Energy Tech Laboratories Modular Direct Fired Heaters Gas Connection Sizes, Gas Pressure Table

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 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 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		Gas Connection Sizes
	match the connection on the outside of the unit. Unit inlet
	sizes are shown in the table to the right. Avoid multiple		Unit Size	Gas Pipe Size (NPT)
	taps in the gas supply so the unit has a steady supply of		Size 1	¾”
	gas at all times.		Size 2	1”
4.	Install a ground joint union with brass seat and a manual
			Size 3	1”
	shut-off valve external to the unit casing, as shown below,
			Size 4	1-1/4”
	adjacent to the unit for emergency shut-off and easy
			Size 5	1-1/2”
	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	Gas Pressure Table
	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

Gas Pressure Type	Gas Pressure
Size 1-3 Inlet Pressure	7 in. w.c. – 14 in. w.c.
Size 4-5 Inlet Pressure	7 in. w.c. – 5 psi.
Max. Manifold Pressure - Natural Gas	5 in. w.c. maximum
Max. Manifold Pressure - Propane	2.5 in. w.c. maximum

individual manual shutoff valve

during any pressure testing of the gas supply piping system at test pressures equal to or less than ½ psi.

8. This unit requires a constant 7 in. w.c. minimum natural gas supply, when the unit is operating at maximum gas flow. If the gas supply exceeds 14 in. w.c. (5 psi. for sizes 4-5 housings) 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.

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