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General Instructions
A manual water control valve must be placed in the
water inlet connection to the water heater before it is
connected to the water line. Unions may be used on
both the hot and cold water lines for future servicing
and disconnection of the unit.
• The piping (including soldering materials) and
components connected to this appliance must be
approved for use in potable water systems.
• Purge the water line to remove all debris and air.
Debris will damage the water heater.
• Toxic chemicals such as those used for boiler water
treatment are not to be introduced to the potable
water used for space heating.
• If the appliance will be used as a potable water
source, it must not be connected to a system that
was previously used with a nonpotable water heating
appliance.
• Ensure that the water filter on the water heater is clean
and installed (See Flushing the Heat Exchanger).
Pressure Relief Valve
• An approved pressure relief valve is required by the
American National Standard (ANSI Z21.10.3) / Canadian
Standard (CSA 4.3) for all water heating systems.
• The relief valve must comply with the standard for Relief
Valves and Automatic Gas Shutoff Devices for Hot Water
Supply Systems ANSI Z21.22 and /or the standard
Temperature, Pressure, Temperature and Pressure
Relief Valves and Vacuum Relief Valves, CAN1-4.4.
• The relief valve must be rated up to 150 psi and to at
least the maximum BTU/hr of the appliance.
• The discharge from the pressure relief valve should
terminate a maximum of six inches above a floor
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. Follow local
codes. Water discharged from the relief valve could
cause severe burns instantly, scalds, or death.
• The pressure relief valve must be manually operated
once a year to check for correct operation.
• The relief valve should be added to the hot water outlet
line according to the manufacturer's instructions. DO
NOT place any other type valve or shut off device
between the relief valve and the water heater.
Do not plug the relief valve and do not install any
reducing fittings or other restrictions in the relief line
The relief line should allow for complete drainage of the
valve and the line.
If a relief valve discharges periodically, this may be due
to thermal expansion in a closed water supply system.
Contact the water supplier or local plumbing inspector on
how to correct this situation. Do not plug the relief valve.
• Neither this water heater nor the American National
Standard (ANSI Z21.10.3) / Canadian Standard (CSA
4.3) requires a combination temperature and pressure
relief valve for this appliance. However, local codes
may require a combination temperature and pressure
relief valve.
Freezing Protection
The freeze protection features include electrical heating
elements and intermittent firing of the burner. Freeze
protection may be disabled if electricity or gas is not
supplied, or if there is an error preventing the water
heater from functioning. Loss of freeze protection may
result in water damage from a burst heat exchanger or
water lines.
The installation of auto drain down solenoid valves is
optional. However, it is strongly recommended that
these valves be installed to prevent damage from
freezing in case the normal freeze protection should
become disabled. Any product damage due to freezing
will not be covered by the warranty.
In addition, the solenoid valves should be connected
electrically to a surge protector with terminals that
attaches to the PC board in the unit. This allows the
solenoid valves to operate if the water heater is disabled
due to an error code.
The solenoid valves and the surge protector with
terminals are available for purchase separately.
NOTICE: Warranty does not cover damage due to
freezing.
When electrical power and gas are supplied to the
water heater, it will not freeze in environments as cold
as -30 ° F when protected from direct wind exposure.
In the event of a power failure at temperatures below
freezing the water heater should be drained of all water
to prevent freezing damage.
The unit may be drained manually. However, it is highly
recommended that drain down solenoid valves be
installed that will automatically drain the unit if power is
lost. It is also recommended that a surge protector with
terminals be installed that attaches to the PC board in
the unit and allows the solenoid valves to operate if the
unit is disabled due to an error code.
When the electrical power to the water heater fails, the
3/4" solenoid valve closes (stopping the flow of water
into the heater) and the 1/2" solenoid valve opens
(allowing the water heater and associated piping to
drain. Ensure that you run the drain for the solenoids to
the outside environment to prevent discharging water
inside the building causing water damage).
305 & 505 Indoor Manual 13