E
LECTRIC
D
UCT
H
EATER
•
I.O.M.
12
Electric Duct Heater IOM • ©June, 2001 • Environmental Technologies, Inc.
CAUTION:
Lethal voltages are present in the heater control enclosure. Use extreme caution
when taking measurements in these units. Always disconnect power before
removing or re-applying any connections.
1. Before applying power, verify wiring matches diagram in cover of heater control enclosure, and that
correct line voltage has been wired to heater line block.
2. Verify 24 VAC +15% or -10% between P1 and P2 of interface circuit board (ETPHCI, ETPHCT, etc.,
depending on input).
3. If the heat control is used with an ENVIRO-TEC
®
duct or wall stat, 18 VDC + or -0.5 VDC
between the terminals l18 and COM on the interface circuit board, and terminals 1 and 2 of
the thermostat. If no voltage is present, check the fuse on the interface circuit board and, if good,
replace the interface circuit board.
4. The table below lists responses to input signal by interface model as explained in step 5. If the volt-
ages from an ENVIRO-TEC
®
thermostat listed in the table cannot be obtained, proceed to step 10. If
any of the other inputs cannot be obtained, refer to the literature on the device which is supposed to
provide the input. Otherwise, proceed to step 5.
INTERFACE
“PULSE”
FULL OFF
FULL ON
MODEL
INPUT
INPUT
INPUT
ETPHCI
12.0 mA
4.0 mA
20.0 mA
ETPHCT
9.1 VDC
8.4 VDC
9.9 VDC
ETPHCR
68
Ω
0
Ω
135
Ω
ETPHCV1
7.5 VDC
6.0 VDC
9.0 VDC
ETPHCV2
6.0 VDC
2.0 VDC
10.0 VDC
5. Apply Full Off Input per table above. If the unit is three phase, verify that the LED on the SSR (solid
state relay) is off. If the unit is single phase, measure voltage between P4 and P6 and verify 0.3 VDC
+ or - 0.3 VDC. Replace the interface circuit board if the voltage is higher than specified, or the LED
is on.
6. Apply Full On Input per table above. If the unit is three phase, verify that the LED on the SSR (solid
state relay) is on. If the unit is single phase, measure voltage between P4 and P6 and verify between
3 and 5 VDC.
7. Apply “Pulse” Input per table above. If the unit is three phase, verify that the LED on the SSR (solid
state relay) is flashing at an interval of about one second. If the unit is single phase, the voltage
between P4 and P6 of the master circuit board should vary between the Full Off and Full On voltages
in steps 5 and 6 in intervals of about one second. NOTE: Some voltmeters will not respond this quick-
ly, so the value of the voltages may not appear to be correct; however, if the voltage appears to be
changing at regular intervals, it may be assumed that this function is operating properly. This com-
pletes the low voltage portion of the unit test.
P
ROPORTIONAL
H
EAT
C
ONTROL
(SSR) T
ROUBLESHOOTING
G
UIDE
