Enviro VDD User Manual

ENVIRO-TEC
28
FORM ET115.24-NOM12 (718)
Problem Possible cause Corrective action
Electric heater is
overheating
CAUTION:
UNIT MAY BE
EXTREMELY
HOT. TAKE
GREAT CARE
WHILE
TROUBLE-
SHOOTING
Insufcient airow
Verify that airow is sufcient to provide a minimum of
70 CFM per kW of electric heat. Heater is not designed
to operate below 70 CFM/kW.
Improper duct connections
Electric heaters require even airow across the face of the
heater in order to operate properly. Verify ductwork is in-
stalled 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. Verify all jumpers installed on
terminal strip per schematic.
Damaged heater elements
Remove power from unit. Access the heater compartment.
Verify heating elements are undamaged.
Safety magnetic heater contactor
short
Remove heater command signal. Verify loss of 24VAC at
heater contactor. If electric heat continues to operate and
all wiring has been veried, replace contactor.
Solid State heater relay (SSR)
short
Remove heater command signal. Verify loss of 24VAC at
SSR. If electric heat continues to operate and all wiring
has been veried, replace contactor.
Insufcient
heating
INSUFFICIENT
HEATING
CAUTION:
UNIT MAY BE
EXTREMELY
HOT. TAKE
GREAT CARE
WHILE
TROUBLE-
SHOOTING
Intermittent demand for heating.
Heater short cycling.
Review schematic. For standard heaters, there needs
to be continuous 24VAC at heater control 'W' terminal
during demand for heat. For multi-stage units, verify
continuous demand signal at W and S2 terminal. For units
with proportional heater control, verify continuous analog
signal at SSR COM and SIG terminals.
Open or damaged heater elements
Remove power. Access heater compartment to inspect
heater coils. Note that dual motor units have two separate
heater racks.
Loss of stage
Loss of demand for second stage. Verify 24VAC at coil
for stage 2 contactor.
Incorrect voltage applied Verify proper voltage to unit per unit label.
Electric heat contactor fault
Verify 24VAC at coil terminal for each electric heat
contactor. 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
minimum required CFM. Possible turbulent airow.
Verify ductwork complies with ASHRAE Fundamentals
Handbook, SMACNA, NFPA 90A and local code.
Possible under sized transformer. Verify 24VAC voltage.
Primary limit switch cycling
24VAC on EH signal wire but not at airow switch
signies primary limit has tripped. If limit continues to
trip, verify that heater is not overheating. Verify sufcient
airow and proper ductwork connections. NOTE: dual
blower units have two heater racks and two primary limits.

Enviro VDD Specifications

General

Brand	Enviro
Model	VDD
Category	Fan
Language	English