FloAire Indirect Fired Heater - Manual (Page 8)

8
Gas Pressure Table
Gas Pressure Type Gas Pressure
Inlet Pressure - Natural Gas 7 in. w.c. – 14 in. w.c.
Inlet Pressure - Propane 11 in. w.c. – 14 in. w.c.
Max. Manifold Pressure - Natural Gas 3.5 in. w.c. maximum
Max. Manifold Pressure - Propane 10 in. w.c. maximum
Min. Manifold Pressure - Natural Gas 0.56 in. w.c. maximum
Min. Manifold Pressure - Propane 1.6 in. w.c. maximum
Gas Connection Sizes
Unit Size Gas Pipe Size (NPT)
Size 1 ¾”
Size 2 1”
Size 3 1”
Gas Connection Diagram
Gas
Installation of gas piping must conform with local building codes, or in the absence of local codes, with 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 14 IN. W.C. SEE UNIT
RATING PLATE 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 with 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 the table to the right. Avoid
multiple taps in the gas supply so the unit has a steady
supply of gas at all times.
4. Install a ground joint union with brass seat and a
manual shut-off valve external to the unit casing, as
shown below, adjacent to the unit for emergency shut-off and easy servicing of controls.
5. Provide a sediment trap, as shown below, before each unit and where low spots in the pipe line
cannot be avoided.
6. Blow out the gas line to remove debris before making connections. Purge line to remove air
before attempting to start unit. Purging of air from gas lines should be performed as described in
ANSI Z223.1-latest edition “National Fuel Gas Code”, or in Canada in CAN/CGA-B149.
7. All field gas piping must be pressure/leak tested prior to 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 ½ psi. The
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 ½ psi. This must be performed
on an annual basis.
8. This unit requires a constant 7 in. w.c. minimum natural gas supply, (LP should be 11 in. w.c.
minimum) when the unit is operating at maximum gas flow. If the gas supply exceeds 14 in.
w.c. it will damage the internal valve components, and if it is below 7 in. w.c., the heater may not
perform to specifications.
NOTICE
Refer to the heater rating
plate for determining the
minimum
gas supply
pressure for obtaining the
maximum gas capacity for
which this heater is specified.