Adjustments - International comfort products N8MSN Installation Instructions Manual

WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115−v power to
control. No component operation can occur unless
switch is closed. Caution must be taken when
manually closing this switch for service purposes.
3. To Begin Component Self−Test: Remove blower ac-
cess door. Disconnect the thermostat R lead from the
furnace control board. Manually close the blower door
switch. Short (jumper) the C terminal on control to the
TEST/TWIN 3/16−inch quick connect terminal on con-
trol until LED goes out (approximately 2 sec). Gas
valve and humidifier will not be turned on. (See
Figure 25)
NOTE: The furnace control allows all components, except
the gas valve, to be run for short period of time. This feature
helps diagnose a system problem in case of a component
failure. Component test feature will not operate if any
thermostat signal is present at the control.
Component test sequence is as follows:
Refer to service label attached to furnace or see Figure 44.
a. LED will display previous status code 4 times.
NOTE: If no previous code is present, go directly to b.
b. Inducer motor starts and continues to run until Step
f of component test sequence.
c. Hot surface igniter is energized for 15 sec., then off.
d. Blower motor operates on HEAT speed for 10 sec.
e. Blower motor operates on COOL speed for 10 sec.
f. Inducer motor stops.
g. Reconnect R lead to furnace control board, release
blower door switch and re−install blower door.
4. Operate furnace per instruction on door.
5. Verify furnace shut down by lowering thermostat setting
below room temperature.
6. Verify furnace restarts by raising thermostat setting
above room temperature.
Step 3 —Adjustments
Table 11—Altitude Derate Multiplier for U.S.A.
ALTITUDE PERCENT
FT. (M) OF DERATE
0–2000
0
(0−610)
2001–3000
8–12
(610−914)
3001–4000
12–16
(914−1219)
4001–5000
16–20
(1219−1524)
5001–6000
20–24
1524−1829)
6001–7000
24–28
(1829−2134)
7001–8000
28–32
(2134−2438)
8001–9000
32–36
(2438−2743)
9001–10,000
36–40
(2743−3048)
* Derate multiplier factors are based on midpoint altitude for altitude range.
441 01 1402 02
DERATE MULTIPLIER
FACTOR*
1.00
0.90
0.86
0.82
0.78
0.74
0.70
0.66
0.62
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in injury,
death and/or property damage.
DO NOT bottom out gas valve regulator adjusting
screw. This can result in unregulated manifold
pressure and result in excess overfire and heat
exchanger failures.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced
furnace life.
DO NOT redrill orifices. Improper drilling (burrs,
out−of round holes, etc.) can cause excessive burner
noise and misdirection of burner flames. This can
result in flame impingement of heat exchangers,
causing failures. (See Figure 42)
Furnace gas input rate on rating plate is for installations at
altitudes up to 2000 ft. (610 M). Furnace input rate must be
within +/−2 percent of furnace rating plate input.
1. Determine the correct gas input rate.
The input rating for altitudes above 2,000 ft. (610 M)
must be reduced by 4 percent for each 1,000 ft. (305
M) above sea level. For installations below 2000 ft.,
refer to the unit rating plate. For installations above
2000 ft. (610 M), multiply the input on the rating plate
by the derate multiplier in Table 11 for the correct input
rate.
2. Determine the correct orifice and manifold pressure ad-
justment. There are two different orifice and manifold
adjustment tables. All models in all positions, except
Low NOx models in downflow or horizontal positions,
use Table 15 (22,000 Btuh/Burner).
Low NOx models in the downflow or horizontal posi-
tions must use Table 16 (21,000 Btuh/Burner). See in-
put listed on rating plate.
a. Obtain average yearly gas heat value (at installed
altitude) from local gas supplier.
b. Obtain average yearly gas specific gravity from loc-
al gas supplier.
c. Find installation altitude in Table 15 or 16.
d. Find closest natural gas heat value and specific
gravity in Table 15 or 16.
e. Follow heat value and specific gravity lines to point
of intersection to find orifice size and manifold pres-
sure settings for proper operation.
f. Check and verify burner orifice size in furnace.
NEVER ASSUME ORIFICE SIZE. ALWAYS CHECK
AND VERIFY.
g. Replace orifice with correct size if required by Table
15 or 16. Use only factory−supplied orifices. See
EXAMPLE 2.
31