Page 20
A67 (RH1) BOARD LOCATION ON M1 BOARD
A55 (M1):
A56
(EM1)
A67
(RH1)
A67 (RH1) REHEAT
CONTROL BOARD
FIGURE 21
FLASHING GREEN
NHEARTBEAT" LED
INDICATES NORMAL
OPERATION
1
P175
HUMIDITROL
PLUG
YELLOW LED
INDICATES OUTPUT TO
L14 REHEAT VALVE
A67 (RH1)
L14 Reheat Coil Solenoid Valve
When IMC board input (P114−10) indicates room
conditions require dehumidification, L14 reheat valve is
energized (RH1 board P175−3) and refrigerant is routed
to the reheat coil.
RH1 Humiditrol Board
The RH1 add−on board is factory−installed in all
Humiditrol units. RH1 is located on the M1 board as
shown in figure 21.
Reheat Setpoint
Reheat is factory−set to energize when indoor relative
humidity rises above 60% (default). Reheat will terminate
when the indoor relative humidity falls 3% below setpoint,
or 57% (default). The reheat setpoint can be adjusted by
changing ECTO 4.25. A setting of 100% will disable
reheat.
A91 Humidity Sensor
Install humidity sensor in the conditioned space
according to instructions provided with sensor.
Relative humidity should correspond to the sensor (A91)
output voltage listed in table 17. For example: if indoor air
relative humidity is 80% + 3%, the humidity sensor output
should read 8.00VDC.
Check the sensor output annually for accuracy. Keep the
air intake openings on the sensor clean and free of
obstructions and debris.
Read Relative Humidity At IMC
Turn MODE DIP HTEMP" switch #4 HON". Display will
alternately flash from readout to output. A single push on
the pushbutton will toggle the readout upward from .0 to .7
incrementally. A double push will toggle the readout
downward from .7 to .0 incrementally. Readout .7
indicates percent relative humidity.
Check−Out
Test Humiditrol operation using the following procedure.
1− Make sure RH sensor is wired as shown in figure
11 or 12.
2− Set IMC ECTO system mode parameter 6.01 to
option 0 (default local thermostat mode).
3− Set IMC ECTO reheat setpoint parameter 4.25 to
option 0 (% relative humidity).
4− Jumper the following TB1 terminals:
8&9 (occupied mode)
6&3 (blower demand G)
6&18 (Y1 cooling demand)
The blower and compressor should be operating. L14 LED
on the A67 board should be Off, indicating the reheat valve is
de−energized.
5− Disconnect the jumper between TB1 terminals 6 &18
(Y1) to end the cooling demand.
Compressor should continue to operate and L14 LED
should be ON indicating the reheat valve is energized.
6− Disconnect the jumper between TB1 terminals 8&9
(occupied mode).
Compressor should de−energize, L14 LED should go
OFF, blower should still be energized.
7− When check−out is complete, remove all jumpers,
set ECTO 4.25 back to the proper humidity
setpoint, and set ECTO 6.01 to the proper setting.
TABLE 17
Relative Humidity (%RH + 3%)
Sensor Output (VDC)
20
2.00
30
3.00
40
4.00
50
5.00
60
6.00
70
7.00
80
8.00
90
9.00
