5
Part 1 Installation
VI - Piping
CAUTION: The available gas pressure should be
within the limits shown in the SPECIFICATIONS
section. Excessive pressure will damage the
Combination Gas Valve and Regulator. If the supply
pressure exceeds the 14.0" W.C. maximum, a suitable
intermediate main regulator must be installed ahead of
the Main Manual Shut-Off Valve shown in Figure 6.
The burner gas supply piping should branch off from the
main line as close to the gas meter as possible. Do not con-
nect to the bottom of a horizontal section. Use new black pipe
and malleable fittings free of burrs.
Provide a sediment trap, union and 1/8" pressure tap in
piping close to burner as shown in Figure 6.
Use pipe joint compound approved for use with natural and
liquid petroleum gases.
Piping must comply with local codes.
To obtain the maximum firing rate of the burner, the fuel
gas supply piping must be sized to provide a minimum of 6" w.c.
pressure to the inlet of the combination valve when the burner
and all other gas appliances are on.
When pressure testing the supply piping, the burner valve train
must be protected.
CAUTION: If the test pressure is 0.5 PSIG or less, closing
the Main Manual Shut-Off Valve will suffice.
DANGER: Explosion hazard.
Do not use oxygen for pressure testing. An
explosion could occur during initial start-up.
Figure 5: Wiring Diagram
Figure 6: Piping Connections
Midco International Inc. - Chicago IL - www.midcointernational.com
Capacities shown are for a total pressure drop of 0.3"W.C.
For 0.5"W.C. pressure drop, multiply capacity shown by 1.3.
Propane capacities shown are for a total pressure drop of
0.5” W.C. For higher permissible pressure drops, consult
your gas supplier.
Table 2: Schedule 40 NPT
Pipe-Capacity Chart
10
200
590
400
1075
900
40
275
200
500
450
1040
650
75
190
150
360
325
750
475
20
150
400
275
730
600
900
Pipe
Size
3/4
3/4
1
1
1 1/4
1 1/4
1 1/2
1 1/2
Natural
Propane
Natural
Propane
Natural
Propane
Natural
Propane
100
160
300
275
630
400
975
Approximate Capacity -MBH
Pipe Length
Type
of Gas
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