PAGE 34of 46 HG-1-1701 GAS-FIRED HEATER
LAST UPDATED: JAN-25-2022 © SAMUEL JACKSON, INCORPORATED 2011 ALL RIGHTS RESERVED
GAS PIPING
The size of the pipe supplying gas to heaters and other appliances should be large enough
to prevent excessive pressure losses when all of them are in use. See following Table of
RECOMMENDED
MINIMUM PIPE SIZES
(Drawing 14-1899) for heater capacities,
pipe lengths, and pressures.
Where LPG (Liquefied Petroleum Gas, Propane, Butane) is used as fuel, see the
following Drawing 14-3566
LIQUEFIED PETROLEUM GAS TANK INSTALLATION
FOR HUMIDAIRE UNITS AND DRYING HEATERS
for recommended practices.
Emergency shut-off valves should be provided to permit turning off the fuel in an
emergency. They should be located so that they are accessible in an emergency situation.
IRI (Industrial Risk Insurers) and some state and local authorities require venting the gas
regulator and normally open vent valve.
NFPA (National Fire Protection Association) 86* states:
3-3.4.3.2 Regulators shall be vented to a safe location, where vented gas cannot
re-enter the building without extreme dilution. The terminating end shall be
protected against water entry and bug-screened. Vent pipe shall be of adequate
size so as to not lengthen response time.
3-3.4.3.3 Vent lines from multiple regulators, where manifolded together, shall be
piped in such a manner that diaphragm rupture of one will not backload the
others.
3-3.4.3.4 Vents from gas pressure switches, but from no other devices, may be
vented into the regulator lines provided that switch or regulator diaphragm failure
will not backload the regulator.
* Reprinted with permission from NFPA 86-1985, Standard for Ovens
and Furnaces, copyright © 1985, National Fire Protection Association,
Quincy, Mass. 02269. This reprint of material is not the complete and
official position of the NFPA on the referenced subject which is
represented only by the standard in its entirety.
Note: The HG-1-1701 is usually at the end of the gas line and therefore will be the first
device to have gas pressure issues in cold weather when all gas burners are running at
maximum. We recommend that a gas gauge be installed on the high-pressure side
(before the regulator) where it can be easily seen. If the burner is installed adjacent to a
Humidaire, the gauge can be used as an indicator for both.
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