American Water Heater 40 Gallon 38000 BTU Direct Vent Natural Gas Water Heater DVG6240S38NOV user manual

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LOCATING THE NEW WATER HEATER
 
 FACTS TO CONSIDER ABOUT THE LOCATION
Carefully choose an indoor location for the new water 
heater because the placement is a very important 
consideration for the safety of the occupants in the building 
and for the most economical use of the appliance. This 
water heater is not for use in manufactured (mobile) homes 
or outdoor installation.
Whether replacing an old water heater or putting the water 
heater in a new location, the following critical points must 
be observed:
1.  Select a location indoors as close as practical to the 
vent termination position. Figure 28 shows the venting 
distances that the heater can be from the outside wall. 
Ensure the vent termination position maintains the 
clearances as outlined in Figure 28 thru Figure 30.
2.  Selected location must provide adequate clearances 
for servicing and proper operation of the water heater.
3.  Avoid locations that could cause the water heater to 
freeze from outside air.
4.  Avoid locations that expose the water heater to direct 
sunlight.
5.  Keep combustibles such as boxes, magazines, 
clothes, etc., away from the water heater area.
• All water heaters eventually leak.
• Do not install without adequate drainage.
Property Damage Hazard
CAUTION
Installation of the water heater must be accomplished in 
such a manner that if the tank or any connections should 
leak, the fl ow of water will not cause damage to the 
structure. For this reason it is not advisable to install the 
water heater in an attic or upper fl oor. In all cases, a metal 
drain pan should be installed under the water heater. Metal 
drain pans are available at your local hardware store. Such 
a metal drain pan must have a clearance of at least  1”  
greater than any point on the water heater’s outer jacket 
and must be piped to an adequate drain. The pan must 
have a maximum depth of  1.75” .
Water heater life depends upon water quality, water 
pressure and the environment in which the water heater 
is installed. Water heaters are sometimes installed in 
locations where leakage may result in property damage, 
even with the use of a metal drain pan piped to a drain. 
However, unanticipated damage can be reduced or 
prevented by a leak detector or water shut-off device used 
in conjunction with a piped metal drain pan. These devices 
are available from some plumbing supply wholesalers and 
retailers, and detect and react to leakage in various ways:
• Sensors mounted in the metal drain pan that trigger an 
alarm or turn off the incoming water to the water heater 
when leakage is detected.
• Sensors mounted in the metal drain pan that turn off 
the water supply to the entire building when water is 
detected in the metal drain pan.
• Water supply shut-off devices that activate based on 
the water pressure differential between the cold water 
and hot water pipes connected to the water heater.
• Devices that will turn off the gas supply to a gas water 
heater while at the same time shutting off its water 
supply.
 EXTERNAL/INTERNAL  DAMAGE
Do not operate the water heater until it has been fully 
checked out by a qualifi ed technician, if the water heater:
• Has been exposed to fi re or damage.
• Displays evidence of sooting.
• Produces steam or unusually hot water.
If the water heater has been fl ooded it must be replaced. 
						

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 AIR  REQUIREMENTS
For safe operation an adequate supply of fresh, 
uncontaminated air must be provided for combustion.
This gas-fi red water heater is a direct vent model. It 
connects directly to the outside of the building through 
the vent termination hood. The hood operates as both 
the combustion air intake and the heater exhaust port 
(see Figure 16).
All combustion air is obtained from outside the building 
through this hood. Ensure the area around the termination 
hood is always kept clear and that the air supply is not 
exposed to contamination or fl ammable vapo rs.
 CONFINED SPACE INSTALLATIONS
This water heater connects to the vent termination hood 
using the sealed air intake and exhaust piping (see Figure 
1 and Figure 2).
During operation this piping can become hot, especially in 
areas experiencing high ambient temperatures.
When installed in a confi ned space such as a closet, it is 
recommended that the confi ned space be ventilated to 
minimize the buildup of heat around the heater. Figure 6 
and Figure 7 show an examples of ventilating a confi ned 
space.
  0”  MIN.   0”  MIN.
  0”  MIN.
  5.5”  MIN.
TOP VIEW 
OF CLOSET 
WITHOUT DOORTOP VIEW OF 
CLOSET WITH 
DOOR
Figure 6 
FRONT VIEW 
OF DOORROOM AIR 
FLOW
ROOM AIR 
FLOW
VENTILATION
AIR
OPENING
Figure 7 
 Clearances To Combustibles
Minimum clearances between water heater and 
combustibles are  0”  at the sides and rear,  5.5”  from the 
front and  12”  from top. Minimum clearances from vent 
piping to combustibles is  1”  except as noted in Figure 
21. If clearances stated on the heater differ from these 
clearances, install water heater according to clearances 
stated on the heater (see Figure 6).
 Floors With Carpeting
This water heater must not be installed directly on 
carpeting. Carpeting must be protected by a metal or 
wood panel beneath the appliance extending beyond 
the full width and depth of the appliance by at least  3”  in 
every direction, or if the appliance is installed in an alcove 
or closet, the entire fl oor must be covered by the panel. 
Failure to heed this warning may result in a fi re hazard.
 Clearance For Servicing
Adequate clearance of  24”  for servicing this appliance 
should be considered before installation, such as changing 
the anodes, etc.
A minimum clearance of  5.5”  must be allowed for access 
to replaceable parts such as thermostats, drain valve and 
relief valve.
When installing the heater, consideration must be given to 
proper location. Location selected should be as close to 
the wall as practicable and as centralized with the water 
piping system as possible.
 CHEMICAL  VAPO R CORROSION
CORROSION OF THE FLUEWAYS AND VENT SYSTEM 
MAY OCCUR IF AIR FOR COMBUSTION CONTAINS 
CERTAIN CHEMICAL VAPO RS. SUCH CORROSION 
MAY RESULT IN FAILURE AND RISK OF ASPHYXIATION.
Spray can propellants, cleaning solvents, refrigerator and 
air conditioning refrigerants, swimming pool chemicals, 
calcium and sodium chloride (water softener salt), waxes, 
and process chemicals are typical compounds which are 
potentially corrosive. Do not store products of this sort 
near the heater or the vent termination hood. Air which is 
brought in contact with the heater or the vent termination 
hood should not contain any of the chemicals. The Limited 
Warranty is voided when failure of water heater is due 
to a corrosive atmosphere. See “Limited Warranty” for 
complete terms and conditions.
Read instruction manual before 
installing, using or servicing 
water heater. • Do not store or use gasoline or other flammable vapors and 
liquids in the vicinity of this water heater, the vent termina-
tion hood, or any other appliance.
• Avoid all ignition sources if you smell gas.
• Do not expose water heater control to excessive gas 
pressure.
• Use only gas shown on rating plate.
• Maintain required clearances to combustibles.
• Keep ignition sources away from faucets after extended 
period of non-use.
Fire or Explosion Hazard
WARNING
    
						

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FLAMMABLE
Do not store or use gasoline or other flammable vapors and 
liquids in the vicinity of this or any other appliance.  Storage or 
use of gasoline or other flammable vapors or liquids in the 
vicinity of this or any other appliance can result in serious injury 
or death.
Can result in serious injury or deathFIRE AND EXPLOSION HAZARD
Flammable VaporsFLAMMABLES
WARNING
For continued protection against 
risk of fire:
• Do not install water heater on 
carpeted floor.
• Do not operate water heater if 
flood damaged.Fire Hazard
WARNING
   
 STORAGE OF FLAMMABLE LIQUIDS
Flammable liquids (such as gasoline, solvents, propane 
(LP or butane, etc.) and other substances (such as 
adhesives, paints, etc.) emit fl ammable vapo rs which can 
be ignited by a gas water heater’s pilot or main burner. The 
resulting fl ashback  and fi re can cause death or serious 
burns to anyone in the area.
Even though this water heater is a fl ammable  vapo rs 
ignition resistant (FVIR) water heater and is designed to 
reduce the chances of fl ammable  vapo rs being ignited, 
gasoline and other fl ammable substances should never 
be stored or used in the same vicinity or area containing a 
gas water heater, the vent termination hood, or other open 
fl ame or spark producing appliance. Examples of such 
locations are garages, storage and utility areas.
The water heater must be located and/or protected so it 
is not subject to physical damage by a moving vehicle.
Propellants of aerosol sprays and volatile compounds, 
(cleaners, chlorine based chemicals, refrigerants, etc.) in 
addition to being highly fl ammable in many cases, will also 
react to form corrosive hydrochloric acid when exposed to 
the combustion products of the water heater. The results 
can be hazardous, and also cause product failure.
 INSULATION  BLANKETS
Insulation blankets are available to the general public for 
external use on gas water heaters but are not necessary 
with these products. The purpose of an insulation blanket 
is to reduce standby heat loss encountered with storage 
tank heaters. Your water heater meets or exceeds 
the current standards with respect to insulation and 
standby loss requirements, making an insulation blanket 
unnecessary.  Should you choose to apply an insulation 
blanket to this heater, you should follow these instructions 
(For identifi cation of components mentioned below, see 
Figure 1 thru Figure 5). Failure to follow these instructions 
will restrict the air fl ow required for proper combustion and 
dilution, potentially resulting in fi re, asphyxiation, serious 
personal injury or death.
• Check local codes to determine if insulation blankets 
are allowed.
• Do not cover the outer door, thermostat or T&P relief 
valve.
• Do not cover the “Installation And Operating manual”. 
Keep it on the side of the water heater or nearby for 
future reference.
• Do obtain new warning and instruction labels from the 
manufacturer for placement on the blanket directly over 
the existing labels. 
						

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 WATER  PIPING
 Water  Pressure
The water supply pressure should not exceed 80 psi. If this 
occurs, a pressure reducing valve with a bypass should be 
installed in the cold water inlet line. This should be placed 
on the supply to the entire house in order to maintain equal 
hot and cold water pressures. See also “Closed Water 
Systems” and “Thermal Expansion” sections.
 Mixing  Valves
HOT WATER CAN SCALD:
Water heaters are intended to heat water. Water heated 
to a temperature which will satisfy space heating, clothes 
washing, dish washing, cleaning and other sanitizing 
needs can scald and permanently injure you upon contact.
Short repeated heating cycles caused by small hot water 
uses can cause a temperature increase of the hot water 
by  20F°  higher than the heater’s temperature settings.
MIXING VALVE
SHUT-OFF 
VA LV E
SUGGESTED PIPING 
ARRANGEMENT FOR 
TOP CONNECTIONS
COLD WATER 
INLETTEMPERED 
POTABLE WATER
DISCHARGE 
PIPE (DO NOT 
CAP OR PLUG)
GAS 
SUPPLY
TEMPERATURE-
PRESSURE 
RELIEF VALVE
DRAIN 
VA LV E
METAL DRAIN 
PA N
  6 ”  MAX. 
AIR GAP*
CERTAIN 
MODELS ARE 
EQUIPPED WITH 
SIDE PLUMBING 
CONNECTIONS 
FOR SPACE 
HEATING. THE HOT 
AND COLD FITTING 
ASSEMBLIES 
(PART #9001262) 
CAN BE ORDERED 
THROUGH THE 
MANUFACTURER
MASSACHUSETTS: INSTALL A VACUUM RELIEF IN COLD-WATER LINE 
PER SECTION 19 MGL 142.
Figure 8 
Water temperature over 
125°F can cause severe 
burns instantly resulting in 
severe injury or death.
Children, the elderly and the 
disabled and are at highest 
risk of scald injury.
Feel water before bathing or 
showering.
Temperature limiting devices 
such as mixing must be 
installed when required by 
codes and to ensure safe 
temperatures at fixtures.
BURN
HOT
HOT
DANGER
 
Some people are more likely to be permanently injured 
by hot water than others. These include the elderly, 
children, the infi rm and the physically/mentally disabled. 
Table 1 (published by U.S. Government Memorandum, 
1978) shows the approximate time-to-burn relationship 
for normal adult skin. If anyone using hot water provided 
by the water heater being installed fi ts into one of these 
groups or if there is a local code or state law requiring a 
certain water temperature at the point of use, then special 
precautions must be taken (see Figure 8).
Water 
Temperature 
  °F Time for 1st
Degree Burns
(Less Severe Burns)Time for Permanent 
Burns 2nd & 3rd 
Degree (Most 
Severe Burns)
  110  (normal shower temp.)
  116 (pain threshold)
  116  35 minutes 45 minutes
  122  1 minute 5 minutes
  131  5 seconds 25 seconds
  140  2 seconds 5 seconds
  149  1 second 2 seconds
  154 instantaneous 1 seconds
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, 
Sept. 15,1978)
Table 1 
In addition to using lowest possible temperature setting 
that satisfi es demand of application, a mixing valve should 
be installed at the water heater (see Figure 8) or at hot 
water taps to further reduce system water temperature.
Mixing valves are available at plumbing supply stores. 
Consult a Qualifi ed Installer or Service Agency. Follow 
mixing valve manufacturer’s instructions for installation 
of the valves. Before changing the factory setting on the 
thermostat, read the “Operating The Temperature Control 
System” section in this manual.  
						

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INSTALLING THE NEW WATER HEATER
 WATER PIPING INSTALLATION
Note: Water piping and vent piping occupy the space 
above the water heater. Plan the water piping to ensure 
it does not cause interference with the vent piping (see 
“Venting”).
• The system should be installed only with piping that is 
suitable for potable (drinkable) water such as copper, 
CPVC, or polybutylene. This water heater must not be 
installed using iron piping or PVC water piping.
• Use only pumps, valves, or fi ttings that are compatible 
with potable water.
• It is recommend that only full fl ow ball or gate valves 
are used in water piping installations. The use of valves 
that may cause excessive restriction to water fl ow  is 
not recommended.
• Use only 95/5 tin-antimony or other equivalent solder. 
Any lead based solder must not be used.
• Piping that has been treated with chromates, boiler 
seal, or other chemicals must not be used.
• Chemicals that may contaminate the potable water 
supply must not be added to the piping system.
Piping, fi ttings, and valves should be installed according 
to the installation drawing (see Figure 9). If the indoor 
installation area is subject to freezing temperatures, the 
water piping must be protected by insulation.
Important: Heat must not be applied to the water fi ttings on 
the heater as they may contain nonmetallic parts. If solder 
connections are used, solder the pipe to the adapter before 
attaching the adapter to the hot and cold water fi ttings.
Important: Always use a good grade of joint compound 
and be certain that all fi ttings are drawn up tight.
1.  Install the water piping and fi ttings as shown in Figure 
9. Connect the cold water supply (3/4” NPT) to the cold 
water inlet fi tting. Connect the hot water supply (3/4” 
NPT) to the hot water outlet fi tting.
Important: These models may contain energy saving heat 
traps to minimize the migration of heat to the pipes. Do 
not remove the inserts within the heat traps.
2.  The installation of unions in both the hot and cold water 
supply lines is recommended for ease of removing the 
water heater for service or replacement.
3.  If installing the water heater in a closed water system, 
install an expansion tank in the cold water line as 
specifi  ed under “Closed Water Systems” and “Thermal 
Expansion”.
4.  Install a shut-off valve in the cold water inlet line. It 
should be located close to the water heater and be 
easily accessible. Know the location of this valve and 
how to shut off the water to the heater.
5.  After piping has been properly connected to the water 
heater, remove the aerator at the nearest hot water 
faucet. Open the hot water faucet and allow the tank 
to completely fi ll with water. To purge the lines of 
any excess air, keep the hot water faucet open for 
3 minutes after a constant fl ow of water is obtained. 
Close the faucet, reinstall the aerator and check all 
connections for leaks. Repair as needed.
METAL 
DRAIN 
PA N
FLOOR
DRAIN
HOT WATER 
OUTLET
COLD 
WATER 
INLET UNION
UNION 3/4” SWEAT 
FITTING
3/4” SWEAT 
FITTING
TEMPERATURE-
PRESSURE 
RELIEF VALVE
DISCHARGE PIPE
(DO NOT CAP 
OR PLUG)
  6 ”  MAX.
AIR GAPDRAIN
VA LV E SHUT-OFF 
VA LV E
SOME 
COMPONENTS 
NOT SHOWN 
FOR CLARITY.
EXPANSION 
TANK
Figure 9 
Figure 9 shows typical attachment of water piping to the 
water heater. The water heater is equipped with 3/4” NPT 
water connections.
   CLOSED WATER SYSTEMS
Water supply systems may, because of code requirements 
or such conditions as high line pressure, among others, 
have installed devices such as pressure-reducing valves, 
check valves, and back fl ow preventers. Devices such 
as these cause the water system to be a closed system.
   THERMAL  EXPANSION
As water is heated, it expands (thermal expansion). In a 
closed system, the volume of water will increase when 
heated. As the volume of water increases, there will be a 
corresponding increase in water pressure due to thermal 
expansion. Thermal expansion can cause premature tank 
failure (leakage). This type of failure is not covered under 
the limited warranty. Thermal expansion can also cause 
intermittent temperature-pressure relief valve operation: 
water discharged from the valve due to excessive pressure 
build up. The temperature-pressure relief valve is not 
intended for the constant relief of thermal expansion. This 
condition is not covered under the limited warranty.  
						

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A properly-sized and charged thermal expansion tank must 
be installed on all closed systems to control the harmful 
effects of thermal expansion. Contact a plumbing service 
agency or your retail supplier regarding the installation of 
a thermal expansion tank.
Note: To protect against untimely corrosion of hot and cold 
water fi ttings, it is recommended that di-electric unions or 
couplings be installed on this water heater when connected 
to copper pipe.
• Avoid water heater damage.
• Install thermal expansion tank if necessary.
• Do not apply heat to cold-water inlet or hot-water outlet.
• Contact qualified installer or service agency.
Property Damage Hazard
CAUTION
 
 TEMPERATURE-PRESSURE RELIEF VALVE
• Temperature-pressure relief 
valve must comply with ANSI 
Z21.22-CSA4.4 and ASME 
code.
• Properly sized temperature-
pressure relief valve must be 
installed in opening provided.
• Do not plug, block, or cap the 
discharge line.
• Failure to follow this warning 
can result in excessive tank 
pressure, serious injury or 
death.
Explosion Hazard
WARNING
This water heater is provided with a properly rated/sized 
and certifi ed combination Temperature-Pressure Relief 
Valve (T&P valve) by the manufacturer. The valve is 
certifi ed by a nationally recognized testing laboratory 
that maintains periodic inspection of production of listed 
equipment of materials as meeting the requirements for 
Relief Valves for Hot Water Supply Systems, ANSI 
Z21.22-CSA 4.4, and the code requirements of ASME.
If replaced, the new T&P valve must meet the requirements 
of local codes, but not less than a combination temperature-
pressure relief valve rated/sized and certifi ed as indicated 
in the above paragraph. The new valve must be marked 
with a maximum set pressure not to exceed the marked 
hydrostatic working pressure of the water heater (150 psi) 
and a discharge capacity not less than the water heater 
Btu/hr input rate as shown on the water heater’s model 
rating plate.
For safe operation of the water heater, the temperature-
pressure relief valve must not be removed from its designated opening nor plugged. The T&P valve must be 
installed directly into the fi  tting of the water heater designed 
for the relief valve. Install discharge piping so that any 
discharge will exit the pipe within  6 ” above an adequate 
fl oor drain, or external to the building. In cold climates it is 
recommended that it be terminated at an adequate drain 
inside the building. Be certain that no contact is made with 
any live electrical part.
The discharge opening must not be blocked or reduced 
in size under any circumstances. Excessive length (over 
  30’ ), or use of more than four elbows can cause restriction 
and reduce the discharge capacity of the valve.
No valve or other obstruction is to be placed between the 
T&P valve and the tank. Do not connect discharge piping 
directly to the drain unless a maximum of  6 ” air gap is 
provided. To prevent bodily injury, hazard to life, or property 
damage, the relief valve must be allowed to discharge 
water in adequate quantities should circumstances 
demand. If the discharge pipe is not connected to a drain 
or other suitable means, the water fl  ow may cause property 
damage.
• Temperature-pressure relief valve discharge pipe 
must terminate at an adequate drain.Water Damage Hazard
CAUTION
 T&P Valve Discharge Pipe Requirements:
• Shall not be smaller in size than the outlet pipe size 
of the valve, or have any reducing couplings or other 
restrictions.
• Shall not be plugged or blocked.
• Shall not be exposed to freezing temperatures.
• Shall be of material listed for hot water distribution.
• Shall be installed so as to allow complete drainage 
of both the temperature-pressure relief valve and the 
discharge pipe.
• Must terminate a maximum of  6 ”  above a fl oor  drain 
or external to the building. In cold climates, it is 
recommended that the discharge pipe be terminated 
at an adequate drain inside the building
• Shall not have any valve or other obstruction between 
the relief valve and the drain.
• Burn hazard.
• Hot water discharge.
• Keep clear of 
temperature-pressure 
relief valve discharge.
BURN
HOT
HOT
DANGER 
						

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The T&P valve must be manually operated at least once 
a year. Caution should be taken to ensure
1.  no one is in front of or around the outlet of the 
discharge line, and
2.  the water manually discharged will not cause any 
bodily injury or property damage because the water 
may be extremely hot.
If after manually operating the valve, it fails to completely 
reset and continues to release water, immediately close 
the cold water inlet to the water heater, follow the draining 
instructions in this manual, and replace the temperature-
pressure relief valve with a properly rated/sized new one.
Note: The purpose of a temperature-pressure relief valve 
is to prevent excessive temperatures and pressures in 
the storage tank. The T&P valve is not intended for the 
constant relief of thermal expansion. A properly sized 
thermal expansion tank must be installed on all closed 
systems to control thermal expansion, see “Closed Water 
Systems” and “Thermal Expansion” sections.
 Temperature-Pressure Relief Valve And Pipe 
Insulation
The T&P valve installed on this water heater is covered by 
insulation to minimize heat loss. The insulation has a hole 
on the bottom side to accommodate the valve outlet and 
allow for the piping connection. Do not restrict the outlet 
opening of the T&P valve.
T&P Relief Valve
T&P Relief Valve
Drain LineManual Relief Lever
T&P Relief Valve Insulation
(Outlet opening on underside)
Figure 10 
Locate the temperature and pressure relief valve on the 
water heater (also known as a T&P relief valve) (see 
Figure 10).
1.  Locate the slit running the length of the T&P relief 
valve insulation.
2.  Spread the slit open and fi t the insulation over the T&P 
relief valve (see Figure 10). Apply gentle pressure to 
the insulation to ensure that it is fully seated on the 
T&P Relief Valve. Once seated, secure the insulation 
with duct tape, electrical tape, or equivalent.
Important: The insulation and tape must not block the 
discharge opening or hinder access to the manual relief 
lever (Figure 10). Ensure a discharge pipe is installed into 
the T&P valve discharge opening per the instructions in 
this manual.
1.  Locate the hot water (outlet) and cold water (inlet) 
pipes to the water heater.
2.  Locate the slit running the length of a section of pipe 
insulation.
3.  Spread the slit open and slip the insulation over the 
cold water (inlet) pipe. Apply gentle pressure along 
the length of the insulation to ensure that it is fully 
seated around the pipe. Also, ensure that the base 
of the insulation is fl ush with the water heater. Once 
seated, secure the insulation with duct tape, electrical 
tape, or equivalent.
4.  Repeat steps 2 and 3 for the hot water (outlet) pipe.
5.  Add additional sections of pipe insulation as needed.
   FILLING THE WATER HEATER
• Avoid water heater damage.
• Fill tank with water before operating.Property Damage Hazard
CAUTION
• Never use this water heater unless it is completely full 
of water. To prevent damage to the tank, the tank must 
be fi lled with water. Water must fl ow from the hot water 
faucet before turning “ON” gas to the water heater.
To  fi ll the water heater with water:
1.  Close the water heater drain valve by turning handle 
to the right (clockwise). The drain valve is on the lower 
front of water heater (see Figure 9).
2. Important: If the heater is equipped with plumbing 
side taps and they are not connected to piping, ensure 
the side taps have been closed with pipe plugs.
3.  Open all hot water faucets served by the water heater 
to allow air to escape from the tank and the water 
piping. Ensure any shut-off valves between the heater 
and the faucets are in the open position.
4.  Open the cold water supply valve to the water heater.
Notes:
• The cold water supply valve must be left open when 
the water heater is in use.
• Avoid water leakage when fi lling the tank. Do not 
allow the insulation of the water heater to get wet as 
water can reduce the effectiveness of the insulation.
5.  Allow water to run until a constant fl ow is obtained. 
This will let air out of the water heater and the piping.
6.  Check all water piping and connections for leaks. 
Repair as needed. 
						

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 SPACE HEATING AND POTABLE WATER SYSTEMS
This appliance has been design certifi ed as complying 
with American National Standard/CSA Standard for water 
heaters and are considered suitable for Water (Potable) 
Heating and Space Heating. Note: This water heater 
may be used in combination potable water/space heating 
system. Do not use in a space heating only application.
Toxic Chemical Hazard
WARNING
• Do not connect to non-potable water system.
Note: Ensure the water heater has been properly sized 
to accommodate the needs of the hot water demand and 
space heating load. Undersizing the water heater can 
result in insuffi cient hot water, excessive condensation 
and ineffi cient operation.
• This water heater should not be connected to any 
heating systems or components previously used with 
a non-potable water heating appliance.
• All piping components connected to this unit for space 
heating applications should be suitable for use with 
potable water.
• Pumps, valves, piping and fi ttings must be compatible 
with potable water.
• Toxic chemicals, such as those used for boiler treatment 
shall not be introduced into the potable water used for 
space heating.
• When the system requires water for space heating at 
temperatures higher than required for domestic water 
purposes, a mixing valve must be installed. Please refer 
to Figure 8 for suggested piping arrangement.
• Be sure to follow the manual(s) shipped with the air 
handler or other type heating system.
• This water heater is not to be used as a replacement 
for an existing boiler installation.
• Do not use with piping that has been treated with 
chromates, boiler seal or other chemicals and do not 
add any chemicals to the water heater piping.
• A properly installed fl ow control valve is required to 
prevent thermosiphoning. Thermosiphoning is the 
result of a continuous fl ow of water through the air 
handler circuit during the off cycle. Weeping (blow off) 
of the temperature-pressure relief valve (T&P) or higher 
than normal water temperatures are the fi rst signs of 
thermosiphoning.
• The hot water line from the water heater should be 
vertical past any mixing valve or supply line to the 
heating system to remove air bubbles from the system. 
						

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 COMBO  HEATING
This section serves as a guide for the installation and use 
of “Combo” heating systems utilizing a domestic water 
heater that has been specifi cally approved for such use. 
It is written for those knowledgeable in the required trades 
and professionals involved in the design and installation 
of Combo Heating Systems.
It is the responsibility of the installer/designer to follow all 
applicable codes to ensure the effectiveness and safety 
of the installation.
 System  Requirements
The following requirements must be met for the installation 
of Combo Heating Systems:
1.  All components used for the distribution of water in 
the heating loop must be suitable for potable water. 
These include all piping, fi ttings, solder and fl uxes, 
pumps for circulation of water, valves, etc.
2.  The water heater must not be connected to a hydronic 
heating system that has been used previously.
3.  No boiler treatment chemicals of any kind shall be 
introduced into the system.
4.  The Combo System components must be selected 
and sized to meet and maintain the total calculated 
demands for both domestic service hot water 
and space heating requirement. The sizing and 
installation must be performed in accordance with 
good engineering practice such as “ASHRAE 
Handbooks”, HRAI’s Unifi ed Combo Guidelines, 
“Hydronics Institute Manuals”, ANSI Z223.1, CSA 
F280, National/Provincial Building Codes, ANSI 
and/or codes having jurisdiction.
5.  The air handler (fan coil) and/or the circulating pump 
in a baseboard hydronic loop will require a dedicated 
120V circuit. This must be provided and identifi ed for 
this purpose.
6.  All piping between the water heater and the air handler 
or hydronic baseboard loop must be adequately 
insulated to reduce heat loss.
7.  If the local jurisdiction requires a back-fl ow preventer 
in the cold water line, an expansion tank of adequate 
size must be installed.
8.  “Combo” Heating Systems require higher water 
temperatures than other applications. When the 
system is used to supply water for Combo Heating 
applications, a means, such as mixing valve, must be 
installed to temper the water in order to reduce scald 
hazard potential (see Figure 11 & Figure 12).
 Installation
The heating mode may be one of the following options:
A.  A fan coil/air handler (Figure 11).
B.  A hydronic baseboard (fi  nned tube) loop/In fl oor heating 
(Figure 12).
The following is a list of requirements for the installation 
of option A or B.
1.  Install shut-off valves and unions so that the water 
heater can be isolated from the heating module should 
servicing of the water heater become necessary.2.  Install a drain valve at the lowest point of the heating 
loop so that water can be drained from the heating 
module without affecting the water heater.
3.  If the air handler does not have a venting means at 
the highest point of the piping arrangement, install 
an air bleed at the highest point of the plumbing 
arrangement.
WATER 
HEATER 8 in TO 
12 in MAX.
HOT 
OUTLETEXPANSION TANK (OPTIONAL)
MIXING 
VA LV E
COLD INLET CHECK VALVE (IF USED 
REQUIRES EXPANSION TANK) COLD SUPPLY
HOSE BIB 
(OPT.) FLOW 
CONTROL
SUPPLYRETURN CHECK 
VA LV E
EXTERNAL 
CIRCULATOR
AIR 
HANDLER HOT WATER 
TO HOUSE 
FIXTURE
C
H M
INTERNAL 
CIRCULATORDRAIN/
PURGE 
VA LV E
(see also 
Massachusetts 
code requirements 
on pg 8)
Figure 11 
WATER 
HEATER 8 in TO 
12 in MAX.
HOT 
OUTLETEXPANSION TANK (OPTIONAL)
MIXING 
VA LV E
COLD INLET CHECK VALVE (IF USED 
REQUIRES EXPANSION TANK) COLD SUPPLY
HOSE BIB 
(OPT.) FLOW 
CONTROL
SUPPLYRETURN CHECK 
VA LV E
EXTERNAL 
CIRCULATOR HOT WATER 
TO HOUSE 
FIXTURE
C
H M
HYDRONIC 
BASEBOARDS 
(SERIES 
CONNECTED 
SHOWN)
(see also 
Massachusetts 
code requirements 
on pg 8)
Figure 12  
						

							20 www.  
 
americanwaterheater  
 
.com  
 
 GAS  PIPING
• Do not use water heater with 
any gas other than the gas 
shown on the rating plate.
• Excessive pressure to gas 
control valve can cause serious 
injury or death.
• Turn off gas lines during 
installation.
• Contact qualified installer or 
service agency.Fire and Explosion Hazard
WARNING
Explosion Hazard
Have a qualified technician make sure that the L.P. 
gas operating pressure does not exceed 13 water 
column.
Failure to do so can result in death, explosion, or 
fire.
WARNING
Make sure the gas supplied is the same type listed on the 
model rating plate. The inlet gas pressure must not exceed 
13 inch w.c. for natural gas and propane (LP) gas. The 
minimum inlet gas pressure shown on the rating plate is 
that which will permit fi ring at rated input.
All gas piping must comply with local codes and ordinances 
or with the  
“National Fuel Gas Code” (ANSI Z223.1/NFPA 
54). Copper or brass tubing and fi ttings (except that which 
is certifi ed for gas usage) should not be used.
If the gas control valve/thermostat is subjected to 
pressures exceeding 1/2 psi (14 inch w.c.), the damage 
to the gas control valve/thermostat could result in a fi re or 
explosion from leaking gas.
If the main gas line shut-off serving all gas appliances is 
used, also turn “OFF” the gas at each appliance. Leave 
all gas appliances shut “OFF” until the water heater 
installation is complete.
A gas line of suffi cient size must be run to the water heater. 
Consult the current edition of the  
“National Fuel Gas 
Code” (ANSI Z223.1/NFPA 54) and your gas supplier 
concerning pipe size.There must be:
• A readily accessible manual shut-off valve in the gas 
supply line serving the water heater, and
• A sediment trap ahead of gas control valve/thermostat 
to help prevent dirt and foreign materials from entering 
the gas control valve/thermostat.
• A fl  exible gas connector or a ground joint union between 
the manual gas shut-off valve and gas control valve/
thermostat to permit servicing of the unit.
Be sure to check all the gas piping for leaks before lighting 
the water heater. Use a soapy water solution, not a match 
or open fl ame. Repair and retest as required. When 
fi nished, rinse off soapy solution and wipe dry.
• Use joint compound or tape 
compatible with propane.
• Leak test before operating 
heater.
• Disconnect gas piping and 
shut-off valve before pressure 
testing system.Fire and Explosion Hazard
WARNING
Use pipe joint compound or Tefl on tape marked as being 
resistant to the action of gases.
The appliance and its gas connection must be leak tested 
before placing the appliance in operation.
The appliance and its individual manual gas shut-off 
valve should be disconnected from the gas supply piping 
system during any pressure testing of that system at test 
pressures in excess of 1/2 psi. It should be isolated from 
the gas supply piping system by closing its individual 
manual gas shut-off valve during any pressure testing of 
the gas supply piping system at test pressures equal to 
or less than 1/2 psi.
Connecting gas piping to the gas control valve/thermostat 
of water heater can be accomplished by  either of two 
methods shown in Figure 13 & Figure 14.