A.O. Smith BTH 120 - 250 - Manual (Page 13)

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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.
FIGURE 15
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. GAS SUPPLY LINE MUST BE CAPPED WHEN
DISCONNECTED FROM THE HEATER. FOR TEST PRESSURES OF 1/2 PSIG
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.
CAUTION
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.
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" W.C. and a minimum as shown in Table 4: that is, for Natural Gas, 5.0"
W.C. for BTH 120 & 250 or 4.5" W.C. for BTH 150 & 199 or; for L.P. Gas,
11.0" W.C. The inlet gas pressure must not exceed the maximum value. A
service regulator should be installed within ten feet (10') of unit.
GAS VALVES
WARNING
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. A.G.A. 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
Your local code authority may have other specific relief valve requirements.
WARNING
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.