dimensions inches  
(mm)  
10  
11  
20  
26  
36  
37  
38  
39  
40  
49  
102  
Temperature control  
Water valve  
Gas connection  
Output control  
GWH 1000 P  
12.20” (310)  
22.83” (580)  
9” (228)  
Front cover  
A
B
C
D
E
F
Hole for fixing to wall  
Exhaust pipe to connector  
Draft diverter with flue gas monitor  
Gas valve  
Observation window  
Piezo  
4” (100)  
20.71” (526)  
2.36” (60)  
1” (25)  
G
H
1/2”  
Table 1 Dimensions in inches (mm)  
Model GWH 1000  
12 inches (306 mm)  
4 inches (100 mm)  
0 inches  
TOP (A)  
FRONT (B)  
BACK  
SIDES  
4 inches (100 mm)  
12 inches (306 mm)  
BOTTOM (C)  
Fig. 4 Minimum clearances  
5
6 720 608 124  
 
Installation instructions  
3
Installation instructions  
3.1 Introduction  
Warning: The heater must be isolated  
from the gas supply piping system  
during any pressure testing of that  
system at test pressures equal to or  
more than 0.5 psig.  
Please follow these instructions. Failure to follow  
instructions may result in:  
B Damage or injury.  
B Improper operation.  
B Loss of warranty.  
Warning: Place the heater in a location  
where water leaks will do NO DAMAGE  
to adjacent areas.  
If you are unable to perform the tasks required to install  
this heater properly, please contact a locally licensed  
plumber or gas technician.  
Please contact Bosch Water Heating with any  
questions.  
3.3 Heater placement and clearances  
The GWH 1000 P is design certified for installation on  
a combustible wall (see 3.4 Mounting installation)  
provided the wall is not covered with carpet or other  
fabric material. For installations in an alcove or closet,  
maintain the minimum clearances to combustible and  
non-combustible materials listed below. See also Fig. 4.  
3.2 Proper location for installing your  
heater  
Carefully select the location of the water heater. For  
your safety and for proper heater operation, you must  
provide combustion air to the heater and a proper  
exhaust vent system.  
A. Top 12 inches (306 mm)  
B. Front 4 inches (100 mm)  
C. Back 0 inches  
Follow the guidelines below:  
B 1. Locate the heater where venting, gas and  
D. Sides 4 inches (100 mm)  
E. Bottom 12 inches (306 mm)  
plumbing connections are feasible and convenient.  
B 2. The hot water lines should be kept short to save  
energy. Centrally locating the water heater is best. It  
is always best to have hot water lines insulated.  
Warning: The water in this water  
heater is cold and always remains cold  
except for the times that hot water is  
being used. DO NOT INSTALL IN AN  
AREA WHERE IT COULD FREEZE.  
Drain the heater entirely if freezing  
temperatures are anticipated in area  
where heater is installed. See chapter  
4.5 for draining instructions.  
To prevent freeze damage from residual  
water in the heater, introduce short  
bursts of compressed air (20-40psi)  
through these connections to remove  
the residual water in the horizontal  
pipes and water valve.  
Warning:  
Flammable  
materials,  
gasoline, pressurized containers, or any  
other items or articles that are potential  
fire hazards must NOT be placed on or  
adjacent to the heater. The appliance  
area must be kept free of all  
combustible materials, gasoline and  
other flammable vapors and liquids.  
6
6 720 608 124  
 
Installation instructions  
3.4 Mounting Heater  
Warning: before starting installation:  
B check that there are no loose parts  
inside the appliance  
B ensure that gas pipe, gas valve, and  
burner have no damage and are  
properly fitted.  
B Read chapter 2.2 to verify proper gas  
type and to check all parts are included  
in box.  
Front cover should be removed in order to  
inspect components visually (see  
instructions below).  
i
Fig. 6 Remove front cover  
Remove cover and inspect.  
B Remove the temperature control.  
B Remove the outer case by pulling it forwards and  
then lifting upwards.  
B Ensure that the flue terminal is clear.  
B After inspection, replace front cover.  
Install incandescent particle tray.  
B Install incandenscent particle tray using screws  
provided as shown in Fig. 5.  
Fig. 7 Support board  
Screws  
Incandescent particle tray  
Fig. 5 Incandescent particle tray illustration  
Mounting heater.  
The GWH 1000 P is design certified for mounting on a  
wall.  
Warning:  
B Do not install this appliance on a  
carpeted wall.  
The heater must be mounted on a wall using  
appropriate anchoring materials. If wall is a stud wall  
sheathed with plasterboard, it is recommended that  
support board(s), either 1x4’s or 1/2" (minimum)  
plywood first be attached across a pair of studs and  
then the heater should be attached to the support  
boards, see Fig. 7.  
B Secure the two included L shaped hooks to wall  
Fig. 8 Secure heater to wall  
studs or support board 13 1/4” apart. (See Fig. 7).  
B Hang heater on two L shaped hooks. (See Fig. 8).  
7
6 720 608 124  
 
Installation instructions  
Fuel Gas Code for complete information. In buildings of  
tight construction all air should be taken from outside.  
3.5 Combustion air requirements  
The AquaStar water heater holds cold water in its  
copper heat exchanger and water valve when not in use.  
Because of this, any cold air that comes down through  
the unit's vent pipe is capable of freezing these  
components. This Installation Manual specifies the  
minimum vertical vent pipe and the amount of  
combustion air required for this unit. When all  
requirements are followed, the unit will operate properly  
and safely. However, there may still be a risk of freezing  
due to negative draft if all the combustion appliances in  
the building or structure are not being supplied with a  
sufficient amount of make-up air. A wood stove or  
furnace can pull outside air down through the  
Aquastar's vent pipe and across the heat exchanger  
tubing. If the air is cold enough, the heat exchanger is at  
risk of freezing and bursting. Supplying more  
combustion air for all combustion appliances is the  
solution. Follow the instruction on venting and checking  
the adequacy of make up air. A HVAC specialist should  
be consulted on how to provide more combustion air if  
necessary. Observe the following instructions  
concerning combustion air.  
Appliances located in unconfined spaces:  
a) An unconfined space is one whose volume is greater  
than 50 cubic feet per 1000 Btu per hour of the  
combined rating of all appliances installed in the space.  
That would be 5850 cubic feet for the AquaStar GWH  
1000 P alone.  
b) Installations in structures that have been tightly  
constructed (air infiltration rate of 0.40 ACH or less)  
must be provided for combustion air per the National  
Fuel Gas Code. Consult a HVAC specialist if your air  
infiltration rate is questionable.  
Appliances located in confined spaces:  
The confined space must be provided with two  
permanent openings, one commencing within 12  
inches of the top and one commencing within 12 inches  
of the bottom of the enclosure. Each opening must have  
a minimum free area of one square inch per:  
1000 Btu/hr if all air is taken from inside the building.  
2000 Btu/hr if all air is taken from the outside by  
horizontal ducts.  
4000 Btu/hr if all air is taken from the outside by  
direct openings or vertical ducts.  
Or the confined space must be provided with one  
permanent opening or duct that is within 12 inches of  
the ceiling of the enclosure. This opening must have a  
minimum free area of one square inch per:  
3000 Btu/hr if all air is taken from the outside by a  
direct opening or vertical duct.  
Louvers, grills and screens have a blocking effect. If the  
effective free area is not known, increase the sizes of  
your openings by 400% if your louvers are wood and by  
135% if your louvers are metal. Refer to the National  
8
6 720 608 124  
 
Installation instructions  
Keep the horizontal section short and avoid too many  
elbows. The maximum horizontal run allowed is half of  
the total vertical vent height; horizontal vent connectors  
and elbows are not to be considered in the total gas  
vent height.  
3.6 Venting  
Danger: Do not reduce the vent pipe  
size. Do not put an elbow directly on top  
of heater. Failure to follow venting  
requirements may cause dangerous  
exhaust gases to enter living space.  
Vent termination:  
The gas vent constructed of double wall Type B gas  
vent must terminate above the roof surface with a listed  
vent cap at a height that's in accordance with Fig. 10  
and table 2, provided it is at least 8 feet (2.4 m) from a  
vertical wall or similar obstruction. All other gas vents  
that are not able to terminate within the minimum  
specified height allowed must terminate not less than 2  
feet (0.6 m) above the highest point where it's passed  
through the roof and at least 2 feet (0.6 m) higher than  
any vertical wall or similar obstruction within 10 feet (3.1  
m).  
B Minimum vent pipe diameter: 4 inches  
B Minimum vertical vent height: 6 feet, with no elbows  
B Establish 12 inch rise before any elbow  
The heater must be vented to the outside following all  
local ordinances and specifications for installing a gas  
appliance vent or chimney. The heater must be located  
as close as practicable to a vertically rising chimney or  
vent that has a listed vent cap at its termination point.  
The venting system must be designed and constructed  
so as to develop a positive flow adequate to remove flue  
gasses to the outdoors. Consult the National Fuel Gas  
Code if the vent will have elbows or share venting with  
another natural draft appliance.  
LISTED VENT CAP  
Warning: Do not combination vent with  
a mechanically vented appliance.  
MINIMUM 6  
FEET (1.8M)  
3.6.1 Horizontal venting  
LISTED GAS VENT  
Warning: Horizontally venting to a  
vertically constructed vent stack along  
an outside wall of a building is not  
permissible.  
ESTABLISH A ONE  
FOOT RISE BEFORE  
ANY ELBOWS  
Warning: Horizontally venting to a  
sidewall vent terminator is not  
permissible.  
Fig. 9 Flat roof  
3.6.2 Vertical venting  
B A 4 inch diameter gas vent constructed of double  
wall Type B gas vent is recommended. Under no  
circumstances should the vent pipe be reduced in  
size.  
B An approved gas vent connector must be attached to  
the top of the water heater and rise vertically at least  
12" before entering into an approved gas vent  
connector elbow.  
B The minimum vertical gas vent height allowed is 6  
feet; horizontal vent connectors and elbows are not  
to be considered in the total gas vent height.  
B All gas vent sections must be secured to each other  
with sheet metal screws and be properly supported.  
Horizontal runs:  
Any gas vent section that is greater than 45 degrees  
from the vertical is considered horizontal. Horizontal  
sections must slope upwards at least ¼ inch for every  
foot of its horizontal length and be properly supported.  
9
6 720 608 124  
 
Installation instructions  
Masonry chimney  
GAS VENT TERMINATIONS FOR LISTED VENT CAPS  
Masonry chimneys shall be built and installed in  
accordance with NFPS 211 or local codes. A minimum  
4" diameter gas vent pipe (metal double wall Type B),  
or an approved clay flue liner or a listed chimney lining  
system must be used when venting into a naturally  
drafting, internal masonry chimney. Local codes may  
require the use of both gas vent and an approved lining  
system when venting into a masonry chimney. The  
Commonwealth of Massachusetts requires the use of a  
listed liner. Lining systems include approved clay flue  
lining, a listed chimney lining system or other approved  
material that will resist corrosion, erosion, softening, or  
cracking from exhaust flue gases at temperatures up to  
1800 degrees F. The lining system must be listed for  
use with naturally drafting, draft hood equipped gas  
appliances. Follow local codes and refer to NFGC 54  
and NFPA 58.  
Roof pitch  
H (minimum) feet  
meters  
0.30  
0.38  
0.46  
0.61  
0.76  
0.99  
1.22  
1.52  
1.83  
2.13  
2.27  
2.44  
Flat to 6/12  
1.0  
1.25  
1.5  
2.0  
2.5  
3.25  
4.0  
5.0  
6.0  
7.0  
7.5  
8.0  
6/12 to 7/12  
Over 7/12 to 8/12  
Over 8/12 to 9/12  
Over 9/12 to 10/12  
Over 10/12 to 11/12  
Over 11/12 to 12/12  
Over 12/12 to 14/12  
Over 14/12 to 16/12  
Over 16/12 to 18/12  
Over 18/12 to 20/12  
Over 20/12 to 21/12  
Table 2  
Existing interior masonry chimney  
The metal gas vent pipe should be permanently  
mounted inside the masonry chimney. Double wall Type  
B gas vent is recommended. The masonry chimney may  
have to be tile or metal lined before the insertion of the  
gas vent pipe; check local codes for clarification. The  
lining material must be listed for use only with naturally  
drafting, draft hood equipped gas appliances. Follow  
manufactures instructions for installation of listed lining  
material. You may not vent any other fuel burning  
appliances into any free space remaining in the  
chimney. The minimum vertical gas vent length within  
the masonry chimney should be no less than 6 ft (1.8  
m); the vent terminator should extend at least 3 feet (0.9  
m) above where the chimney meets the roofline and at  
least 2 feet (0.6 m) higher than any vertical wall or  
similar obstruction within 10 feet (3.1 m). The top of the  
gas vent should have an approved vent terminator. See  
Fig. 11.  
LISTED  
VENT CAP  
GAS  
VENT  
VENT  
CONNECTOR  
Establish a  
one foot  
rise before  
any elbows  
Fig. 11 Masonry chimney  
LOWEST DISCHARGE  
LISTED VENT CAP  
OPENING  
H (minimum) height  
from roof to lowest  
discharge opening  
X
12  
ROOF  
PITCH IS  
X/12  
MINIMUM 6  
FEET (1.8M)  
LISTED GAS VENT  
ESTABLISH A ONE  
FOOT RISE BEFORE  
ANY ELBOWS  
Fig. 10 Pitch roof  
10  
6 720 608 124  
 
Installation instructions  
B Attach the appliance regulator to the inlet gas pipe.  
3.7 Gas piping & connections  
B The minimum diameter required for any appliance  
Before connecting the gas supply, check the rating  
plate on the right side of the heater to be sure that the  
heater is rated for the same gas to which it will be  
connected.  
In the United States: The installation must conform with  
local codes or, in the absence of local codes, the  
National Fuel Gas Code ANSI Z223.1/NFPA 54.  
In Canada: The Installation should conform to CGA  
B149 INSTALLATION CODES and/or local installation  
codes.  
connector used is ½”.  
B National Fuel Gas Code requires that a sediment  
trap (drip leg) be installed on gas appliances not so  
equipped. The drip leg must be accessible and not  
subject to freezing conditions. Install in accordance  
with the recommendations of the serving gas  
supplier.  
When connections are made, check for gas leaks at all  
joints. Apply some gas leak detection solution to all gas  
fittings. Bubbles are a sign of a leak. A combustible gas  
detector may also be used to detect for leaks.  
Mount regulator to gas inlet pipe as shown in Fig. 12.  
The arrow on the back of the regulator indicates the  
direction of gas flow and should point toward the  
appliance.  
Danger: If you have a leak, shut off the  
gas. Tighten appropriate fittings to stop  
leak. Turn the gas on and check again  
with a gas leak detection solution.  
Never test for gas leaks using a match  
or flame.  
HIGH ALTITUDE INSTALLATION  
The pressure regulator provided with the heater is  
adjusted to deliver the proper gas pressure (as  
indicated on the rating plate and in the manual for  
altitude up to 2000 feet (660 meters) above sea level.  
On appliances being installed above 2000 ft (660  
meters) elevation, the inlet gas pressure should be set  
at installation to the value shown below.  
Note: The gas pressures specified below refer to  
pressures taken at the pressure tap on the gas inlet pipe  
just above the regulator. See chapter 3.8 for measuring  
gas pressure.  
Fig. 12 Installation of Gas Pressure Regulator  
Note: The GWH 1000 P comes with a gas pressure  
regulator. Failure to install or altering the gas pressure  
regulator will be a violation of CSA certification of the  
unit. The regulator supplied with the heater is preset for  
the gas shown on the rating plate to the correct  
pressure. It is an appliance level regulator designed for  
(low inlet) pressure (less than 1/2 Psig or 14" W.C.).  
MAXIMUM INLET GAS FLOW PRESSURE SETTING  
Nat. Gas  
inches W.C.  
Liquid Propane  
inches W.C.  
Altitude  
0’ - 2 000 ft  
5.7”  
4.6”  
10.5”  
8.4”  
Warning: DO NOT connect to an  
unregulated or high pressure propane  
line or to a high pressure commercial  
natural gas line.  
2 000 ft - 4 500 ft  
Table 3 Above 4.500 ft consult your local gas provider  
GAS LINE SIZING  
The gas supply piping should be sized according to the  
applicable code for a maximum draw of 74,900 BTUH.  
Measure the length of gas supply line and use the tables  
in Fig. 13 or the gas line manufacturer’s sizing tables to  
determine the pipe diameter necessary to  
accommodate the BTU demand of the unit. If there are  
more gas appliances drawing on the same line, size the  
gas line according to the total maximum amount of BTU  
draw for all appliances.  
Warning: The heater must be isolated  
from the gas supply piping system  
during any pressure testing of that  
system at test pressures equal to or  
more than 0.5 psig. If overpressure has  
occurred, such as through improper  
testing of the gas lines or malfunction of  
the supply system, the gas valve must  
be checked for safe operation.  
Note: Under sizing the gas line may result in diminished  
output and improper operation. See chapter 3.8 for the  
procedure to confirm gas pressure.  
GAS CONNECTIONS  
B Install a manual gas shut off valve, on the gas supply  
line.  
B Install a union when connecting gas supply.  
11  
6 720 608 124  
 
Installation instructions  
FOR NATURAL GAS  
Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop  
of 0.3 in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands.  
Copper tubing is prohibited for use with Natural Gas in the Commonwealth of Massachusetts and not recommended  
elsewhere.  
Follow boxed numbers for piping just one GWH 1000 P (example: ¾” B.I. Natural Gas pipe for 20 ft (6.1m). will  
handle 190,000 btu’s (55.7 kWh). For multiple appliances combine the total btu input load and then refer to  
applicable chart below.  
Nominal  
Iron  
Pipe  
Size  
Length of Black Iron Pipe, Feet  
Internal  
Diameter  
inches inches  
10  
20  
30  
40  
50  
60  
70  
80  
90  
90 100 125 150 175 200  
84 79 72 64 59 55  
3/4  
1
0.824  
1.049  
278 190 152 130 115 105 96  
520 350 285 245 215 195 180 170 160 150 130 120 110 100  
1 1/4  
1.380 1050 730 590 500 440 400 370 350 320 305 275 250 225 210  
Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet  
Tube  
size,  
inches  
EHD*  
10 20  
30  
47  
96  
40  
41  
50  
37  
60  
34  
1/2  
18 EHD 82 58  
23 EHD 161 116  
3/4  
1
83  
75  
68  
30 EHD 330 231 188  
162  
325  
144  
292  
131  
267  
* EHD = Equivalent Hydraulic Diameter. The greater the  
value of EHD, the greater the gas capacity of the tubing  
1 1/4 37 EHD 639 456 374  
.
FOR LP GAS  
Maximum Capacity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column Inlet  
Pressure) (Based on a Pressure Drop of 0.5 Inch Water Column).  
* EHD = Equivalent Hydraulic Diameter. The greater the  
value of EHD, the greater the gas capacity of the tubing.  
N ominal  
Length of Flexible Corrugated Stainless Steel Tubing (CSST), Feet  
Iro n pipe  
size  
Black Iron Pipe  
Lenght of pipe, Feet  
Tube  
size  
inches  
EHD*  
inches  
10 20 30 40 50 60 80 100 125 150 200  
10 20  
30  
74  
40  
50 60  
1/2  
3/4  
291 200 160 137 122 110 94 84  
74  
67  
58  
1/2  
3/4  
1
18 EHD 129 91  
64  
58 53  
118 107  
227 207  
608 418 336 287 255 231 197 175 155 140 120  
1145 787 632 541 480 434 372 330 292 265 227  
23 EHD 254 183 151  
30 EHD 521 365 297  
131  
256  
1
1 1/4 37 EHD 971 661 528  
449  
397 359  
Maximum Capacity of Semi-Rigid copper Tubing in  
Thousands of BTU per Hour of Undiluted Liquefied  
Petroleum Gases (at 11 inches Water Column Inlet  
Pressure).  
Copper (LP gas only)  
Length of Tubing, Feet  
Outside  
diameter  
Inch  
10 20 30  
39 26 21  
92 62 50  
40  
19  
41  
50 60 70 80 90 100  
3/8  
1/2  
_
_
_
_
_
_
(Based on a Pressure Drop of 0.5 Inch Water Column)  
37 35 31 29 27 26  
79 72 67 62 59 55  
* Source National Fuel Gas Code NFPA 54, ANSI Z223.1  
- No Additional Allowance is necessary for an ordinary  
number of fittings  
5/8 199 131 107 90  
3/4 329 216 181 145 131 121 112 104 95 90  
Fig. 13  
12  
6 720 608 124  
 
Installation instructions  
Although water piping throughout your structure may be  
other than copper, we recommend that copper piping  
or suitably rated stainless steel flex line piping be used  
for at least three feet before and after the heater (follow  
local codes if more stringent). Never sweat any rigid  
piping directly to or beneath the water connections or  
damage can occur to the internal water valve from  
heating of the pipe. Plastics or other PEX type plumbing  
line materials are not recommended for connecting  
directly to the water heater. Keep water inlet and outlet  
pipes to no less than ½" (12.7mm) diameter to allow the  
full flow capacity.  
3.8 Measuring gas pressure  
Connecting manometer  
B Shut off gas.  
B Remove front cover and locate inlet gas pressure  
measuring point on the right side, see Fig. 14.  
B Loosen screw from test point on the right side and  
connect manometer tube on test point.  
It is recommended that all water piping below the heater  
be properly insulated to avoid heat loss.  
If the cold and hot connections to the heater are  
reversed, the heater will not function. Be certain there  
are no loose particles or dirt in the piping. Blow out or  
flush the lines before connecting to the water heater.  
Full port valves should be installed on both the cold  
water supply and hot water outlet lines to facilitate  
servicing the heater (see Fig. 15). For installation on a  
private well system with the use of a pressure tank, the  
lowest pressure range setting recommended is 30-50  
psi (2.07 and 3.45bar).  
Connecting the pressure relief valve (PRV)  
The pressure relief valve supplied with the heater must  
be installed at the time of installation. No valve is to be  
placed between the PRV and the heater. No reducing  
coupling or other restriction may be installed in the  
discharge line. The discharge line must be a minimum of  
4” above a drain and installed such that it allows  
complete drainage of both the PRV and the line.  
The location of the PRV must be readily accessible for  
servicing or replacement, and be mounted as close to  
the water heater as possible. See Fig. 15. To install the  
PRV, a suitable fitting connected to an extension on a  
“T” fitting can be sweated to the hot water line.  
Support all piping.  
Fig. 14 Gas pressure measuring point  
A
Inlet tap  
Static pressure test  
B Turn gas supply back on.  
B Record static gas pressure reading on back page of  
manual.  
Operating pressure test  
B Turn on all hot water taps served by the water heater.  
B Set flow control knob fully clockwise.  
B Set slide control to the right.  
B Operate all other gas appliances on same gas piping  
system at maximum output.  
B Record operating gas pressure reading on back  
page of manual.  
Gas pressures lower than 5.7" W.C. for Natural Gas or  
10.5" W.C. for LP Gas will result in insufficient degree  
rise to the hot water being used, and must be corrected.  
See Gas Line Sizing under chapter 3.7.  
3.9 Water connections  
When facing the heater, the ½” cold water inlet is on the  
bottom right and the hot water outlet is on the bottom  
left.  
B Install unions or the Webstone service valves  
when connecting plumbing to the water  
heater. This will facilitate any necessary  
cleaning and servicing.  
13  
6 720 608 124  
 
Operation instructions  
4
Operation instructions  
4.1 For your safety read before  
operating your water heater  
Warning: If you do not follow these  
instructions exactly, a fire or explosion  
may result causing property damage,  
personal injury or loss of life.  
Note: Upon initial installation,  
existence of air in the gas supply  
i
line and in the water line may  
cause some ignition delay. In that  
case, repeat the ignition process  
until all the air has been purged.  
Fig. 15 Plumbing connections and pressure relief  
valve shown with optional Webstone service  
valves  
A. This appliance employs a piezo-igniter to light the  
pilot burner. When lighting the pilot, follow these  
instructions exactly.  
B. What to do if you smell gas.  
3.10 Recirculation application  
WHAT TO DO IF YOU SMELL GAS  
Since recirculation through the heater is not  
permissible, the following drawing is provided to outline  
a proper recirculation application using the Aquastar  
water heater with an Ariston minitank. This schematic is  
for illustration only and must not be used for actual  
installation without appropriate engineering and  
technical advice from a professional properly licensed in  
locality where the installation is made.  
B Close gas valve. Open windows  
B Do not try to light any appliance.  
B Do not touch any electric switch; do not use any  
phone in your building.  
B Immediately call your gas supplier from a neighbors  
phone. Follow the gas supplier’s instructions.  
B If you cannot reach your gas supplier, call the fire  
department.  
C. Use only your hand to push in the gas control  
buttons. Never use tools. If a button will not push in,  
check to make sure the buttons are being pushed in the  
proper sequence. Follow these instructions exactly. If  
control button(s) are jammed, close the heater’s  
individual manual shutoff valve and call a qualified  
service technician. Forced or attempted repair may  
result in a fire or explosion.  
D. Do not use this appliance if any part has been under  
water. Immediately call a qualified service technician to  
inspect the appliance and to replace any part of the  
control system and any gas control which has been  
under water.  
Fig. 16 Recirculation application  
The use of a small electric mini-tank (4-6 gallon size)  
should be used for this application and designed so the  
pump will circulate the water through the mini-tank and  
the building's hot water return loop only. A timed or  
thermostatically controlled operation of the pump is  
commonly done. The GWH 1000 P should be plumbed  
in line before the mini-tank water heater. Contact Bosch  
Water Heating if further instruction is needed.  
14  
6 720 608 124  
 
Operation instructions  
B With the gas valve button fully depressed, light pilot  
by pushing the piezo button. This step may have to  
be repeated.  
4.2 Lighting instructions  
B STOP! Read the previous safety information.  
B The gas valve must be turned off by sliding the gas  
valve button to all the way to the left.  
Fig. 17  
Fig. 20  
B Wait five (5) minutes to clear out any gas. If you smell  
gas, STOP! Follow “B” in the safety information  
above on this plate. If you don’t smell gas, go to next  
step.  
B Observe the pilot flame through the peephole. The  
gas valve button should be held down for at least 15  
seconds with pilot burning before releasing. When  
the gas valve button is released, the pilot should  
continue to burn.  
B The pilot burner window is located in the front center  
of the cover.  
- If the gas valve button does not pop out when  
released, stop and immediately call your service  
technician or gas supplier.  
B Slide the gas valve button to the position  
.
- If pilot does not stay lit, repeat all steps.  
- If pilot will not stay lit after several tries, slide the gas  
valve button all the way to the left and call service  
technician or gas supplier.  
B The heater will now fire at minimum power when  
water is drawn at a rate greater than the required  
activation flow rate.  
Note: If main burner should fail to ignite, make sure pilot  
is burning. If not, repeat lighting steps.  
Note: The GWH 1000 P operates in two modes. See  
SETTING THE WATER TEMPERATURE.  
Fig. 18  
B Fully depress gas valve button.  
4.3 To turn off appliance  
B Slide the gas valve button all the way to the left and  
turn off the installer supplied manual gas shutoff on  
the supply line to the heater.  
Fig. 19  
Fig. 21  
4.4 Setting the water temperature  
The GWH 1000 P has a gas control that modulates  
burner input in response to flow. Its purpose is to  
15  
6 720 608 124  
 
Operation instructions  
ensure that the hot water temperature will remain  
steady, although the water flow demand might vary. The  
output temperature can be adjusted with either the  
temperature adjustment knob or the gas control slide.  
Temperature adjustment knob  
The temperature adjustment knob on the front bottom of  
the heater (see Fig. 22) adjusts temperature by  
adjusting flow capacity. See table 4 for details.  
Fig. 24  
4.5 Draining water from heater  
If there is a risk of freezing, proceed as follows:  
B Remove the retaining clip from threaded bushing  
(pos. 1).  
B Remove threaded bushing (pos. 2) from water valve.  
B Empty the appliance of all water.  
Fig. 22  
Knob  
position  
Counter-  
clockwise  
Clockwise  
Degree rise  
90°F  
45°F  
Activation rate  
Max flow rate  
0.5 GPM  
2.0 GPM  
1.1 GPM  
3.7 GPM  
Table 4 Temperature rise (slide control to the right)  
As the temperature adjustment knob is turned counter-  
clockwise, the output temperature will lower and the  
activation rate will be raised. Turning the knob  
clockwise will raise the temperature and lower the  
activation rate.  
Fig. 25 Drain plug and filter location  
1
2
Retaining clip  
Threaded bushing  
Gas control slide button  
The gas control slide button adjusts temperature by  
adjusting how much gas is allowed to flow to the  
burners.  
As the slide is adjusted to the left, the output  
temperature will lower, with the lowest setting being the  
small flame position.  
Fig. 23  
The hottest position is the highest flame position all the  
way to the right.  
16  
6 720 608 124  
 
Maintenance and service  
5
Maintenance and service  
by removing the retaining clip on water valve assembly  
and pulling the pipe free from the water valve. Loosen  
the two set screws at the bottom of the water valve  
where it connects to the gas valve. If the set screws are  
seized, STOP and call Bosch tech support before  
proceeding. Forcing and snapping seized set screws  
may cause irrevocable damage to the water valve and  
gas valve assemblies. Remove the water valve by  
pulling it to the right. Separate the two halves of the  
water valve by removing the five screws on the left side  
of the water valve. Apply lithium or faucet & valve grease  
to the pushrod and o-ring. (See Fig. 25, num. 23).  
Inspect the venturi and clean if necessary. (see Fig 28,  
num. 23).  
5.1 Maintenance intervals  
Warning:  
Failure  
to  
perform  
recommended maintenance may result  
in complete failure of the unit over time.  
The warranty does not cover failures  
due to improper or insufficient  
maintenance.  
The GWH 1000 P requires periodic maintenance. The  
below time maintenance intervals should keep the unit  
operating for many years.  
Every year  
B Inspect inlet water filter screen ( 5.2)  
B Inspect pilot assembly and flame ( 5.3)  
B Inspect burner assembly ( 5.4)  
Rebuilding the water valve  
Several parts within the water valve should be replaced  
every 3 to 5 years depending on water quality and  
usage. The parts list and instructions can be found on  
rebuild the water valve can result in decreased  
performance or damage to the heater.  
Every 2 years  
B Lubricate and clean water valve ( 5.2)  
Every 3 to 5 years  
5.3 Pilot  
B Rebuild water valve ( 5.2)  
B Clean pilot assembly and clean or replace orifice  
Inspecting pilot  
( 5.3)  
The pilot should burn with a clean sharp blue flame. The  
flame should fully engulf the tip of the thermocouple. If  
it does not, clean the pilot assembly per procedure  
below.  
5.2 Water valve  
The water valve is the main control that tells the heater  
to fire. If the periodic maintenance is neglected, more  
costly damage may occur over time.  
Cleaning pilot assembly  
Shut off gas supply to the heater using installer supplied  
manual gas shutoff. Locate pilot gas tubing mounted in  
the center of the burner assembly. At the base of the  
pilot gas tubing there is a retaining clip. Release pilot  
gas tubing from this clip. Push upwards on other end of  
pilot gas tubing to release it from burner mount.  
Remove brass hex headed pilot orifice from gas valve  
(located near base of pilot gas tubing). Soak orifice and  
pilot gas tubing in carburetor cleaner for 30 minutes.  
Dry off and reinsert orifice in gas valve. If heater is an LP  
unit, replace orifice. Reinstall the pilot gas tubing  
following removal instructions in reverse. Open gas  
supply and return heater to service.  
Inspecting inlet water filter screen  
Shut off the installer supplied cold water isolation valve  
to the heater. If one is not installed, install before  
proceeding. Open the nearest hot water tap to drain the  
plumbing lines. Position a bucket under the heater's  
water valve assembly to catch any water that may drain  
from the heater. Remove the filter retaining pin located  
at base of water valve (see Fig. 25). Remove the  
threaded bushing to access the cylindrical filter inside.  
Remove filter, clean with water and inspect for damage.  
If the filter is at all damaged, it should be replaced.  
Lubricating the water valve  
Caution: Do not ream or poke orifice as  
it will enlarge orifice opening.  
A more detailed instruction is available on our website  
supplied cold water isolation valve to the heater. If one  
is not installed, install before proceeding. Open the  
nearest hot water tap to drain the plumbing lines.  
Position a bucket under the heater's water valve  
assembly to catch any water that may drain from the  
heater. Disconnect the inlet water pipe going to the  
back of the water valve. Disconnect the water pipe  
leading out of water valve to the heat exchanger. Do this  
17  
6 720 608 124  
 
Maintenance and service  
12. Run solution through the heat exchanger until the  
solution returning to the descaling reservoir comes out  
clear. (Changing to a fresh solution may be necessary  
during this process).  
5.4 Main burners  
The main burner flames should be blue, with a more  
intense blue cone in the center core. Yellow flames  
could be a sign of wrong size gas orifices or dirty  
burners, a blockage on the heat exchangers fins. If  
some burners have yellow flames while others have blue  
flames, it is likely that dust, lint or spider webs have  
partially clogged the burner venturis. To clean the  
burners, contact a gas service person.  
13. Disconnect all lines and drain all solution from heat  
exchanger. Properly discard of solution  
14. Position a container below the hot water outlet and  
connect cold water supply. Open cold water supply  
isolation valve and flush heat exchanger with clean  
water.  
15. Shut cold water isolation valve and reconnect hot  
water supply to the water heater.  
5.5 Vent assembly  
Inspect the draft hood and heat exchanger fins for signs  
of soot build-up or any other foreign material such as  
spider webs. Clean out any debris found in the vent  
hood. Signs of soot indicate insufficient combustion air  
or exhaust draft. Check for vent assembly blockage or  
combustion air blockage on the underside of the unit.  
16. Reconnect electrical supply to unit, open water  
isolation valves, and return the unit to service.  
5.6 Mineral scale build-up  
The GWH 1000 P, when operated at lower  
temperatures settings, does not accumulate mineral  
build-up. If however, the heater is used at the higher  
temperature settings and the water has a high mineral  
content, periodic descaling may be necessary. The  
heating coils should be flushed with a descaling  
solution.  
5.6.1 Descaling heat exchanger  
1. Disconnect electrical supply from the water heater.  
2. Shut off the water supply to the water heater using  
(installer supplied) isolation valve.  
3. Open hot water taps to drain and relieve pressure  
from the plumbing system  
Fig. 26  
4. Drain water from the unit's heat exchanger by  
disconnecting inlet and outlet water connections  
5. Connect the line (A) from the outlet of the circulating  
pump (installer supplied) to the inlet water fitting on the  
water heater  
6. Using another line (B), connect to the water outlet  
fitting on the water heater. Route the other end of this  
line into a descaling reservoir  
7. Using a 3rd line (C) from the descaling reservoir,  
connect to the inlet side of circulating pump. Verify  
there is a filter on the end of the line in the descaling  
reservoir.  
8. Make sure all connections are "hand tight."  
9. Fill tank with descaling solution so lines inside are  
submersed. We recommend a straight white vinegar  
solution. If using a commercial descalant, refer to  
manufacturer's instructions on dilution with water.  
10. Operate the circulating pump.  
11. Make sure there are no leaks and the solution is  
flowing from the descaling reservoir through the heat  
exchanger and returning to the reservoir.  
18  
6 720 608 124  
 
Troubleshooting  
6
Troubleshooting  
4. Pilot flame should be blue in color and completely  
engulfing the tip of the thermocouple. If not, have a  
licensed gas technician verify gas pressure is in  
accordance with manufacturer's specifications  
(chapter 3.9) and clean or replace the pilot orifice  
(chapter 5.3).  
6.1 Introduction  
Many of the questions customers ask regarding  
operation of this unit can be answered by following the  
troubleshooting steps as outlined below. Visit our web  
troubleshooting. For best results, perform each step  
before proceeding to the next. The suggested solutions  
may require that the cover be taken off. (See chapter  
3.4).  
5. Have a licensed gas technician verify the proper  
operation of the thermocouple by measuring the  
millivoltage from the thermocouple lead to ground. The  
proper reading should be 24mVDC or greater. If the  
reading is lower, the thermocouple may be defective.  
Call Bosch Water Heating for further instructions.  
6.2 Pilot does not light  
1. Verify gas supply is on at Natural Gas meter or  
Propane Tank. Make sure all manual gas shut off valves  
are in the open position. Have licensed gas technician  
confirm adequate gas pressure at the inlet tap  
(chapter 3.9). If gas is not present, verify manufacturer  
supplied Maxitrol regulator is in the upright position. The  
arrow on the back of the regulator should point in the  
same direction as gas flow.  
6.4 Pilot goes out during or after hot  
water use  
1. Pilot outage during use typically results from the  
unit's safety overheat/high limit sensors interrupting the  
pilot circuit. The GWH 1000 P does not have a  
thermostat. If inlet water is preheated, the unit will  
overheat, stopping the flow of gas. Plumb inlet with a  
cold water line only.  
2. If the unit was just installed or the gas lines have been  
worked on, there may be air in the gas line. Centered in  
the sparking position, hold down the gas control slide  
button while hitting the pilot igniter button every few  
seconds. It may take several minutes to bleed air out of  
the gas line.  
2. Failure to vent properly by reducing pipe diameter,  
improper use of elbows or not meeting required vent  
length are common causes that deactivate the pilot  
safety circuit. Confirm venting is in accordance with  
manufacturer's specifications (see chapter 3.7).  
3. Verify a spark is being thrown at pilot area while gas  
control slide button, centered in the single flame  
position, is being firmly depressed. Repeatedly push in  
pilot igniter button to light the pilot. If no spark is  
present, verify proper wire connection to the electrode.  
3. Confirm the combustion air requirements are being  
met in accordance with manufacturer's specifications  
(see chapter 3.6). Proper venting and combustion air  
will ensure a proper draft.  
4. Confirm that the burners in the water heater go off  
immediately when the hot water is turned off. If they  
remain on or shut down slowly, then the overheat  
sensor (ECO) will interrupt the pilot circuit and shut off  
all gas to the heater. The water valve assembly, which  
actuates the burners, may be dirty and require periodic  
maintenance (every 2 - 5 years depending on water  
quality and use) (see chapter 5.2).  
4. Pilot assembly may be blocked. Clean or replace the  
pilot orifice (chapter 5.3).  
6.3 Pilot lights, but goes out when  
button is released  
1. When lighting pilot ensure the gas control slide  
button is fully depressed and held down for at least 20  
seconds after pilot is lit.  
5. Check all connections of the pilot safety circuit. The  
pilot safety circuit consists of a thermocouple, overheat  
sensor (ECO), flue gas sensor and the electromagnet  
(See parts diagram for locations). Clean sensor  
connections with light sandpaper if corrosion is evident.  
The electromagnet connection is 5mm nut from the  
thermocouple which screws into a larger 17mm nut.  
Tighten both nuts snugly but do not over tighten.  
2. Verify gas type indicated in rating sticker located on  
right hand side of cover, coincides with the gas type you  
are using. NG is a natural gas unit and LP is for liquid  
propane.  
3. Check all connections of the pilot safety circuit. The  
pilot safety circuit consists of a thermocouple, overheat  
sensor (ECO), flue gas sensor, safety spillage  
switch(models with Powervents only) and the  
electromagnet (See parts diagram for locations). Clean  
sensor connections with light sandpaper if corrosion is  
evident. The electromagnet connection is 5mm nut from  
the thermocouple which screws into a larger 17mm nut.  
Tighten both nuts snugly but do not over tighten.  
6. Verify pilot flame completely engulfs the  
thermocouple tip. If pilot is too small, clean pilot orifice  
(see chapter 5.3).  
7. If the water has a high mineral content, the heat  
exchanger may be scaled internally. This restricts the  
water path, causing the water to over heat which shuts  
all gas off to the heater. Instructions for descaling the  
19  
6 720 608 124  
 
Troubleshooting  
heat  
exchanger  
are  
available  
at  
point, which shuts off the burners. The end result is  
nothing but cold water coming out of the outlet.  
Reduce the need for cold water mix by setting the gas  
slide control button towards the single flame position  
for lower hot water temperatures. If the problem  
detailed service bulletin on this problem.  
8. If steps 1 through 7 do not correct the problem, then  
confirm that the gas pressure is adequate. Ensure gas  
pressure is in accordance with manufacturer's  
specifications (see Chapter 3.9). A gas pressure  
reading is needed to proceed further. Contact your  
original installer or a licensed gas technician to obtain  
this reading.  
4. The GWH 1000 P is designed to modulate gas flow  
to the burners when water flow varies. If the water  
pressure in the home is erratic and the water flow is not  
consistent while a tap is opened, then the temperature  
of hot water will fluctuate. The minimum water pressure  
for the home should be 30psi or greater. For installation  
on a private well system with the use of a pressure tank,  
the lowest pressure range setting recommended is 30-  
50 psi (2.07-3.45 bar). The use of a pressure reducing/  
regulating valve before the water heater (directly after  
pressure tank on well systems) is an effective way to  
maintain constant water pressure to the water heater.  
Watts brand 25AUB- ¾" or N35B-¾" pressure  
reducing/regulating valves or equivalent are suggested.  
6.5 Burners do not light with water  
flow  
1. Verify the pilot is lit.  
2. Verify the gas control slide button is between the  
1flame and 3 flame positions.  
3. Verify the cold water supply is connected to the right  
side of the heater.  
4. Close installer supplied cold water shut off valve (if  
none installed, install before proceeding). Open all hot  
water taps supplied by the heater. Wait 5 minutes and  
check all taps. Any water running is a sign of a plumbing  
crossover. Consult a local plumber or service person for  
help in correcting a plumbing crossover.  
5. If the inlet water temperature is not steady then the  
hot water temperature from the water heater will  
fluctuate. The GWH 1000 P modulates its burners  
when the flow rate is changed; it does not have a  
thermostat and will not adjust to changes in inlet water  
temperature.  
5. Verify flow through the water heater is sufficient. Turn  
temperature adjustment knob all the way clockwise.  
Fully open a hot water faucet and fill a quart container.  
If the container fills in 30 seconds or less, the flow rate  
(1/2 gallon per minute) is sufficient to activate the  
heater.  
6. If the inlet water temperature to the water heater is  
above 70°F, the heater may produce outlet  
temperatures that are too hot for most users. A  
temperature balance shower valve can automatically  
mix in cold water to reduce such hot water temperature.  
This can slow the flow within the tankless water heater,  
decreasing it below activation point, which shuts off the  
burners. In the event of any temperature instability with  
the use of a temperature balance shower valve, refer to  
shower valve manufacturer's instructions for internal  
adjustment setting. An adjustment should be made to  
minimize the amount of cold water the valve is adding.  
6. Inspect the water path outside of the heater for  
obstructions. Make sure all outlets (i.e. showerheads,  
faucet aerators and whole house filters) are clear of  
debris. Also, the water heater's inlet filter screen should  
be inspected and cleaned (see chapter 5.2).  
7. The water valve assembly, which actuates the  
burners, requires periodic maintenance (every 2 - 5  
years depending on water quality and use) (see  
chapter 5.2).  
7. The gas pressure also needs to be stable and  
adequate. Ensure gas pressure is in accordance with  
manufacturer's specifications (see chapter 3.9). A gas  
pressure reading is needed to proceed further. Contact  
your original installer or a local certified gas technician  
to obtain this reading.  
6.6 Hot water temperature fluctuates  
at tap  
1. Close off installer supplied cold water shut off valve  
(if none installed, install before proceeding). Open all  
hot water taps supplied by the heater. Wait 5 minutes  
and check all taps. Water running is a sign of a  
plumbing cross-over. Consult a local plumber or service  
person for help in correcting a plumbing crossover.  
8. A water valve, which has not been serviced, may be  
struggling to keep the gas valve open. The water valve  
requires periodic maintenance (every 2-5 yrs  
depending on water quality and use) (see chapter 5.2).  
2. Check for a clogged inlet water filter screen (see  
chapter 5.2).  
6.7 Water is too hot  
1. Verify gas type indicated in rating sticker located on  
right-hand side of cover, coincides with the gas type  
you are using. NG is a natural gas unit and LP is for  
liquid propane.  
3. Hot water is very hot out of the tap, requiring a lot of  
cold water to be added with it in order to attain a  
useable hot water temperature. The addition of too  
much cold will overpower and slow the flow within the  
tankless water heater, decreasing it below activation  
20  
6 720 608 124  
 
Troubleshooting  
2. Adjust the gas control slide button from three flame  
position towards the one flame position for cooler  
temperatures. If the water is still too hot, the  
temperature adjustment knob on the water heater  
maybe set too high. Lower the setting and test water  
temperature. This dial turns counter clockwise for lower  
temperatures and clockwise for higher temperatures.  
serviced (every 2-5 yrs depending on water quality and  
use) (see chapter 5.2).  
7. Gas pressure is too low. Ensure gas pressure is in  
accordance with manufacturer's specifications (see  
chapter 3.9). A gas pressure reading is needed to  
proceed further. Contact your original installer or a local  
certified gas technician to obtain this reading.  
3. Inlet water is preheated. This model does not have a  
thermostat and thus will not modulate flame height in  
order to prevent over heating. It is designed for a cold  
water feed only. Replumb the heater with cold water to  
the inlet.  
6.9 Burners ignite without hot water  
flow  
1. The water valve may be dirty and sticking, prohibiting  
it from fully closing the gas valve. This part needs to be  
periodically serviced (every 2-5 yrs depending on water  
quality and use) (see chapter 5.2).  
4. Increase the flow rate. Restrictions in the water path  
can slow the flow of water through the heater, resulting  
in very hot outlet temperatures. Restrictive  
showerheads and faucet aerators should be cleaned  
out or upgraded with less restrictive ones. In addition,  
the water heater's inlet filter should be cleaned and  
inspected (see chapter 5.2).  
6.10 Low hot water pressure  
1. Confirm adequate flow rate through the unit. With  
cold supply shut off to the unit, disconnect hot outlet  
side to the unit. Place a half gallon jug under hot outlet  
to catch water. Open cold supply and measure flow rate  
out of the unit. With temperature adjustment knob set all  
the way clockwise, the flow rate should be close to  
2gpm, filling the jug in 15 seconds. With the  
temperature adjustment knob set all the way  
counterclockwise, the flow rate should be close to  
4gpm, filling the jug in 7 seconds. If the flow rate is not  
adequate, inspect and clean the inlet filter screen (see  
chapter 5.2).  
5. If water is still too hot, consult service bulletins on  
further.  
6. If the water has a high mineral content, the heat  
exchanger may be scaled internally. This restricts the  
water path, causing the water to boil and produce  
extremely hot temperatures. Instructions for descaling  
the  
heat  
exchanger  
are  
available  
at  
6.8 Water is not hot enough  
2. Confirm the incoming water pressure to the unit is  
above the required 30psi.  
1. Verify gas type indicated in rating sticker located on  
right-hand side of cover, coincides with the gas type  
you are using. NG is a natural gas unit and LP is for  
liquid propane.  
3. Inspect the water path outside of the heater for  
obstructions. Make sure all outlets (i.e. showerheads,  
faucet aerators and whole house filters) are clear of  
debris.  
2. Flow at one particular tap is too great or too many  
fixtures are running at one time. Lower flow to stay  
within heater's specifications.  
4. Be sure to run only one major application at a time  
with this unit. Opening too many taps at one time can  
disperse water flow resulting in a diminished flow/  
pressure at all outlets.  
3. Ensure the gas control slide button is all the way to  
the 3 flame position. In addition, the temperature  
adjustment knob on water heater maybe set too low.  
Turn the knob clockwise for higher temperatures and  
test the water temperature.  
5. If the water has a high mineral content, the heat  
exchanger may be scaled internally. This restricts the  
water path, causing diminished water flow. Instructions  
for descaling the heat exchanger are available at  
4. Shut off installer supplied cold water shut off valve (if  
none installed, install before proceeding). Open all hot  
water taps supplied by the heater. Wait 5 minutes and  
check all taps. Any water running is a sign of a plumbing  
crossover. Consult a local plumber or service person for  
help in correcting a plumbing crossover.  
5. Inspect the water path outside of the heater for  
obstructions. Make sure all outlets (i.e. showerheads,  
faucet aerators and whole house filters) are clear of  
debris. Also, the water heater's inlet filter screen should  
be inspected and cleaned (see chapter 5.2).  
6. The water valve may be dirty, prohibiting it from fully  
opening the gas valve. This part needs to be periodically  
21  
6 720 608 124  
 
Troubleshooting  
can be accessed and brushed or vacuumed clean.  
Instructions to remove burners are available at  
6.11 Noise when heater is running  
1. Confirm adequate flow rate through the unit. With  
cold supply shut off to the unit, disconnect hot outlet  
side to the unit. Place a half gallon jug under hot outlet  
to catch water. Open cold supply and measure flow rate  
out of the unit. With temperature adjustment knob set all  
the way clockwise, the flow rate should be close to  
2gpm, filling the jug in 15 seconds. With the  
temperature adjustment knob set all the way  
counterclockwise, the flow rate should be close to  
4gpm, filling the jug in 7 seconds. If the flow rate is not  
adequate, inspect and clean the inlet filter screen (see  
chapter 5.2).  
2. Inspect the water path outside of the heater for  
obstructions. Make sure all outlets (i.e. showerheads,  
faucet aerators and whole house filters are clear of  
debris. Restrictions in the water path can slow water  
flow through the heat exchanger causing it to boil and  
make noise.  
3. If the water has a high mineral content, the heat  
exchanger may be scaled internally. This restricts the  
water path, causing the water to boil resulting in noise  
and overheating. Instructions for descaling the heat  
6.12 Burners do not operate cleanly;  
yellow flames when operating  
1. Verify gas type indicated in rating sticker located on  
right-hand side of cover, coincides with the gas type  
you are using. NG is a natural gas unit and LP is for  
liquid propane.  
2. Gas pressure may be inadequate resulting in  
improper combustion. Ensure gas pressure is in  
accordance with manufacturer's specifications (see  
chapter 3.6). A gas pressure reading is needed to  
proceed further. Contact your original installer or a  
licensed gas technician to obtain this reading.  
3. For proper combustion at high elevations the inlet  
gas pressure should be set at installation to the value  
shown in table 3 on page 11 (while operating at  
maximum BTU). A gas pressure reading is needed to  
proceed further. Contact your original installer or a  
licensed gas technician to obtain this reading.  
4. Ventilation is not adequate. Ensure adequate  
combustion air is being supplied to the unit in  
accordance with manufacturer's specifications (see  
chapter 3.6).  
5. Make sure the water heater is vented properly. Check  
for proper draft and ensure venting is in accordance  
with manufacturer's specifications (see chapter 3.7).  
6. The water heater has burners much like a furnace. It  
is essential that they remain clean and are supplied with  
adequate air for combustion. If the flames burn yellow or  
orange, it is strongly recommended that the burners be  
removed from the unit and cleaned. Once the burners  
are removed, the fins in the top of the heat exchanger  
22  
6 720 608 124  
 
Protecting the environment  
7
Protecting the environment  
Packing  
The packing box may be fully recycled as confirmed by  
the recycling symbol  
.
Components  
Many parts in the heater can be fully recycled in the end  
of the product life. Contact your city authorities for  
information about the disposal of recyclable products.  
Saving water resources:  
B Make sure you close all the taps after any use. Avoid  
leaving the taps dripping. Repair any leaking tap.  
B Set the water heat to the temperature you want. This  
way you have the precise water temperature needed  
(mixing cold water to regulate temperature will  
increase the water temperature with consequent  
waste of water).  
For increased safety shut off the appliance from  
the main water supply if your are staying away  
from home for a considerable time.  
At below freezing temperatures, disconnect the  
plumbing connections to the heater and allow  
the heater to drain.  
To prevent any freeze damage, introduce short  
bursts of compressed air (20-40 psi) through  
these connections to remove the residual water  
in the horizontal pipes and water valve.  
Follow instructions in chapter 4.5 to remove any  
additional water remaining in the watervalve and  
heat exchanger.  
23  
6 720 608 124  
 
Interior components and diagram parts list  
8
Interior components and diagram parts list  
8.1 Interior components  
Fig. 27 Functional scheme  
4
5
10  
11  
20  
Heat exchanger  
Burner  
Temperature adjustment selector  
Water valve  
22  
26  
30  
102  
Flexible hot outlet  
Gas control slide  
Pilot gas tubing  
Piezo  
Gas connection  
24  
6 720 608 124  
 
Interior components and diagram parts list  
8.2 Components diagram  
5
4
6
44  
8
41  
39  
48  
50  
47  
12  
14  
19  
13  
18  
15  
9
10  
43  
11  
16  
20  
24  
51  
21  
23  
27  
52  
22  
38  
28  
30  
17  
25  
35  
31  
26  
13  
29  
32  
45  
46  
49  
42  
7
34  
36  
37  
40  
2
1
33  
3
6720608124-10.1 JF  
Fig. 28 Components Diagram  
25  
6 720 608 124  
 
Interior components and diagram parts list  
8.3 Parts list  
Item  
1
Description  
Front cover  
Reference  
8 705 431 243 0  
8 705 506 759 0  
8 702 000 304 0  
8 705 505 438 0  
8 705 504 150 0  
8 708 003 190 0  
8 700 506 200 0  
8 705 406 330 0  
8 700 715 036 0  
8 708 120 504 0  
8 708 120 617 0  
8 705 209 062 0  
8 701 201 019 0  
8 748 107 089 0  
8 700 707 369 0  
8 740 609 002 0  
8 700 507 067 0  
8 707 021 262 0  
8 707 021 279 0  
8 705 502 067 0  
8 701 004 044 0  
8 708 200 326 0  
8 708 200 327 0  
8 708 500 301 0  
8 708 500 359 0  
8 708 500 358 0  
8 707 201 028 0  
8 703 305 283 0  
8 708 008 069 0  
8 701 000 387 0  
8 707 406 083 0  
8 707 406 084 0  
8 707 006 286 0  
8 703 204 051 0  
8 700 503 079 0  
8 700 306 110 0  
8 708 500 332 0  
8 708 108 051 0  
8 701 302 181 0  
8 704 401 040 0  
8 707 202 083 0  
8 707 206 445 0  
8 701 004 043 0  
8 700 103 658 0  
8 700 306 148 0  
8 700 306 187 0  
8 700 507 059 0  
8 700 703 139 0  
8 701 201 020 0  
8 703 502 039 0  
8 705 705 034 0  
8 707 206 017 0  
8 707 206 132 0  
8 708 205 279 0  
8 700 715 178 0  
8 700 715 351 0  
8 705 500 105 0  
2
Shield  
3
Temp. control knob  
Draft Diverter  
4
5
Exhaust pipe union Ø128  
Angle bracket  
6
7
Cover retaining clip (x10)  
Heat exchanger  
Cold water pipe  
Main burner NG  
Main burner LP  
Connector  
8
9
10  
10  
11  
12  
13  
14  
15  
16  
17  
17  
18  
19  
20  
20  
21  
22  
22  
23  
24  
25  
26  
27  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
49  
50  
51  
52  
Piezo clip (x10)  
Sparking plug  
Pilot gas pipe  
Tube (x10)  
Pilot screen  
Gas valve LP  
Gas valve NG  
Throttle housing  
Washer (x10)  
Pilot injector LP  
Pilot injector NG  
Pilot valve  
Poppet valve head (3) LP  
Poppet valve head (2) NG  
Electromagnet  
Electromagnet cap  
Valve operation housing  
Guide plate  
Gas pressure regulator LP  
Gas pressure regulator NG  
Water valve  
Watervalve pushrod (10x)  
Diaphragm (A)  
Inlet water connection  
Selector screw  
Piezo igniter  
Fixing bracket  
Ignition lead  
Thermocouple  
Flue gas safety device  
Washer (x10)  
Heat exchanger washer  
Threaded bushing  
Connector  
Water filter  
Outlet hose  
Water connection clip  
Plunger  
Volumetric water governor  
ECO  
Temperature limiter  
Venturi  
Hot water pipe  
Gas supply pipe  
Cover  
Table 5  
26  
6 720 608 124  
 
Twelve Year Limited Warranty  
9
Twelve Year Limited Warranty  
General  
costs associated with service, removal or re-installation  
of the original water heater or a replaced water heater.  
Aquastar water heaters are warranted by the  
Manufacturer (BOSCH) through BBT North America.  
BBT North America (BBTNA) will furnish a replacement  
heat exchanger and will furnish a replacement of any  
other part which fails in normal use and service within  
the applicable periods specified below, in accordance  
with the terms of this warranty. The BBTNA  
replacement will be warranted for the unexpired portion  
of the original warranty. This warranty will be valid only  
for water heaters in possession of the original purchaser  
as recorded on the warranty card.  
Note: the water heater must be free of  
damaging scale deposits and not subject  
i
to gas pressures greater than those  
shown on the rating plate, which must not  
be altered, defaced or removed.  
How to Make a Claim  
Any claim for warranty parts should be made to your  
local dealer, distributor or to BBTNA. If BBTNA, please  
contact the Technical Support Department:  
The Heat Exchanger  
BBT NORTH AMERICA  
Bosch Group  
If the heat exchanger fails within twelve (12) years after  
the original installation and operation BBTNA will  
furnish a replacement heat exchanger. However, if the  
water heater is installed in other than a single family  
dwelling this heat exchanger warranty is limited to two  
(2) years from date of original installation and operation.  
340 Mad River Park  
Waitsfield, VT 05673  
Phone: 800-642-3111  
Exceptions  
In most cases, the dealer or distributor will be able to  
promptly honor your claim and subsequently notify  
BBTNA. However, all replacements are made subject to  
validation by BBTNA of in-warranty coverage. The  
damaged or defective item must be made available in  
exchange for the replacement.  
This warranty will not apply:  
1. to defects or malfunctions resulting from failure to  
properly install, operate or maintain the unit in  
accordance with the printed instructions provided;  
2. to damage or abuse, accident, neglect or freezing  
and other acts of nature;  
Miscellaneous  
3. to damage resulting from operation with either the  
No one is authorized to make any other warranties on  
behalf of BBTNA. It is expressly understood that the  
replacement warranty of BBTNA shall be in lieu of any  
and all other warranties, express or implied, including  
warranties of merchantability or fitness for a particular  
use or purpose, and further that BBTNA shall not be  
liable for any loss or damage directly or indirectly arising  
from the use of the hot water heater, or for any  
consequential damages arising from such use  
(including damages from water leakage). BBTNA sole  
liability with respect to any defect shall be for the  
replacement of the defective part(s). Some states do  
not allow such limitations and exclusions, so the above  
may not apply to you.  
flame sensor rod or overheat sensor removed;  
4. to failure of the heat exchanger resulting from the  
operation of the water heater in a corrosive  
atmosphere or at water temperatures exceeding the  
maximum rating, or if the water heater is not supplied  
with potable water;  
5. to defects or damage cause by any attachment  
or modification, including any energy-saving device.  
All Other Parts  
If any other part fails within two (2) years after original  
installation and operation, BBTNA will furnish a  
replacement part free of charge.  
This warranty gives specific legal rights. You may also  
have other rights which vary from state to state.  
Shipping costs  
In addition to supplying the replacement part(s),  
BBTNA will provide ground service delivery for these  
parts. Expedited or upgraded shipping will be charged  
to the customer.  
Service Labor Costs  
This warranty does not cover any labor costs  
associated with service, removal or re-installation of  
part(s). All such costs must be borne by the Purchaser.  
Additionally, this warranty does not cover any labor  
27  
6 720 608 124  
 
Installer Checklist, to be performed by installer upon installation  
Serial Number  
___ ___ ___ ___ ___ ___ ___ ___  
(8 digit serial number is located on rating plate on right side panel)  
Gas Pressure Reading*  
Building Water Pressure  
Average Winter Temperature  
Average Summer Temperature  
Installing Company  
Installer name  
Static__________  
Operating__________  
__________ Range if on Well system __________  
__________  
__________  
_____________________________________________  
_____________________________________________  
_____________________________________________  
_____________________________________________  
Address  
Phone  
* See Chapter 3.8 and gas pressure table (to be filled out by installer)  
Installation manual should be left with the owner after the installation is tested and completed  
BBT NORTH AMERICA  
Bosch Group  
VULCANO Termodomésticos S.A.  
Bosch Water Heating  
340 Mad River Park  
Estrada de Cacia  
Waitsfield, VT 05673  
3801 - 856 Aveiro - PORTUGAL  
Phone 800-642-3111  
Fax 802-496-6924  
Recycled paper  
© 2006 BBT NORTH AMERICA CORPORATION,  
Waitsfield, VT all rights reserved  
 

Bionaire Fan BFH6500 User Manual
Black Box Switch KV150A R2 User Manual
Bolens Edger 240 600 User Manual
Bosch Appliances Video Gaming Accessories 9922 141 70691 en User Manual
Bosch Power Tools Drill 0601912460 User Manual
Bosch Power Tools Home Security System DSA N2B20 User Manual
Boston Acoustics Car Speaker boston mobile audio performance standard coaxial speakers User Manual
Canon Scanner Capture Perfect 30 User Manual
Casio Digital Camera EX Z3 User Manual
Christie Digital Systems Projector 25K User Manual