Installation guide
5, Divide number of seconds in step 4 into 3600 (number
of seconds in 1 hour).
6. Multiply result of step 5 by the number of cubic feet
shown for one revolution of the meter dial to obtain the
cubic feet of gas flow per hour.
7,
Multiply result of step 6 by Btu heating value of gas to
obtain total measured input in Btu/hr. Compare this
with the unit rating plate and make any adjustments
as needed according to the "Manifold Pressure
Adjustments" section. Consult with local gas supplier
if the heating value of gas is not known.
NOTE: From the time the thermostat is set to gas heat, you
have 10 minutes to complete low stage gas adjustments.
After 10 minutes, the thermostat will shift to high stage gas
heat.
8. Turn thermostat mode to OFF. Reset the thermostat
by changing mode back to HEAT and adjust
temperature set point to 5 degrees above room
temperature to set unit to low stage.
9. Repeat steps 4 thru 7 for low stage.
10. Return thermostat to customer's desired settings
(balance point temperature, mode, and desired
temperature) after final checkout.
11. Relight all appliances and ensure all pilots are
operating.
Example: Assume that the size of the meter dial is 1 cu. ft.,
one revolution takes 44 seconds, and the heating value of
the gas is 1020 Btu/ft3. Proceed as follows:
1.38 sec. To complete 1 revolution
2. 3600/38 = 94.7
3.94.7 x 1 = 94.7
4.94.7 x 1020 = 96,632 Btu/hr
For this example, the nameplate input is 100,000 Btu!hr, so
only a minor change in manifold pressure is required. In no
case should the final manifold pressure vary more than
+- .3 in wc from the values in Tables 1 and 2.
GAS HEATING TEMPERATURE RISE CHECK
NOTE: Air temperature rise is the temperature difference
between supply and return air. With a properly designed
distribution system, the proper amount of temperature rise
will normally be obtained when the unit is operating at rated
input with the recommended blower speed.
1. The temperature rise must be within the specifica-
tions marked on the unit rating plate for each stage of
gas heat.
To check the temperature rise through the unit, place
thermometers in the supply and return air ducts as
close to the unit as possible.
be necessary to change the blower speed. A faster blower
speed will decrease the temperature rise. A slower blower
speed will increase the temperature rise.
NOTE: The blower speed MUST be set to give the correct
air temperature rise through the furnace as marked on the
rating plate. See Figure 13 for more information.
2. After 15 minutes of operation check the limit control
function by blocking the
return air grille(s).
After several minutes the main burners and pilot should
go OFE The circulating air blower should continue to
run.
3,
Remove air restrictions. Pilot and main burners should
relight after a cool down period of a few minutes.
Adjust the thermostat setting below room temperature.
Main burners and combustion air blower should go
OFF.
The circulating air blower should continue to run for 60,
100, 140 or 180 seconds. This time is adjustable. See
Figure 16 for more information.
4. Set thermostat Heat-Cool selector to OFF.
FAN CONTROL CHECK
Figure 16 Fan Delay DIP Switch Settings
80 J :_ยข/
J
(;t ,[/ L_,l
The Fan Control has adjustable settings for the circulating
air blower to delay it "ON" and "OFF".
1. The Fan Control has a fixed "ON" delay of 30 seconds,
and a field adjustable "OFF" delay of 60, 100, 140 and
180 seconds. The "OFF" delay is factory set at 140
seconds.
Refer to Figure 16 for proper DIP switch settings.
2. Operate the furnace and ensure that the blower turns
ON and OFF at the appropriate time to provide the
desired comfort level.
10. OPERATION
ELECTRICAL SHOCK HAZARD.
Failure to follow this warning could result in personal
injury or death.
Turn off electric power supply at disconnect switch or
service panel before removing any access or service
panel from unit.
Open ALL registers and duct dampers. Operate unit
AT LEAST 15 minutes before taking readings.
If the correct amount of temperature rise is not obtained
when operating on the recommended blower speed, it may
b2J
TROUBLE SHOOTING
Models are factory equipped with the Comfort AlertTM
Diagnostics device (refer to Figure 17) in the control box.
Comfort Alert TM Diagnostics device provides compressor
staging from low to high and high to low capacity. Comfort