Tempstar F97CMN Installation, Start-Up, Operating And Service And Maintenance Instructions page 53

F97CMN and G97CMN: Installation, Start-up, Operating and Service and Maintenance Instructions
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Inlet pressure tap set screw must be tightened and ⅛-in. NPT pipe plug
must be installed to prevent gas leaks.
14. Tighten set screw on inlet tower pressure tap with 3/32-in. hex
wrench, or if 1/8-in. NPT plug was removed, apply pipe dope
sparingly to end of plug and re-install in the gas valve.
Adjust Manifold Pressure - Maximum Heat
For proper operation and long term reliability, the manifold pressure
must be adjusted within +/-2 percent of input rate on furnace rating plate.
The modulating furnace manifold pressure is set at two points. The first
point is Maximum Heat. The second point is Minimum Heat. Do not
adjust Intermediate Heat manifold pressure. Intermediate Heat manifold
pressure is checked as part of the temperature rise, but is not adjustable.
Always adjust Maximum Heat first, then Minimum Heat.
!
DO NOT set Maximum Heat manifold pressure less than 3.2-in. w.c. or
more than 3.8 in. w.c. for natural gas. If required manifold pressure is
outside this range, change main burner orifices to obtain manifold
pressure in this range.
To adjust manifold pressure to obtain input rate for Maximum Heat:
1. Make sure the gas supply is turned off to the furnace and at the
electric switch on the gas valve.
2. Loosen set screw on manifold tower pressure tap no more than one
full turn with a 3/32-in. hex wrench, or remove the 1/8 in. NPT plug
from the manifold pressure tap on the gas valve, see
Fig. 61 – Gas Valve with Tower Pressure Ports
3. Connect a manometer to the outlet pressure tap on gas valve.
4. Turn on furnace power supply.
5. Turn gas supply manual shutoff valve to ON position.
6. Turn furnace gas valve switch to ON position.
7. Jumper the R to W/W1 and W2 thermostat connections at the
furnace control board.
8. After the main burners ignite and the blower starts, confirm
Maximum Heat manifold pressure is correct, based on the manifold
pressure tables in the installation instructions.
9. To adjust the Maximum Heat manifold pressure, slowly turn
adjusting screw counterclockwise to decrease manifold pressure or
clockwise to increase manifold pressure. Turn adjustment no more
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
NOTICE
Fig.
than one click per second until you obtain the required manifold
pressure, see
Fig. 62 – Gas Valve without Tower Pressure Ports
10. Main burner flame should be clear blue, almost transparent.
11. After adjusting the Maximum Heat manifold pressure, remove
jumpers across thermostat connections to terminate the call for
heat.
12. Wait for blower off-delay to finish then reset 115-v power to
furnace.
Adjust Manifold Pressure - Minimum Heat
To adjust manifold pressure to obtain input rate for Minimum Heat:
1. Turn SW1-2 ON and SW4-2 must be OFF.
2. Jumper R and W/W1 thermostat connections on control to start
furnace.
3. After the main burners ignite and the blower starts, confirm
Minimum Heat manifold pressure is correct, based on the manifold
56.
pressure tables in the installation instructions.
4. To adjust the Minimum Heat manifold pressure, slowly turn
adjusting screw counterclockwise to decrease manifold pressure or
clockwise to increase manifold pressure. Turn adjustment no more
than one click per second until you obtain the required manifold
pressure, see
5. After adjusting the manifold pressure, remove jumpers across
thermostat connections to terminate the call for heat. Wait until the
blower off delay is completed.
6. Move setup switch SW1-2 to the OFF position.
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
A170116
Manifold pressure tap set screw must be tightened and ⅛-in. NPT pipe
plug must be installed to prevent gas leaks.
Clocking The Meter
Verify natural gas input rate by clocking meter.
NOTE: Contact your HVAC distributor or gas supplier for metric gas
meter Tables, if required.
1. Turn off all other gas appliances and pilots served by the meter.
2. Move setup switches SW1-2 to ON position and SW4-2 to OFF.
This keeps furnace locked in low--heat operation when only W/W1
is energized or high heat operation when R to W/W1 and W2 are
jumpered.
53
Fig. 62.
Fig. 62.
WARNING
!
A10496