Gas Supply And Gas Pipe Sizing; General; Gas Connections - A.O. Smith 910 Installation Manual And Owner's Manual

Do not use this water heater with any gas other than the one listed on the rating
plate.
Ensure that any and all gas regulators used are operating properly and providing gas
pressures within the specified range shown below. Excess gas inlet pressure may
cause serious accidents.
WARNING
Conversion of this unit from natural gas to propane or vice versa will void all
warranty. Contact your local distributor to get the correct unit for your gas type. The
manufacturer is not liable for any property and/or personal damage resulting from
gas conversions.
Failure to observe these warnings could result in severe personal injury, carbon
monoxide poisoning, or death.
Minimum and maximum inlet gas pressures:
Gas type
Natural Gas
Propane
Inlet gas pressures that fall outside the range of values listed above may adversely affect the
performance of the water heater. These pressures are measured when the water heater is in full
operation and when it is in stanby.
Inlet gas pressure must not exceed the above maximum values; gas pressure above the specified range
will cause dangerous operating conditions and damage to the unit.
Until testing of the main gas line supply pressure is completed, ensure the gas line to the water heater
is disconnected to avoid any damage to the water heater.
If the gas supply pressure to the heater is greater than the specified maximum, a field-supplied
regulator is required. The regulator must lower the gas pressure within the approved range.
Install the gas regulator according to the manufacturer's instructions.
The regulator must be sized for the water heater input and provide the specified pressures that
are listed on the rating plate.
In the absence of minimum install distance, it is recommended that the gas regulator be installed
no closer than 3 ft (1 m) from the water heater's inlet gas connection.
1. Install a full port, manual gas shutoff valve between the water heater and the gas supply line.
2. When the gas connections are completed, perform a gas leak test either by applying soapy water to all
gas fittings and observing for bubbles or by using a gas leak detection device.
The water heater and its individual shutoff valve must be disconnected from the gas supply
piping system during any pressure testing of that system at test pressures in excess of 1/2 psi
(3.5 kPa).
The water heater must be isolated from the gas supply piping system by closing its individual
manual shutoff valve during any pressure testing of the gas supply piping system at test
pressures equal to or less than 1/2 psi (3.5 kPa).
3. Always purge the gas line of any inert gas, debris, and/or water before connecting to the gas inlet.
Size the gas pipe to supply the necessary volume of gas for the water heater. Refer
NOTICE
to and follow the requirements listed in the current edition of ANSI Z223.1/NFPA
54 (USA), B149.1 (Canada), or local codes. Otherwise, flow capabilities and output
temperatures will be limited.

-General-

Inlet gas pressure
Min. 4.0" W.C. (1.00 kPa) – Max. 10.5" W.C. (2.61 kPa)
Min. 8.0" W.C. (1.99 kPa) – Max. 14.0" W.C. (3.48 kPa)
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