A.O. Smith BTH 300A User Manual

15

LESS, THE APPLIANCE NEED NOT BE DISCONNECTED, BUT MUST
BE ISOLATED FROM THE SUPPLY PRESSURE TEST BY CLOSING
THE MANUAL GAS SHUTOFF VALVE.

BEFORE PLACING THE HEATER IN OPERATION, CHECK FOR
GAS LEAKAGE. USE SOAP AND WATER SOLUTION OR OTHER
MATERIAL ACCEPTABLE FOR THE PURPOSE OF  LOCATING
GAS LEAKS. DO NOT USE MATCHES, CANDLES, FLAME OR
OTHER SOURCES OF IGNITION FOR THIS PURPOSE.

Gas line purging is required with new piping or systems in which air
has entered.

PURGING SHOULD BE PERFORMED BY PERSONS
EXPERIENCED IN THIS TYPE OF GAS SERVICE. TO AVOID RISK
OF FIRE OR EXPLOSION, PURGE DISCHARGE MUST NOT
ENTER CONFINED AREAS OR SPACES WHERE IGNITION CAN
OCCUR. THE AREA MUST BE WELL VENTILATED AND ALL
SOURCES OF IGNITION MUST BE INACTIVATED OR REMOVED.

Be sure that the gas meter has sufficient capacity to supply the full
rated gas input of the water heater as well as the requirements of
all other gas fired equipment supplied by the meter. If the gas meter
is too small, ask the gas company to install a larger meter having
adequate capacity.

SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO
SHUT OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO
THE APPLIANCE.

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.

Thermometers should be obtained and field installed as shown in
the installation diagrams.

Thermometers are installed in the system as a means of detecting
the temperature of the outlet water supply.

This heater is equipped with an approved temperature and pressure
relief valve. ASME ratings cover pressure relief. CSA ratings cover
release rate with temperature actuation.

FOR SAFE OPERATION OF THE WATER HEATER, THE RELIEF
VALVE(S) MUST NOT BE REMOVED OR PLUGGED.

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

comply with the standard for relief valves and automatic gas shutoff
devices for hot water supply systems. ANSI Z21.22-CSA 4.4.

Your local code authority may have other specific relief valve
requirements.

THE PURPOSE OF A 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 THE TANK.

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 OR 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. THE DISCHARGE LINE SHALL BE INSTALLED TO
ALLOW COMPLETE DRAINAGE OF BOTH THE VALVE AND LINE.

This manual provides detailed installation diagrams (see back
section of this manual) for typical methods of application for the
water heaters.

The water heater may be installed by itself, or with a separate storage
tank. When used with a separate storage tank, the circulation may be
either by gravity or by means of circulating pump. When a circulating
pump is used, it is important to note that the flow rate should be slow so
that there will be a minimum of turbulence inside the heater.

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 causing premature tank failure or
intermittent relief valve operation. This type of failure is not covered
by the limited warranty. 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 water
under supply pressure.

If a water heater is installed in a closed water system, check local
codes or contact the water supplier or local plumbing inspector on
how to control this situation.

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 non-potable water heating
appliance.