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15
REGULATOR
COVER SCREW
ADJUSTMENT
SCREW
REGULATOR SPRING
(PROPANE - WHITE)
NATURAL - SILVER)
GAS PRESSURE
REGULATOR
ADJUSTMENT
MANIFOLD
PRESSURE TAP
INLET
PRESSURE TAP
ON/OFF SWITCH
PLASTIC
(
A07751
Fig. 13 -- Single--Stage Gas Valve
If larger adjustments are required, change main burner orifices
following the recommendations of national and local codes.
NOTE: All other appliances that use the same meter must be
turned off when gas flow is measured at the meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (See Fig. 11) and connect
manometer. Turn on gas supply to unit.
3. Record number of seconds for gas meter test dial to make
one revolution.
4. Divide number of seconds in Step 3 into 3600 (number of
seconds in one hr).
5. Multiply result of Step 4 by the nu mber of cubi c f eet (cu ft)
shown for one revolution of test dial to obtain cubic feet (cu
ft) of gas flow per hour.
6. Multiply result of Step 5 by Btu heating valu e of gas to
obtain total measured input in Btuh. Compare this value
with heating input shown in Table 3 (Consult the local gas
supplier if the heating value of gas is not known).
EXAMPLE: Assume that the size of test dial is 1 cu ft, one
revolution takes 32 sec, and the heating value of the gas is 1050
Btu/ft
3
. Proceed as follows:
1. 32 sec. to complete one revolution.
2. 3600 ÷ 32 = 112.5.
3.112.5x1=112.5ft
3
of gas flow/hr.
4. 112.5 x 1050 = 118,125 Btuh input.
If the desired gas input is 115,000 Btuh, only a minor change in the
manifold pressure is required.
Observe manifold pressure and proceed as follows to adjust gas
input:
1. Remove regulator cover screw over plastic adjustment
screw on gas valve (See Fig. 13).
2. Turn plastic adjustment screw clockwise to increase gas
input, or turn plastic adjustment screw counterclockwise to
decrease input (See Fig. 13). Manifold pressure must be
between 3.2 and 3.8 IN. W.C.
FIRE AND UNIT DAMAGE HAZARD
Failure to follow this warning could result in personal
injury or death and/or property damage.
Unsafe operation of the unit may result if manifold pressure
is outside this range.
!
WARNING
3. Replace regulator cover screw on gas valve (See Fig. 13).
4. Turn off gas supply to unit. Remove manometer from
pressure tap and replace pipe plug on gas valve. (See Fig.
11.) Turn on gas to unit and check for leaks.
Measure Manifold Pressure (Propane Units)
Refer to propane kit installation instructions for properly checking
gas input.
NOTE: For installations below 2,000 ft (610 m), refer to the unit
rating plate for proper propane conversion kit. For installations
above 2,000 ft (610 m), contact your distributor for proper propane
conversion kit.
Check Burner Flame
With control access panel (see Fig. 19) removed, observe the uni t
heating operation. Watch the burner flames to see if they are light
blue and soft in appearance, and that the flames are appr oximately
the same for each burner. Pr opane will have bl ue flame (See Fig.
12) . Refer to the Maintenance section for information on burne r
removal.
Norma l Operation
An LED (light--emitting diode) indicator is prov ided on the
integrated gas unit controller (IGC) to monitor operation. The IGC
is located by removing the cont rol access panel (see Fig. 19) .
During normal operation, the LED is continuously on (See Table 5
for error cod es).
Airflow and Temperature Rise
The heating section for each size unit i s designed and approved for
heating operation within the temperature--rise range stamped on the
uni t rating plate.
Table 10 show s the approved tempe rature rise range for each
heating input, and the air delivery cfm at various temperature rises
for a given external static pressure. The heating operation airflow
must produce a temperature rise that falls within the approved
range.
Refer to Indoor Airflow and Airflow Adjustments section to adjust
heating airflow when required.
Limit Switches
Normally closed limit switch (LS) completes the control c ircuit.
Should the leaving--air temperature rise above the maximum
allowable temperature, the limit switch opens and the control
circuit “breaks.” Any interruption in the control circuit instantly
closes the gas valve and stops gas flow to the burners and pilot.
The blower motor continues to run until LS resets.
When the air temperature at the limit switch drops to the
low--temperature setting of the limit switch, the switch closes and
677C-- --A