35
VersiVent Energy Recovery Ventilator
Troubleshooting – Unit
Symptom
Possible Cause
Corrective Action
Blower fails to
operate
Blown fuse or open circuit breaker.
Replace fuse or reset circuit breaker and check
amps.
Defective motor or capacitor.
Replace.
Motor overloaded.
Reset VFD and check amps.
Electrical.
Check for On/Off switches. Check for correct
supply voltage. Check Control wiring.
One or both
blowers turn off
intermittently and
back on after two
minutes
Blower fan motor overloads are tripping and auto-
resetting.
Decrease fan speed.
Exhaust only frost control sensors are tripping.
Adjust frost temperature sensor set point as
needed.
Motor starters
“chatter” or do not
pull in
Control power (24 VAC) wiring run is too long.
(Resistance should not exceed 0.75 ohms).
Shorten wiring run to mechanical room or install a
relay to turn unit on/off. Consult factory for relay
information. Increase wire gauge size so that
resistance is 0.75 ohms or less.
Incoming supply power is less than anticipated.
Voltage supplied to starter coil must be within
+10% / -15% of nominal voltage stated on the coil.
Need to increase supply power or use a special
control transformer which is sized for the actual
supply power.
Motor over amps
Static pressures are higher than design.
Check for dirty filters. Improve ductwork.
Motor voltage incorrect.
Check motor wiring. Check motor nameplate
versus supplied voltage.
Motor horsepower too low.
See specifications and catalog for fan curves to
determine if horsepower is sufficient.
Shorted windings in motor.
Replace motor.
Low airflow (cfm)
Unit damper not fully open.
Adjust damper linkage or replace damper motor.
System static pressure too high.
Improve ductwork to eliminate losses using good
duct practices.
Blower speed too low.
Check maximum motor RPM and compare with
catalog data. Verify that external control wiring is in
place if required.
Fan wheels are operating backwards.
For 3-phase, see Direction of Fan Wheel Rotation in
Start-Up Components section.
Dirty filter.
Replace filters or follow cleaning procedures in
Routine Maintenance section of this manual.
Leaks in ductwork.
Repair.
Elbows or other obstructions may be obstructing
fan outlet.
Correct or improve ductwork.
High airflow (cfm)
Blower fan speed too high.
Check for correct maximum fan RPM. Decrease
maximum fan speed if necessary with the variable
frequency drive.
Filter(s) not in place.
Install filters.
Insufficient static pressure (Ps).
(airflow resistance)
Induce Ps into system ductwork. Make sure grilles
and access doors are installed. Decrease fan speed
if necessary.
Excessive noise or
vibration
Fan wheel rubbing on inlet.
Adjust wheel and/or inlet cone. Tighten wheel hub
or bearing collars on shaft.
Bearings.
Replace defective bearing(s). Lubricate bearings.
Tighten collars and fasteners.
Loose wheel on shaft.
Tighten wheel hub.
Motor base or blower loose.
Tighten mounting bolts.
Noise being transmitted by duct.
Make sure ductwork is supported properly. Make
sure ductwork metal thickness is sized for proper
stiffness. Check duct size at discharge to ensure
that air velocities are not too high.
