AAON RL-240 - Manual (Page 33)

33
Gas Heating
Gas piping must be installed in accordance
with local codes, or in the absence of local
codes, installation must conform to the
current (United States) National Fuel Gas
Code ANSI-Z223.1/NFPA 54 or the current (Canada) National Fuel & Propane
Installation Code CSA B149.1 or B149.2.
Table 3 - Gas Piping Connections
Model
Option
B2
Quantity of
Heat
Exchangers
Connections
Quantity Size
1, 2, 3,
or 4
8 or less 1 2”
5 or 6 10 or 12 1 3”
Do not use gas piping smaller than unit gas
connections. Natural gas pipe runs longer
than 20 feet may require a larger supply pipe
than the unit connection size. Some utility
companies may also require pipe sizes larger
than the minimum sizes listed.
See unit nameplate for unit gas heating
capacities or the Unit Rating Sheet, which
can be obtained from the AAON sales
representative.
Table 4 - Natural Gas Maximum Piping Capacities (ft 3 /hr)
- Specific Gravity = 0.6, Supply Pressure ≤ 0.5 psi, Pressure Drop = 0.5” w.c.
Pipe Size
Length of Pipe
20 ft 50 ft. 100 ft. 150 ft. 200 ft.
2”
2785 1696 1165 936 801
2-1/2” 4437 2703 1857 1492 1277
3” 7843 4778 3284 2637 2257
3-1/2” 11484 6995 4808 3861 3304
4”
15998 9745 6698 5378 4603
Piping Sizing Example
A 100 ft pipe run is needed for a 1710 MBH
natural gas heater. The natural gas has a
rating of 1000 BTU/ft
3
and a specific gravity
of 0.6 (Obtain these values from the local
gas supplier.)
 
BTU
ft
MBH
1000
1710
3
1710 ft
3
/hr
From the natural gas maximum capacities
table, at 100 ft and 1710 ft
3
/hr the required
minimum pipe size is 2-1/2”.
Inlet and Manifold Pressures
For natural gas units, the minimum inlet gas
pressure to the unit is 6” w.c. and maximum
inlet gas pressure to the unit is 10.5” w.c.
For propane units, the minimum inlet gas
pressure to the unit is 11” w.c. and the
maximum inlet gas pressure to the unit is
13” w.c. A field provided 1/8” NPT pressure
tap is required to be installed in the piping
just upstream of the shutoff valve for test
gage connection to allow checking of the
gas supply pressure at the unit.
FOR YOUR SAFETY
Read the entire gas heating
installation section of this manual
before beginning installation of the
gas heating section.
If you do not follow these instructions
exactly, a fire or explosion may result
causing property damage, personal
injury or loss of life.
WARNING