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IM 970-2 • MAVERICK I ROOFTOP 8
www.DaikinApplied.com
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Gas Supply, Condensate Drain and Piping
Gas Connection
WARNING
Connect this unit only to gas supplied by a commercial utility.
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.
CAUTION
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.
CAUTION
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.
NOTICE
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.
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.
2. Connect the gas line to the gas pipe inlet opening
provided into the ½" inlet valve. See
Figure 1 on page
5
or
Figure 4 on page 6
for typical piping.
3. Size the gas line to the furnace adequate enough to
prevent undue pressure drop and never less than ½".
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 8
).
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.
NOTE:
The use of flexible gas connectors is not permitted.
The Commonwealth of Massachusetts requires the
gas shut-off valve to be a T-handle gas lock.
Figure 8: Suggested Gas Piping
Table 3: Gas Pipe Capacity Table (Cu. Ft./Hr.)
Nominal
Iron Pipe
Equivalent Length of Pipe, Feet
Size
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
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 3
.
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:
Gas Input of Furnace
(BTU/Hr.)
Cu. Ft. Per Hr. Required = _________________
Heating Value of Gas
(BTU/Ft.)
The gas input of the furnace is marked on the furnace
rating plate. The heating value of the gas (BTU/FT
3
) may be
determined by consulting the local natural gas utility or the L.P.
gas supplier.