Daikin IM 972-1 9
Mechanical Installation
Gas Supply, Condensate Drain
Gas Connection
IMPORTANT: Connect this unit only to gas supplied by a
commercial utility.
1 Install gas piping in accordance with local codes and
regulations of the local utility company. In the absence
of local codes, the installation must conform to the
specifications of the National Fuel Gas Code, ANSI
Z223.1 - latest edition.
Note: The use of flexible gas connectors is not permitted.
2
Connect the gas line to the gas valve supplied with unit.
Routing can be through the gas pipe opening shown in
Figure 7 or through the base as shown in Figure 13.
3 Size the gas line to the furnace adequate enough to
prevent undue pressure drop and never less than 1/2".
4 Install a drip leg or sediment trap in the gas supply line
as close to the unit as possible.
5 Install an outside ground joint union to connect the gas
supply to the control assembly at the burner tray.
6 Gas valves have been factory installed. Install a manual
gas valve where local codes specify a shut-off valve
outside the unit casing (see Figure 7).
Figure 7: Suggested Gas Piping
7
Make sure piping is tight. A pipe compound resistant
to the action of liquefied petroleum gases must be
used at all threaded pipe connections.
8 IMPORTANT: Any additions, changes or conversions
required for the furnace to satisfactorily meet the
application should be made by a qualified installer,
service agency or the gas supplier, using factory-
specified or approved parts. In the commonwealth of
Massachusetts, installation must be performed by a
licensed plumber or gas fitter for appropriate fuel.
IMPORTANT: Disconnect the furnace and its individual
shutoff valve from the gas supply piping during any pressure
testing of that system at test pressures in excess of 1/2 pound
per square inch gauge or isolate the system from the gas
supply piping system by closing its individual manual shutoff
valve during any pressure testing of this gas supply system at
pressures equal to or less than 1/2 PSIG.
IMPORTANT: Check the rating plate to make certain the unit
is equipped to burn the type of gas supplied. Care should be
taken after installation of this equipment that the gas control
valve not be subjected to high gas supply line pressure.In
making gas connections, avoid strains as they may cause noise
and damage the controls. A backup wrench is required to be
used on the valve to avoid damage.
The capacities of gas pipe of different diameters and lengths in
cu.ft. per hr. with pressure drop of 0.3 in. and specific gravity
of 0.60 (natural gas) are shown in Table 2.
After determining the pipe length, select the pipe size which
will provide the minimum cubic feet per hour required for the
gas input rating of the furnace. By formula:
The gas input of the furnace is marked on the furnace rating
plate. The heating v
alue of the gas (BTU/Ft
3
) may be
determined by consulting the local natural gas utility or the
LP gas supplier.
DANGER
Never test for gas leaks with an open flame. It can cause an
explosion or fire resulting in property damage, personal injury
or death. Use a commercially available soap solution made
specifically for the detection of leaks to check all connections
as specified in the “Mechanical Installation” section of these
instructions.
Table 2: Gas Pipe Capacity Table (Cu. Ft./Hr.)
Nominal
Iron Pipe
Size
Equivalent Length of Pipe, Feet
10 20 30 40 50 60 70 80
1/2” 132 92 73 63 56 50 46 43
3/4” 278 190 152 130 115 105 96 90
1” 520 350 285 245 215 195 180 170
1-1/4” 1,050 730 590 500 440 400 370 350
1-1/2” 1,600 1,100 890 760 670 610 560 530
Cu. Ft. per Hr. Required =
Gas Input of Furnace (BTU/Hr)
Heating Value of Gas (BTU/Ft
3
)
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