Table of Contents
Advertisement
5.
Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6.
Is gas turned on at the meter?
7.
Is the manual main shut–off valve open?
8.
Is the internal manual shut–off valve open?
9.
Is the unit ignition system in lockout? If the unit locks
out again, inspect the unit for blockages.
Heating Sequence of Operation
1. When thermostat calls for heat, combustion air inducer
starts.
2.
Combustion air pressure switch proves blower
operation. Switch is factory set and requires no
adjustment.
3.
After a 15 second pre-purge, the hot surface ignitor
energizes.
4.
After a 20 second ignitor warm-up period, the gas
valve solenoid opens. A 4-second "Trial for Ignition"
period begins.
5.
Gas is ignited, flame sensor proves the flame, and the
combustion process continues.
6.
If flame is not detected after first ignition trial, the
ignition control will repeat steps 3 and 4 four more
times before locking out the gas valve. The ignition
control will then automatically repeat steps 1 through
6 after 60 minutes. To interrupt the 60 minute period,
move thermostat from "Heat" to "OFF" then back to
"Heat". Heating sequence then restarts at step 1.
Gas Pressure Adjustment
Gas Flow (Approximate)
Gas Meter Clocking Chart
Seconds for One Revolution
Natural
Capacity
1 cu ft
Dial
-045
80
-070
55
-090
41
-110
33
Natural-1000 btu/cu ft LP-2500 btu/cu ft
Table 13.
Furnace should operate at least 5 minutes before checking
gas flow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in
Figure 65 or Figure 66. If manifold pressure matches Table
15 and rate is incorrect, check gas orifices for proper size
and restriction. Remove temporary gas meter if installed.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Page 46 of 56
LP
2 cu ft
1 cu ft
2 cu ft
Dial
Dial
Dial
160
200
400
110
136
272
82
102
204
66
82
164
Supply Pressure Measurement
When testing supply gas pressure, use the 1/8" N.P.T.
plugged tap or pressure post located on the gas valve to
facilitate test gauge connection. See Figure 67. Check
gas line pressure with unit firing at maximum rate. Low
pressure may result in erratic operation or underfire. High
pressure can result in permanent damage to gas valve or
overfire.
On multiple unit installations, each unit should be checked
separately, with and without other units operating. Supply
pressure must fall within range listed in Table 15.
Manifold Pressure Measurement
1. Remove the threaded plug from the outlet side of
the gas valve and install a field provided barbed
fitting. Connect to a manometer to measure manifold
pressure.
2.
Start unit and allow 5 minutes for unit to reach steady
state.
3.
While waiting for the unit to stabilize, observe the
flame. Flame should be stable and should not lift from
burner. Natural gas should burn blue.
4.
After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
Table 15.
NOTE: Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to remove
barbed fitting and replace threaded plug.
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue
outlet and compare to the tables below.
Capacity
All
The maximum carbon monoxide reading should not exceed
100 ppm.
High Altitude Information
NOTE: In
Canada,
elevations over 4500 feet (1371 m) is the jurisdiction of
local authorities.
Units may be installed at altitudes up to 10,000 ft. above
sea level. See Table 15 for de-rate manifold values. Units
installed at altitude of 7501 - 10,000 feet require an orifice
change. Units installed at altitudes of 4,501 - 10,000 feet
(1371 -3048 m) may require a pressure switch change
which can be ordered separately.
Issue 2223
CO
% for Nat
CO
% for L.P.
2
2
7.5 - 8.5
8.2 - 9.5
Table 14.
certification
for
installations
507768-05G / 31-5000655
at
Advertisement
Table of Contents
