PG80MSU: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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Adjust Temperature Rise
6. Set temperature rise. The furnace must operate within the
temperature rise ranges specified on the furnace rating plate. Do not
exceed temperature rise range specified on unit rating plate.
Determine the temperature rise as follows:
NOTE:
Blower access door must be installed when taking temperature
rise reading. Leaving blower access door off will result in incorrect
temperature measurements.
a. Place thermometers in return and supply ducts as close to furnace
as possible. Be sure thermometers do not see radiant heat from
heat exchangers. Radiant heat affects temperature rise readings.
This practice is particularly important with straight-run ducts.
b. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine air
temperature rise.
NOTE:
If the temperature rise is outside this range, first check:
(1.)Gas input for heating operation.
(2.)Return and supply ducts for excessive restrictions causing
static pressures greater than the maximum heating static listed on
the rating plate.
c. Adjust air temperature rise by adjusting blower speed. Increase
blower speed to reduce temperature rise. Decrease blower speed
to increase temperature rise
d. Turn thermostat down below room temperature and remove
blower access door.
e. Refer to the
FURNACE CONTROL PROGRAMMING AND
NAVIGATION
section of this manual for instructions on
adjusting the blower speed.
f. Repeat steps a through e until temperature rise is within range on
rating plate.
g. When correct input rate and temperature rise is achieved, turn
gas valve ON/OFF switch to OFF.
h. Remove manometer or similar device from gas valve.
i. Tighten set screw on outlet tower pressure tap with 3/32 in. hex
wrench.
Check Safety Controls
1. Check Main Limit Switch(es)
This control shuts off combustion control system and energizes
air-circulating blower motor, if furnace overheats. By using this
method to check limit control, it can be established that limit is
functioning properly and will operate if there is a restricted duct
system or motor failure. If limit control does not function during
this test, cause must be determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of cardboard or sheet
metal until the limit trips.
c. Unblock return air to permit normal circulation for 5 minutes.
d. Reset unit power to clear limit fault lockout.
2. Check draft safeguard switch.
The purpose of this control is to cause the safe shutdown of the
furnace during certain blocked vent conditions.
a. Verify vent pipe is cool to the touch.
b. Disconnect power to furnace and remove vent connector from
furnace vent elbow.
c. Restore power to furnace and set room thermostat above room
temperature.
d. After normal start-up, allow furnace to operate for 2 minutes,
then block vent elbow in furnace 80 percent of vent area with a
piece of flat sheet metal.
e. Furnace should cycle off within 2 minutes. If gas does not shut
off within 2 minutes, determine reason draft safeguard switch did
not function properly and correct condition.
f. Remove blockage from furnace vent elbow.
g. Switch will auto-reset when it cools.
h. Re-install vent connector.
i. Reset unit power to clear limit fault lockout.
Checklist
• Put away tools and instruments. Clean up debris.
• Check Input/Output gas pressure
• Check heat rise per application static pressure
• Cooling CFM per application static pressure
• Verify that blower-OFF delay time is selected as desired.
• Verify that blower and burner access doors are properly installed.
• Cycle test furnace with room thermostat.
• Check operation of accessories per manufacturer’s instructions.
• Review User’s Guide with owner.
• Attach literature packet to furnace.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in:
-
Overheating the heat exchangers or condensing flue gases in
heat exchanger areas not designed for condensate.
-
Shortened furnace life
-
Component damage.
Temperature rise must be within limits specified on furnace rating plate.
Recommended operation is at midpoint of rise range or slightly above.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Gas valve outlet pressure tap must be tightened to prevent gas leak.
CAUTION
!
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in reduced furnace life.
Recheck temperature rise. It must be within limits specified on the
rating plate. Recommended operation is at the mid-point of rise range
or slightly above.
