Specifications

GF-2030 Benchmark Series Boilers
TAG-0047_0G Gas Supply Design Guide
PR1 10/04/13 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, New York 10913 • Phone: [phone] Page 6 of 10
GAS PIPING
All gas piping and components must comply with NFPA local codes, and utility requirements minimum. Only gas
approved fittings, valves, or pipe should be utilized.
Standard industry practice for gas piping is Schedule 40 iron pipe and fittings. All high and low gas pressure piping
systems must comply with local utility and building codes.
Assembled piping should be clean of all debris, pipe chips, or foreign material to prevent any from entering the
Innovation Low NOx series boiler gas train. Piping should be tested as prescribed in NFPA 54. Equipment should be
isolated before testing any piping system over the allowable pressure. DO NOT EXCEED 14.0” W.C. on the inlet side
of the Benchmark boiler at any time for BMK 750 through BMK 3000 Models. For BMK 6000 boilers, DO NOT
EXCEED 2.0 P.S.I. on the inlet side of the boiler at any time.
GAS SUPPLY MAIN SIZING
Gas pipe sizing, for either a single or multiple boiler installation, shall be sized for a maximum pressure drop of 0.3”
W.C., from the source to the final boiler. The maximum gas flow rate required is the sum of the maximum inputs of
each unit divided by the heat of combustion of the fuel supplied at the location, (approximately 1,030 BTU per cubic foot
for natural gas or 2,520 BTU per cubic foot for propane gas). The fuel supplier or utility should be consulted to confirm
that sufficient volume and normal pressure is provided to the building at the discharge side of the gas meter or supply
pipe. For existing installations with gas equipment, gas pressure should be measured with a manometer to be certain
sufficient pressure is available. Before sizing gas piping, a survey of all connected gas devices should be made. Gas
piping supplying more than one gas device must be able to handle the total connected input within the allowable gas
pressure drop. The allowable minimum and maximum gas pressure for each device should be considered. Whenever
the minimum and maximum gas pressures vary between devices, gas pressure regulators at each unit should be
installed to allow regulation at any individual unit. Gas pressure must never exceed the maximum allowable rating of
any connected device.
The total length of gas piping as well as fitting pressure drop must be considered when sizing the gas piping. Total
equivalent length should be calculated from the meter or source location to the last boiler connected on the header.
The Gas Piping Tables 1, 2 and 3 (see below) containing data extracted from NFPA 54 should be used as a minimum
guideline. Gas pipe size should be selected on the total equivalent length from the appropriate pressure table. The gas
volume for cfh flow will be the input divided by the calorific value of the fuel to be supplied.
GAS HEADER SIZING
Main supply gas pipe sizing should be developed for the total plant. Boiler gas manifold piping should be sized based
on the volume requirements and lengths between boilers and the fuel main. Multiple boiler manifold sizing (Diagram 2)
indicates the proper sizing for units placed on the factory standard 52” centers with 2” takeoffs for each unit. Header
sizes can be either full size or stepped in size as units are connected. A typical gas piping header diagram for a 3-
Module Benchmark Boiler Plant is illustrated in Diagram 3.
BENCHMARK SERIES GAS HEADER SIZING
No. of Boilers 1 2 3 4 5 6 7 8
Sch. 40 Iron Pipe 2” 4” 4” 4” 5” 5” 6” 6”
Diagram 2. Multiple Boiler Manifold Chart *
* Depending on gas piping layout. See Gas Piping Tables 1 – 4, below.