I.O.M. •
E
LECTRIC
D
UCT
H
EATER
13
Environmental Technologies, Inc. •©June, 2001 • Electric Duct Heater IOM
8. If the heater always remains energized when power is applied, remove the wire from P4 of the
interface circuit board. If the heat remains on, there is a wiring error or the SSR is defective.
CAUTION: Remove Power From the Unit Before Proceeding With the Next Step.
9. If the heater is always de-energized when power is applied, remove the line and load connections to
the proportional heat control and temporarily tie them together. If the system is a three phase
arrangement, do the phases one at a time. (NOTE:
Always
remove power from the unit before
moving to the next phase). Make sure there is no danger of the temporary connection shorting to
another component or the chassis. Briefly reapply power. If the section of heat under test now
energizes, the SSR is defective. If heater still will not energize, one of the heater safety devices
(limits, safety contactor or airflow switch) or elements is defective.
THERMOSTAT
10. Make sure the temperature being sensed by the thermostat is within its control range:
MODEL
RANGE
ETSTAT4H
55° - 85° F
ETSTAT4H1
45° - 75° F
ETSTAT4H2
55° - 85° F
ETSTAT4H3
90° - 120° F
ETSTAT4H4
105° - 135° F
11. Set the thermostat setpoint to the temperature of the air being sensed. Read the voltage between
terminals 3 (ETSTAT4H) or terminal 5 (all other models) and terminal 2, and verify voltage is between
7 and 9 VDC. If not, replace thermostat (and duct sensor, if applicable).
12. Turn thermostat setpoint up approximately 4°F and verify voltage in step 11 increases by about two
volts. If not, replace thermostat (and duct sensor, if applicable).
