PG80VTLA: 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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(out) to decrease input rate or clockwise (in) to increase input
rate.
NOTE: DO NOT set low-heat manifold pressure less than 1.4-In. W.C.
or more than 1.7-In. W.C. for natural gas. If manifold pressure is outside
this range, change main burner orifices.
i. Install low-heat regulator adjustment cap.
j. Move setup switch SW1-2 to off position after completing
low-heat adjustment.
k. Leave manometer or similar device connected and proceed to
Step 4.
4. Adjust manifold pressure to obtain high fire input rate. (See
Fig. 21)
a. Jumper R to W/W1 and W2 thermostat connections on furnace
control. This keeps furnace locked in high-heat operation.
b. Remove regulator adjustment cap from high-heat gas valve
pressure regulator (see Fig. 21) and turn high heat adjusting
screw (3/16-in. or smaller flat-tipped screwdriver)
counterclockwise (out) to decrease input rate or clockwise (in) to
increase input rate.
NOTE: DO NOT set high-heat manifold pressure less than 3.2-In. W.C.
or more than 3.8 In. W.C. for natural gas. If manifold pressure is outside
this range, change main burner orifices to obtain manifold pressure in
this range.
c. When correct input is obtained, replace caps that conceal gas
valve regulator adjustment screws. Main burner flame should be
clear blue, almost transparent.
d. Remove jumpers R to W/W1 and R to W2.
5. Verify natural gas input rate by clocking meter.
NOTE: Gas valve regulator adjustment caps must be in place for proper
input to be clocked.
a. Turn off all other gas appliances and pilots served by the meter.
b. Move setup switch SW1-2 to ON position. This keeps furnace
locked in low-heat operation.
c. Jumper R to W/W1.
d. Run furnace for 3 minutes in low-heat operation.
e. Measure time (in sec) for gas meter to complete 1 revolution and
note reading. The 2 or 5 cubic feet dial provides a more accurate
measurement of gas flow.
f. Refer to Table 11 for cubic ft. of gas per hr.
g. Multiply gas rate cu ft./hr by heating value (Btuh/cu ft.) to obtain
input. If clocked rate does not match required input from Step 1,
increase manifold pressure to increase input or decrease manifold
pressure to decrease input. Repeat steps b through e until correct
low-heat input is achieved. Re-install low heat regulator seal cap
on gas valve.
h. Move setup switch SW1-2 to OFF position and jumper R to
W/W1, and W2. This keeps furnace locked in high-heat
operation. Repeat items d through g for high-heat operation.
6. Set Temperature Rise
NOTE: Blower access door must be installed when taking temperature
rise reading. Leaving blower access door off will result in incorrect
temperature measurements.
When setup switch SW1-4 is ON, operation will be near the high end of
the rise range for improved comfort.
Furnace must operate within ranges of temperature rise specified on the
furnace rating plate. Determine air temperature rise as follows:
a. Place thermometers in return and supply ducts as near furnace as
possible. Be sure thermometers do not see heat exchanger so that
radiant heat does not affect 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: Temperature rise can be determined for low-heat operation by
placing setup switch SW1-2 on furnace control in ON position. For
high-heat operation, place setup switch SW1-2 in OFF position and
jumper R-W2 on furnace control. DO NOT forget to return setup switch
to OFF position and remove R-W2 jumper upon completion of testing.
c. This furnace is capable of automatically providing proper airflow
to maintain the temperature rise within the range specified on
furnace rating plate. If temperature rise is outside this range,
proceed as follows:
(1.) Check gas input for low- and high-heat operation.
(2.) Check derate for altitude if applicable.
(3.) Check all return and supply ducts for excessive restrictions
causing static pressure greater than 0.5-In. W.C.
(4.) Ensure Comfort/Efficiency SW 1-4 on furnace control is in
OFF=Efficiency position when a bypass humidifier is used.
(See Fig.36 for switch location.)
(5.) Make sure proper model plug is installed.
d. Remove thermostat jumpers and release blower access door
switch.
e. Repeat Steps a through c as required to adjust for high heat
temperature rise.
f. When correct high heat input rate and temperature rise is
achieved, turn gas valve ON/OFF switch to OFF.
g. Release blower access door switch.
h. Remove manometer or similar device from gas valve.
i. Re-install manifold pressure tap plug in gas valve. (See Fig. 21).
j. Remove thermostat jumper wire from furnace control board.
k. Turn gas valve ON/OFF switch to ON.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in shorten furnace life.
Set air temperature rise within limits specified on the rating plate to
prevent reduced life of furnace components. Operation is within a few
degrees of the mid-point of rise range when setup switch SW1-4 is
OFF.
CAUTION
!
UNIT 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.
Temperature rise must be within limits specified on unit rating plate.
Operation is within a few degrees of midpoint of rise range when setup
switch SW1-4 is OFF.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Reinstall manifold pressure tap plug in gas valve to prevent gas leak.
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