6.Adjustments to the firing rate can be made by adjusting the gas manifold pressure. See the High Altitude Application section for additional information of firing rate at elevations above 2000 ft.
The manifold pressure must be set to the ap- propriate value for your installation. Refer to either Table 8 for natural gas or Table 9 for LP/propane gas to verify the manifold pressure setting required for your particular installation.To adjust the manifold pressure, remove the regula- tor cap and turn the adjusting screw clockwise to increase pressure or counterclockwise to reduce pressure. Replace the regulator cap after adjustments are complete.
!CAUTION:
Do not
Verifying and Adjusting
Temperature Rise
Verify that the temperature rise through the furnace is within the range specified on the furnace rating plate. Temperature rises outside the specified range could result in premature heat exchanger failure.
Place thermometers in the return and supply air stream as close to the furnace as possible. The thermometer on the supply air side must be shielded from direct radiation from the heat exchanger to avoid false readings. Adjust all registers and duct dampers to the desired position and run the furnace for fifteen minutes before taking any temperature readings. The temperature rise is the difference between the supply and return air temperatures.
For typical duct systems, the temperature rise will fall within the range specified on the rat- ing plate with the blower speed at the factory recommended setting. If the temperature rise measured is outside the range specified, it may be necessary to change the blower speed.Lower blower speeds will increase the temperature rise and higher blower speeds will decrease the temperature rise.
The furnace is equipped with a multispeed motor. Heating and cooling speed selection is made by moving the leads on the integrated control board located in the furnace. The wiring diagram on the furnace and Figures 27, 28 and 29 show the speed taps for adjusting motor speed.
If it is desired that the blower operate at the same speed for heating and cooling, tape off the terminal of the unused blower wire. Install the jumper wire, found in the plastic instruction bag, across the HEAT and COOL taps on the
| R | |
| C | |
| Y | |
| G | |
| W | |
Common |
| |
Leads | EAC | |
Connect | ||
HUM | ||
Neutral | ||
| ||
Lead of |
| |
Electronic |
| |
Air Cleaner |
| |
and/or Humidifier |
| |
Here. |
|
COM
24 V
9 | 6 | 3 |
8 | 5 | 2 |
7 | 4 | 1 |
Neutrals
6 3
52
41
3 Amp Fuse
Unused Motor
Leads
|
|
|
|
|
|
|
HUM |
| M1 | M2 | M3 |
| |
|
| |||||
Flame Signal
Light (Yellow)
Status
Light (Red)
HEAT | COOL | EAC | XFMR | L1 |
Electronic Air Tap (.5A@ 120 VAC)
Humidifier Tap | Heating |
(.5A@ 120 VAC) | Speed Tap |
Cooling Speed Tap
Figure 28. Blower Speed Tap Location
33
