KRUEGER A Series User Manual

42
KHF - SERIES A FAN COIL UNITS
INSTALLATION, OPERATION, AND MAINTENANCE MANUAL
ELECTRIC HEATER (CONTINUED)
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
ELECTRIC HEATER IS
OVERHEATING
CAUTION: UNIT MAY BE
EXTREMELY HOT. TAKE
GREAT CARE WHEN
TROUBLESHOOTING.
Insucient airow Verify that airow is sucient to provide a minimum of 70 CFM per kW of electric heat.
Improper duct connections
Electric heaters require even airow across the face of the heater in order to operate properly.
Verify ductwork is installed per SMACNA and ASHRAE guidelines.
Obstructed ductwork Verify no obstructions. Verify all dampers are full open while fan operates.
Intermittent fan Verify fan motor runs continuously, providing even airow.
Incorrect voltage applied Verify proper voltage to unit per unit label.
Improper wiring connections
Verify wiring to schematic. If Fan Coil Relay board present, verify all jumpers and harnesses installed.
Refer to Fan Coil Relay Board Troubleshooting Guide.
Damaged heater elements Remove power from unit. Access the heater compartment. Verify heating elements are undamaged.
Shorted magnetic heater contactor
Remove thermostat or control command signal. Verify no control voltage to heater contactor.
If electric heat continues to operate and all wiring has been veried, replace contactor.
[Solid state relay] Shorted solid state relay
Remove thermostat or control command signal. Verify no control voltage to solid state relay.
If electric heat continues to operate and all wiring has been veried, replace solid state relay.
INSUFFICIENT HEATING
CAUTION: UNIT MAY BE
EXTREMELY HOT. TAKE
GREAT CARE WHEN
TROUBLESHOOTING
Intermittent demand for heating
Verify that thermostat or control command signal is not dropping out.
Verify voltage is continuously present at unit during demand for heat.
Heater is short cycling Verify thermostat settings. Verify proper location of thermostat.
Open or damaged heater elements
With power removed, disconnect heater wire harnesses. (These are the harnesses with the black plugs.) Use
a volt-ohm meter to measure the resistance across the electric heat power harness coming out of the heater
section. Verify ohms approximately equal to (Unit Volts)2/Unit kW.
Loss of stage Loss of demand for second stage. Verify demand voltage at stage 2 contactor.
Incorrect voltage applied Verify proper voltage to unit per unit label.
Electric heat contactor fault
Verify heating demand voltage is at each electric heat contactor control coil terminals. If power is present but
contactor is not actuated, replace contactor. To verify contactor: with power removed, unwire contactor and
verify continuity across contacts when manually operated. Cover of contactor will need to be removed to access
manual operator. Replace contactor if faulty.
Primary limit switch cycling
Verify no loss of demand to unit. Verify that voltage exists continuously on heater contactor during demand for
heat. If demand reaches unit but not contactor, primary limit is tripped. The primary limit switch(es) will auto-
reset once the unit cools down. If unit is hot, wait for heater to cool down. This may take up to an hour. If limit
trips again, verify heater is not overheating.
TROUBLESHOOTING (CONTINUED)

KRUEGER A Series Specifications

General

Brand	KRUEGER
Model	A Series
Category	Fan
Language	English