9
Gas
Installation of gas piping must conform with local building codes, or in the absence of local codes to the
National Fuel Gas Code, ANSI Z223.1 (NFPA 54) – latest edition. In Canada, installation must be in
accordance with CAN/CGA-B149.1 for natural gas units and CAN/CGA-B149.2 for propane units.
WARNING: INLET GAS PRESSURE MUST NOT EXCEED PRESSURE INDICATED ON NAMEPLATE.
SEE UNIT NAMEPLATE FOR PROPER GAS SUPPLY PRESSURE AND GAS TYPE.
1. Always disconnect power before working on or near a heater. Lock and tag the disconnect switch or
breaker to prevent accidental power-up.
2. Piping to the unit should conform to local and national requirements for type and volume of gas
handled, and pressure drop allowed in the line. Refer to the Gas Engineer’s Handbook for gas line
capacities.
3. The incoming pipe near the heater should be sized to match the connection on the outside of the unit.
Unit inlet sizes are shown in Table 2. The unit requires a steady supply of gas at all times, avoid
multiple taps in the gas supply line.
4. Install a ground joint union with brass seat and a manual shut-off valve external to the unit casing.
Install shut-off valve adjacent to the unit for emergency shut-off and easy servicing of controls. Refer to
Figure 5.
5. Provide a sediment trap, as shown in Figure 5, before each unit and where low spots in the pipeline
cannot be avoided.
6. Clean out the gas line to remove debris before making connections. Purge gas line to remove air
before attempting to start unit. Purging air from gas lines should be performed as described in ANSI
Z223.1-latest edition “National Fuel Gas Code,” or in Canada as described in CAN/CGA-B149.
7. All field gas piping must be pressure/leak tested before unit operation. Use a non-corrosive bubble
forming solution or equivalent for leak testing. The heater and its individual shut-off 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.
8. This unit requires the gas pressure to be within the unit’s minimum and maximum gas pressure
ratings. If the pressure is greater than the maximum, the internal valve components will be damaged. If
the pressure is below the minimum, the heater will not perform to specifications. Refer to Table 3 on
page 10.
Table 2 - Gas Connection Sizes
Unit Size Gas Pipe Size (NPT)
76 1/2”
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