Enviro VDD User Manual

ENVIRO-TEC
26
FORM ET115.24-NOM12 (718)
Problem Possible cause Corrective action
Electric Heat
will not operate
(cont.)
Damaged electric heat wire
harness
With power removed, disconnect heater wire harnesses.
Use a volt-ohm meter to verify continuity of electric heat
power harness wires in the control enclosure section.
Secondary (high) Limit switch
fault
Remove power from unit. Wait for unit to completely
cool down. This may take up to an hour. Remove
secondary limit switch from circuit. Verify continuity
across (cooled) switch terminals. Replace switch if no
continuity.
[Magnetic contactor] Electric
heat contactor fault
Verify heating demand voltage is at magnetic 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 may need to be removed to access
manual operator. Replace contactor if faulty.
Contactor chattering
Possible insufcient airow. Verify unit develops mini-
mum required CFM. Possible turbulent airow. Verify
ductwork complies with ASHRAE Fundamentals Hand-
book, SMACNA, NFPA 90A and local code. Possible
undersized transformer. Verify 24V AC voltage.
[Solid state relay] electric heat
safety contactor fault
Verify 24V AC control voltage is at magnetic electric heat
safety contactor control coil terminals. If power is present
at coil but contactor is not actuated, replace contactor. If
power is not present at coil, verify primary limit switch.
[On/Off Solid state relay] Solid
State Relay fault
Verify heating demand (24VAC control voltage) is at solid
state relay control terminals. If power is present but relay
is not actuated, replace relay.
[Solid state relay with
proportional control] Heat
controller fault
Verify analog DC control signal is present at controller
SIG and COM input terminals. Verify that output control
voltage to solid state relay varies with variation in analog
input. Replace controller if not.
[Solid state relay with
proportional control] Solid
State Relay fault
If proportional heat controller not faulted, verify solid
state relay has DC control voltage at relay terminals. If
control voltage at terminals and relay fails to pass voltage
from safety contactor to heater, solid state relay is faulted.
Replace relay.

Enviro VDD Specifications

General

Brand	Enviro
Model	VDD
Category	Fan
Language	English