Element
Section 6: Gas Supply and Piping
L-OMM-0003_A
• 10/8/2021 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page
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GAS SUPPLY AND PIPING
Verify the type of gas specified on rating plate is supplied to the unit. This unit is designed for
operation up to 2000 feet altitude. Appliance Btu/h input derates 4% per 1000 feet elevation
above sea level. Consult Factory for installations above 2000 feet elevation.
6.1 Inlet Pressure
Measure at the inlet pressure tap located at the main gas cock. The inlet pressure must remain
within the minimum and maximum values while the unit is at rest and while the unit is operating at
maximum firing rate.
Inlet Pressure
Nat. Gas
Propane
Maximum Static Pressure (in-H
2
O)
14.0
13.0
Minimum Flow Pressure (in-H
2
O)
3.5
8.0
6.2 Manifold Pressure
Measure at the pressure tap on the downstream side of the manual valve closest to the burner.
The rated manifold pressure appears on the product data label near the front of the appliance.
6.3 Gas Connection
1. Safe operation of the unit requires adequate gas supply with the required static and dynamic
(flow) pressures. Actual piping selection depends on many variables that must be carefully
considered by the gas piping system designer.
2. Do not select gas pipe sizes based only on the supplied tables. These tables are for use by the
gas piping system designer as a reference in checking pipe size selections.
3. Gas pipe size may be larger than heater connection.
4. Installation of a union is suggested for ease of service.
5. Install a manual main gas shutoff valve on the gas supply piping connected to the appliance to
isolate the burner and gas train from the main supply gas in compliance with NFPA 54 National
Fuel Gas Code and most local Codes.
6. The gas system installer must clearly identify the emergency shut-off device.
7. A sediment trap (drip leg) MUST be provided in the inlet of the gas connection to the unit.
8. The combination gas valve incorporates an internal vent limiter. Venting to outdoors is not
allowed.
