Table of Contents
Advertisement
1. Purge gas lines after all connections have been made.
2. Check gas lines for leaks.
3. To Begin Component Self- -Test:
Remove Blower Access Door. Disconnect the thermostat
R lead from furnace control board. Manually close blower
door switch. Turn Setup DIP switch SW1- -6 ON. (See Fig.
27, 59 and Table 8.)
4. Determine the correct orifice and manifold pressure
adjustment. All models in all positions except Low NOx
models in downflow and horizontal positions use Table 12
(22,000 Btuh per burner.) Low NOx models in downflow
or horizontal positions must use Table 13 (21,000 Btuh
per burner.) See input listed on rating plate.
EXAMPLE 1
88,000 BTUH INPUT FURNACE INSTALLED AT 4300 Ft.
Derate
Furnace Input
X
Multiplier
Rate
at Sea Level
Factor
88,000
X
0.90
a. Obtain average yearly gas heat value (at installed
altitude) from local gas supplier.
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.
Refer to service label attached to furnace or See Fig. 58.
Component test sequence is as follows:
a. Inducer motor starts on high- -speed and continues to
run until Step d. of component test sequence.
b. Hot surface igniter is energized for 15 sec., then off.
c. Blower motor operates for 15 sec.
d. Inducer motor goes to low- -speed for 10 sec., then
stops.
e. After component test is completed, one or more status
codes (11, 25, or 41) will flash. See component test
section of service label (Fig. 58) in furnace for
explanation of status codes.
NOTE: To repeat component test, turn setup switch SW1- -6
OFF, then back ON.
5. Turn setup DIP switch SW1- -6 OFF. Reconnect R lead to
furnace control board, release blower door switch and
reinstall blower access door.
6. Operate furnace per instruction on inner door.
7. Verify furnace shut down by lowering thermostat setting
below room temperature.
8. Verify furnace restarts by raising thermostat setting above
room temperature.
Adjustments
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal
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.
Furnace Input
Rate
=
at Installation
Altitude
=
79,200
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 Fig.
56.)
Furnace gas input rate on rating plate is for installations at
altitudes up to 2000 Ft. Furnace input rate must be within +/- -2
percent of furnace rating plate input. For altitudes above 5500 Ft.,
a field- -supplied high altitude pressure switch is required.
1. Determine the correct gas input rate.
In the U.S.A.: The input rating for altitudes above 2,000
ft. must be reduced by 4 percent for each 1,000 ft. above
sea level.
For installations below 2000 Ft., refer to the unit rating
plate. For installations above 2000 Ft., multiply the input
on the rating plate by the de- -rate multiplier in Table 9 for
the correct input rate.
In Canada: The input rating for altitudes from 2,000 to
4,500 ft. above sea level must be derated 10 percent by an
authorized Gas Conversion Station or Dealer.
To determine correct input rate for altitude, see example
and use 0.90 as derate multiplier factor.
Table 7 – Altitude Derate Multiplier for U.S.A.
ALTITUDE
PERCENT
(FT.)
OF DERATE
0–2000
0
2001–3000
8–12
3001–4000
12–16
4001–5000
16–20
5001–6000
20–24
6001–7000
24–28
7001–8000
28–32
8001–9000
32–36
9001–10,000
36–40
f. Obtain average yearly gas specific gravity from local
gas supplier.
g. Find installation altitude in Table 11 or 12.
h. Find closest natural gas heat value and specific gravity
in Table 11 or 12.
i. Follow heat value and specific gravity lines to point of
intersection to find orifice size and low- -and high- -heat
manifold pressure settings for proper operation.
j. Check and verify burner orifice size in furnace.
NEVER ASSUME ORIFICE SIZE. ALWAYS
CHECK AND VERIFY.
k. Replace orifice with correct size, if required by Table
11 or 12. Use only factory- -supplied orifices. See
EXAMPLE 2.
39
DERATE MULTIPLIER
FACTOR*
1.00
0.90
0.86
0.82
0.78
0.74
0.70
0.66
0.62
Advertisement
Table of Contents
