107
Table 74 —
Gas Heating Service Analysis
Table 75 —
Electric Heat Service Analysis
PROBLEM
CAUSE
REMEDY
Burners Will Not Ignite
Active alarm.
Check active alarms using
Comfort
Link Navigator display.
No power to unit.
Check power supply, fuses, wiring, and circuit breakers.
No power to IGC (Integrated Gas Control).
Check fuses and plugs.
Heaters off due to time guard to prevent short
cycling.
Check using
Comfort
Link Navigator display.
Thermostat or occupancy schedule set point not
calling for Cooling.
Check using
Comfort
Link Navigator display.
No gas at main burners.
Check gas line for air and purge as necessary. After purging
gas line of air, allow gas to dissipate for at least 5 minutes
before attempting to re-light unit.
Water in gas line.
Drain water and install drip.
[Post Filter Option Only] Air Flow Switch.
Check switch and wiring. Switch closes when supply fan
operating.
Inadequate Heating
Dirty air filters.
Replace air filters.
Gas input too low.
Check gas pressure at manifold. Refer to gas valve
adjustment in Installation, Start-up, and Service Manual.
Thermostat or occupancy schedule set point only
calling for W1.
Allow time for W2 to energize.
Unit undersized for load.
Decrease load or increase of size of unit.
Restricted airflow.
Remove restriction.
Too much outdoor air.
Check economizer position and configuration. Adjust
minimum position using
Comfort
Link Navigator
display
.
Limit switch cycles main burners.
Check rotation of blower, thermostat heat anticipator
settings, and temperature rise of unit. Adjust as needed.
[Modulating Gas Only] No 24 vac at Modulating Gas
Module.
Check transformers TRAN4 and TRAN5 in gas section.
[Modulating Gas. Only] Modulating gas valve is not
operating.
Check for 4 to 20 mA control signal. Check for 24 VAC
power at SC-30 and TR1.
[Post Filter Option Only] Filter Temperature Switch
Open.
Check 4 filter temperature switches located on face of post
filters. Switch opens on high temperature.
Poor Flame Characteristics
Incomplete combustion (lack of combustion air)
results in: Aldehyde odors, CO, sooting flame, or
floating flame.
Check all screws around flue outlets and burner
compartment. Tighten as necessary.
Cracked heat exchanger, replace.
Unit is over-fired, reduce input. Adjust gas line or manifold
pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Burners Will Not Turn Off
Unit is in Minimum on-time.
Check using
Comfort
Link Navigator display.
Unit running in Service Test Mode.
Check using
Comfort
Link Navigator display.
PROBLEM
CAUSE
REMEDY
No Heat
Power failure.
Check power source. Call power company.
Fuse blown or circuit breaker tripped. Check fuses
and circuit breakers in power, control and electric
heat panels.
Replace fuse or reset circuit breaker.
Thermostat occupancy schedule set point not calling
for Heating.
Check using
Comfort
Link Navigator
display.
No 24 vac at primary contactor.
Check transformer and circuit breaker.
No power (high voltage) to L2 of primary contactor. Check safety switches manual reset limit, airflow switch, and
auto limit.
Bad electrical elements.
Power off unit and remove high voltage wires. Check
resistance of heater, replace if open.
[SCR Only] No 24 vac at SCR or Step Controller.
Check transformer and connections.
[SCR Only] Vernier step controller not staging up.
Check for 4 to 20 mA control signal. Check for 24 vac power
to step controller.
[Post Filter Option Only] Filter temperature switch
open.
Check for filter temperature switches located on face of post
filters. switch opens on high temperature.
Inadequate Heating
Dirty air filters.
Replace air filters.
Restricted airflow.
Remove restriction.
Heat Will Not Turn Off
Contactor failed closed.
Inspect contactors to look for welded-closed contacts.
Содержание WeatherExpert 48N2
Страница 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Страница 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Страница 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Страница 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Страница 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Страница 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Страница 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Страница 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Страница 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Страница 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Страница 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Страница 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Страница 168: ...168 Fig 47 Sensor and Ignition Position Fig 48 Combustion Blower Details SENSOR DETAILS IGNITION DETAILS ...
Страница 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...