Connection Of Gas Pipe; Purging; Gas Meter Size - City Gases Only; Gas Pressure Regulation - A.O. Smith BTH 120-250(A) Installation & Operating Instructions Manual

CONNECTION OF GAS PIPE

1. When connecting gas pipe to unit, apply wrench to flange only. Note:
Do not use wrench on gas valve or gas bracket. See Figure 15.
2. PERFORM THE GAS LEAK TEST ANY TIME WORK IS DONE ON A
GAS SYSTEM TO AVOID THE POSSIBILITY OF FIRE OR EXPLOSION
WITH PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.
The Gas Leak Test is performed as follows: Paint pipe connections upstream
of gas control with a rich soap and water solution to test for leaks before
operating main burner. Bubbles indicate gas leak. To stop leak, tighten pipe
connections. After piping connections are checked, turn on main burner.
With main burner in operation, paint pipe joints (including flanges), pilot gas
tubing connections and control inlet and outlet with rich soap and water
solution. Bubbles indicate gas leak. To stop leak, tighten flange screws,
joints and pipe connections. Replace part if leak can't be stopped.
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 compound to the first two threads. Use compounds
resistant to the action of liquefied petroleum gases.
DISCONNECT THE APPLIANCE AND ITS MANUAL GAS SHUTOFF VALVE
FROM THE GAS SUPPLY PIPING SYSTEM DURING ANY SUPPLY
PRESSURE TESTING EXCEEDING 1/2 PSIG (3.45Kpa). GAS SUPPLY LINE
MUST BE CAPPED WHEN DISCONNECTED FROM THE HEATER. FOR
TEST PRESSURES OF 1/2 PSIG (3.45Kpa) OR 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.

PURGING

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.
FIGURE 15
CAUTION

GAS METER SIZE - CITY GASES ONLY

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.

GAS PRESSURE REGULATION

Main line gas pressure to the water heater should be between a maximum
14.0" (3.45Kpa) W.C. and a minimum as shown in Table 4: that is, for
Natural Gas, 5.0" (1.25Kpa) W.C. for BTH 120 & 250 or 4.5" (1.12Kpa) W.C.
for BTH 150 & 199 or; for L.P. Gas, 11.0" (2.74Kpa) W.C. The inlet gas
pressure must not exceed the maximum value. A service regulator must be
installed within 10' (305 cm) of unit.
FAILURE TO INSTALL A PRESSURE REGULATOR WITHIN 10 FEET OF
THE WATER HEATER CAN RESULT IN LEAKAGE OF FLUE GASES INTO
THE SURROUNDING ROOM. SERIOUS PERSONAL INJURY OR DEATH
COULD RESULT FROM INHALATION OF CARBON MONOXIDE GAS.
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT
OFF, TURN OFF THE MANUAL GAS CONTROL VALVE TO THE
APPLIANCE.

SYSTEM CONNECTIONS

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 (Not Supplied)
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.

RELIEF VALVE

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 for hot water supply systems. ANSI Z21.22
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.
13
WARNING

GAS VALVES

WARNING
WARNING