American Water Heater Commercial Ultra Low NOx Gas water Heater User Manual

7

Thermometers should be obtained and field installed as shown in 

Figure 3.
Thermometers are installed in the system as a means of detecting the 

temperature of the outlet water supply.

1. All piping components connected to this unit for space heating 

applications shall be suitable for use with potable water.

2. Toxic chemicals, such as those used for boiler treatment, shall 

NEVER be introduced into this system.

3.  This unit may NEVER be connected to any existing heating system 

or component(s) previously used with a non-potable water heating 

appliance.

4.  When the system requires water for space heating at temperatures 

higher than required for domestic water purposes, a tempering 

valve must be installed.  Please refer to installation diagram on 

page 6 of  this manual for suggested piping arrangements.

5.  These water heaters cannot be used in space heating applications 

only.

A closed system will exist if a check valve (without bypass), pressure 

reducing valve (without bypass), or a water meter (without bypass) 

is installed in the cold water line between the water heater and street 

main (or well).

Excessive pressure may develop in such closed systems, causing 

premature tank failure or intermittent relief valve operation.  This is not a 

warranty failure.  An expansion tank or a similar device may be required 

in the inlet supply line between the appliance and the meter or valve to 

compensate for the thermal expansion of the water.

The system installation must conform to these instructions and to the 

local code authority having jurisdiction.  Good practice requires that all 

heavy piping be supported.

This water heater is equipped with a combination temperature-pressure 

relief valve that complies with the standard for relief valves for hot water 

supply systems Z21.22-CSA 4.4. 

FOR SAFE OPERATION OF THE 

WATER HEATER, THE RELIEF VALVE(S) MUST NOT BE REMOVED 

OR PLUGGED.

ASME ratings cover pressure relief capacities. ANSI ratings cover release 

rate with temperature actuation.

In addition to the appliance relief valve, each remote storage tank 

which may be used in conjunction with this appliance shall also be 

installed with a properly sized, rated and approved combination 

temperature (ANSI) and pressure (ASME) relief valve(s). This valve 

shall comply with the standard for relief valves for hot water supply 

systems Z21.22-CSA 4.4.

THE PURPOSE OF RELIEF VALVE IS TO AVOID EXCESSIVE PRESSURE 

OR TEMPERATURE INTO THE STEAM RANGE, WHICH MAY CAUSE 

SCALDING  AT FIXTURES, TANK EXPLOSION, SYSTEM OR HEATER 

DAMAGE.  NO VALVE IS TO BE PLACED BETWEEN THE 

RELIEF 

VALVE AND TANK.

Your local code authority may have other specific relief valve 

requirements.

A DRAIN LINE MUST BE CONNECTED TO THE RELIEF VALVE TO 

DIRECT DISCHARGE TO A SAFE LOCATION TO AVOID SCALDING OR 

WATER DAMAGE.  THIS LINE MUST NOT BE REDUCED FROM THE 

SIZE OF THE VALVE OUTLET AND MUST NOT CONTAIN VALVES, 

RESTRICTIONS NOR SHOULD IT BE LOCATED IN FREEZING AREAS.  

DO NOT THREAD OR CAP THE END OF THIS LINE.  RESTRICTED OR 

BLOCKED DISCHARGE WILL DEFEAT THE PURPOSE OF THE VALVE 

AND IS UNSAFE.  DISCHARGE LINE SHALL BE INSTALLED TO ALLOW 

COMPLETE DRAINAGE OF BOTH THE VALVE AND LINE.

See SERVICE INFORMATION section for procedure and precautions.

The type, size and location of the relief valves must be in accordance 

with local codes.  The location of the relief valve is shown in Figure 1.  

The heater has a factory installed high temperature limit switch.

Contact your local gas service company to ensure that adequate gas service 

is available and to review applicable installation codes for your area.

Size the main gas line in accordance with Table 4. The figures shown 

are for straight lengths of pipe at 0.5 in. W.C. pressure drop, which is 

considered normal for low pressure systems.  Note:  Fittings such as 

elbows, tees and line regulators will add to the pipe pressure drop.  Also 

refer to the current edition of the National Fuel Gas Code. For Canadian 

installations consult Canadian Installation Code CAN/CSA-B149.1.

The minimum gas supply pressure for input adjustment is 6.0" kPa W.C. 

for natural gas (11.0" kPa W.C. for propane).

THE HEATER IS NOT INTENDED FOR OPERATION AT HIGHER THAN 

14" kPa WATER COLUMN SUPPLY PRESSURE. EXPOSURE TO HIGHER 

GAS SUPPLY PRESSURE MAY CAUSE DAMAGE TO THE CONTROL 

WHICH COULD RESULT IN FIRE OF EXPLOSION. 

If overpressure has 

occurred such as through improper testing of gas lines or emergency 

malfunction of the supply system, the control must be checked for safe 

operation. Make sure that the outside vents on the supply regulators 

and the safety vent valves are protected against blockage. These are 

parts of the gas supply system not the heater. Vent blockage may occur 

during ice storms.

IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING FROM 

CONTAMINANTS IN THE GAS WAYS.  SUCH FOULING MAY CAUSE 

IMPROPER OPERATION, FIRE OR EXPLOSION.

IF COPPER SUPPLY LINES ARE USED THEY MUST BE INTERNALLY 

TINNED AND CERTIFIED FOR GAS SERVICE. BEFORE ATTACHING THE 

GAS LINE, BE SURE THAT ALL GAS PIPE IS CLEAN ON THE INSIDE.

TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS SUPPLY 

LINE, A DIRT LEG (SOMETIMES CALLED SEDIMENT TRAP OR DRIP 

LEG) MUST BE INCORPORATED IN THE PIPING (SEE FIG. 5).  THE 

DIRT LEG MUST BE READILY ACCESSIBLE AND NOT SUBJECT 

TO FREEZING CONDITIONS. INSTALL IN ACCORDANCE WITH 

RECOMMENDATIONS OF SERVING GAS SUPPLIERS.  REFER 

TO THE CURRENT EDITION OF THE NATIONAL FUEL GAS CODE.  

For Canadian installations consult Canadian Installation Code CAN/

CSA-B149.1.

To prevent damage, care must be taken not to apply too much torque 

when attaching gas supply pipe to gas valve inlet.

Apply joint compounds (pipe dope) sparingly and only to the male threads 

of pipe joints.  Do not apply compounds to the first two threads.  Use 

compounds resistant to the action of liquefied petroleum gases.