Bryant 580J*08--14D Service And Maintenance Instructions page 33

Minimum Heating Entering Air Temperature
When operating on first stage heating, the minimum
temperature of air entering the dimpled heat exchanger is
50_F continuous and 45_F intermittent for standard heat
exchangers and 40_F continuous and 35_F intermittent for
stainless steel heat exchangers. To operate at lower
mixed- - air temperatures, a field- - supplied outdoor- - air
thermostat must be used to initiate both stages of heat
when the temperature is below the minimum required
temperature to ensure full fire operation. Wire the
outdoor- - air thermostat OALT (part no. HH22AG106) in
series with the second stage gas valve. (See Fig. 41.) Set
the outdoor- - air thermostat at 35_F for stainless steel heat
exchangers or 45_F for standard heat exchangers. This
temperature setting will bring on the second stage of heat
whenever the ambient temperature is below the thermostat
setpoint. Indoor comfort may be compromised when
heating is initiated using low entering air temperatures
with insufficient heating temperature rise.
PROBLEM
Burners Will Not Ignite.
Inadequate Heating.
Poor Flame
Characteristics.
Burners Will Not Turn
Off.
Table 13 – Heating Service Analysis
CAUSE
Misaligned spark electrodes.
No gas at main burners.
Water in gas line.
No power to furnace.
No 24 v power supply to control
circuit.
Miswired or loose connections.
Burned ---out heat anticipator in
thermostat.
Broken thermostat wires.
Dirty air filter.
Gas input to unit too low.
Unit undersized for application.
Restricted airflow.
Blower speed too low.
Limit switch cycles main burners.
Too much outdoor air.
Incomplete combustion (lack of
combustion air) results in:
Aldehyde odors, CO, sooting
flame, or floating flame.
Unit is locked into Heating mode
for a one minute minimum.
Thermostat
TH1
W1
TH2
W2
Fig. 41 - - OATL Connections
Troubleshooting Heating System
Refer to Table 13 and 14 for additional troubleshooting
topics.
REMEDY
Check flame ignition and sensor electrode positioning.
Adjust as needed.
Check gas line for air, purge as necessary. After purging
gas line of air, allow gas to dissipate for at least 5 minutes
before attempting to relight unit.
Check gas valve.
Drain water and install drip leg to trap water.
Check power supply, fuses, wiring, and circuit breaker.
Check transformer. Transformers with internal overcurrent
protection require a cool down period before resetting.
Check all wiring and wire nut connections.
Replace thermostat.
Run continuity check. Replace wires, if necessary.
Clean or replace filter as necessary.
Check gas pressure at manifold. Clock gas meter for input.
If too low, increase manifold pressure, or replace with
correct orifices.
Replace with proper unit or add additional unit.
Clean filter, replace filter, or remove any restrictions.
Use high speed tap, increase fan speed, or install optional
blower, as suitable for individual units.
Check rotation of blower, thermostat heat anticipator
settings, and temperature rise of unit. Adjust as needed.
Adjust minimum position.
Check economizer operation.
Check all screws around flue outlets and burner
compartment. Tighten as necessary.
Cracked heat exchanger.
Overfired unit — reduce input, change orifices, or adjust
gas line or manifold pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Wait until mandatory one ---minute time period has elapsed
or reset power to unit.
33
LCTB
W1
OALT
W2
C08442