13
WARNING
NEVER USE AN OPEN FLAME TO CHECK FOR GAS LEAKS. THIS PRACTICE MAY
CAUSE A FIRE, EXPLOSION, BODILY HARM INCLUDING DEATH OR PROPERTY
DAMAGE.
Pipe joint compound must be resistant to the action of L.P. gas.
A union and listed manual shutoff must be installed exterior to the heater cabinet so the control
assembly may be easily removed.
A plug on the supply pipe at the manual valve for the purpose of making pressure measure-
ment must also be installed. The valve should be readily accessible for turning on or off. A
capped sediment trap, sometimes referred to as a drip leg, should be installed in the gas sup-
ply pipe as close to the heater as possible. This trap must incorporate a change of direction of
the gas flow.
Refer to local codes or other available publications for proper location of the manual shutoff
and sediment trap lengths.
The gas pipe must be sized to eliminate undue pressure drop. See pipe capacity table or con-
sult your local utility.
Both the supply and manifold pressure must be measured and adjusted, if necessary.
NOTE: Copper tubing must not be used for natural gas installations where more than .3 grains
of hydrogen sulfide per 2.83 standard cubic meters of gas is present.
Capacity of gas pipe of different diameters and length in M
3
/HR with a pressure drop of 1.24
Mbar and a specific gravity of 0.60 (natural gas).
PIPE
LENGTH OF PIPE IN METERS
SIZE*
3 6 9 12 15 18 21 24
1/2 4.29 3.40 2.74 2.32 2.06 1.87 1.72 1.61
3/4 10.20 7.08 5.66 4.81 4.27 3.91 3.54 3.34
1
19.27 13.17 10.62 9.06 8.07 7.36 6.80 6.23
1
1/4 39.67 26.92 21.82 18.70 16.43 15.02 13.88 13.03
1
1/2 59.51 41.37 33.43 28.05 25.50 22.95 21.25 19.55
* Nominal size of Iron Pipe in inches.
After the length of pipe has been determined, select the pipe size, which will provide the mini-
mum gas flow for the required input of the appliance. In the case where more than one appli-
ance utilizes the same supply pipe be sure to consider the sum of all appliances.
Gas pipe must not run through or inside circulating air ducts.
Do not use piping of a smaller size than the gas valve inlet size.
The gas input of the appliance is marked on the specification plate. The heating value of the
gas may be determined by contacting the gas utility or gas supplier.
CIRCULATING AIR SUPPLY AND RETURN AIR
The circulating air supply may be taken from; 1) outside the building, 2) return ducts from sev-
eral rooms, 3) central return, 4) any combination of the above.
It is recommended that the supply duct have an access panel so the heat exchanger can be
viewed. This panel shall be of sufficient size to permit the entrance of a light or probe to assist
in the observation of the heat exchanger integrity or sampling the air stream. It should sealed
to prevent air leakage during normal operation.
Summary of Contents for GMP Series
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