FORSAIRE COUNTERFLOW DIRECT VENT GAS WALL HEATER
19
START-UP PROCEDURE
Start the furnace using the procedures in the section
“OPERATING YOUR FURNACE”.
WARNING:
Danger of bodily injury or death.
Liquefied petroleum gas (L.P. Gas) is heavier than
air and it will settle in any low area, including open
depressions and it will remain there unless the area is
ventilated. Never attempt to start-up the unit before
thoroughly ventilating area.
Check the furnace operation as outlined in the following
instructions. If any sparking, odors or unusual noises are
encountered, shut off electric power immediately. Recheck
for wiring errors or obstructions in or near fan motor.
CHECK GAS INPUT AND PRESSURES
For furnaces located at elevations between sea level and
2,000 feet, the measured input must not be greater than
the input shown on the rating plate of the furnace. For
elevations above 2,000 feet, the measured input must not
exceed the input on the rating plate reduced by 4 percent
for each 1,000 feet that the furnace is above sea level.
The gas supply pressure and manifold pressure with the
burners operating is specified on the rating plate.
Rated input will be obtained on a heating value of 2,500
BTU/hr. for propane at 10-inches manifold pressure with
factory-sized orifices. If L.P. Gas having a different heating
value is supplied, orifices must be changed by a qualified
service technician before the furnace is operated.
CHECK THERMOSTAT
Check thermostat operation. When set above room
temperature shown on the thermostat, the main burner
should light. Make certain the thermostat turns off the
furnace when the room temperature reaches the selected
setting and starts the furnace when room temperature
falls a few degrees.
ADJUST PILOT BURNER
(STANDING PILOT MODELS ONLY)
PiIot fIame should surround 5/8-inch to 1/2-inch of
the thermocouple tip. To adjust, remove the cap from
the pilot adjustment screw on gas valve. Turn screw
counterclockwise to increase the flame, clockwise to
decrease. Replace cap. Refer to
Page 25, Figure 30
.
CHECK THE MANIFOLD GAS PRESSURE
A tapped opening is provided in the gas valve to facilitate
measuring the manifold gas pressure. A “U Tube”
manometer having a scale range from 0 to 12-inches of
water should be used for this measurement. The manifold
pressure must be measured with the burner and pilot
operating. Any major changes in flow must be made by
changing the size of the burner orifice.
Check with your local gas supplier for proper orifice sizing.
CHECK THE GAS INPUT
(NATURAL GAS ONLY)
WARNING:
Natural gas heating value (Btu per
cubic foot) can vary significantly. Therefore, it is the
installer’s responsibility to see that Btu/hr. input to the
furnace is adjusted properly. Failure to do so could
cause combustion chamber failure, asphyxiation, fire or
explosion resulting in damage, bodily injury or death.
Refer to the National Fuel Gas Code (NFPA 54) to be
sure the furnace is burning fuel at the proper rate.
Under firing could cause inadequate heat, excessive
condensation or ignition problems. Over firing could
cause sooting, flame impingement or overheating of the
heat exchanger.
Before starting natural gas input check, obtain heating
value of gas (BTU per cubic foot) at standard conditions
from your local supplier. This factor is used in “Check the
Gas Input” section and procedure.
To measure the input, using the gas meter, proceed as follows:
1. Turn off gas supply to all other appliances except
the furnace.
2. With the furnace operating, time the smallest dial on
the meter for one complete revolution. If this is a
2-cubic-foot dial, divide the seconds by 2. If it is a
1-cubic-foot dial, use the time in seconds as is. This
gives the seconds per cubic foot of gas being delivered
to the furnace.
3. Assuming natural gas with a heating value of 1,000
BTUper cubic foot and 34-seconds per cubic foot used
as determined by step (2), then:
Seconds per hour = 3,600
Input = 1,000 x 3,600 / 34 = 106,000 Btu/hr.
This measured input must not be greater than the
input indicated on the nameplate of the furnace.
4. Relight all other appliances turned off in Step 1 above.
Be sure all pilots are operating.
FIGURE 27 - THERMOSTAT
INDICATOR LOWEST SETTIG
TYPE OF GAS
MANIFOLD PRESSURE, IN. W.C.
NATURAL
4.0
PROPANE
10.0
