Enviro VDD User Manual

ENVIRO-TEC
27
FORM ET115.24-NOM12 (718)
Problem Possible cause Corrective action
Electric Heat
shuts down
unexpectedly
Loss of demand
Verify that heat command signal is not dropping out.
Review schematic. For standard heaters, verify 24VAC at
heater control ‘W’ terminal. For multi-stage units, verify
demand at W and S2 terminal. For units with proportional
heater control, verify analog signal at COM and SIG
terminals of Heat controller.
Loss of fan speed command
Heater will not operate if fan is not enabled. Verify
24VAC at fan relay coil and contact with EH command
wire.
Insufcient airow
Unit must have sufcient airow to allow airow switch
to make. Verify airow switch is enabled: there should
be 24VAC present at each side of switch while fan is
running.
Primary limit switch tripped
24VAC on EH signal wire but not at airow switch
signies primary limit has tripped. The primary limit
switch(es) will auto-reset once the unit cools down. This
may take up to an hour. If limit trips again, verify heater
is not overheating. NOTE: dual blower units have two
primary limits.
Secondary (high) limit switch
tripped
The secondary limit may be manually reset. If unit is hot,
wait for the heater to cool down. This may take up to an
hour. Reset switch(es). If limits trip again, verify heater is
not overheating. NOTE: dual motor units have two heater
racks.
Intermittent control device
Verify operation of any control device such as drain pan
oat switch, freeze stat, etc. When in doubt, jumper out
and verify fan operation.
Loose wiring
Remove power from unit. Verify and/or tighten all wiring
connections.

Enviro VDD Specifications

General

Brand	Enviro
Model	VDD
Category	Fan
Language	English