Manual 2100628
Page
13 of 24
HUMIDITY CONTROL OPTION
When two units are controlled and connected with
the MV4001K-B, they can be adapted to perform
dehumidification with the addition of a simple humidity
controller that closes-on-rise, and is connected to
terminals "H1" and "H2" on the main controller board
(see Figure 8 on page 15). Recommended is Bard Part
# 8403-038 (H600A 1014).
NOTE: Both HVAC units
must be equipped with electric resistance heat for this
sequence to work properly.
1. Temperature control always has priority over
dehumidification. If there is any stage of cooling
demand active, the dehumidification sequence is
locked out.
2. If all stages of cooling are satisfied, and relative
humidity is above the set point of the humidity
controller.
a. The Green "Dehumid Operation Light" will come
on, and the lag unit compresser and blower will
operate until the set point of humidty controller
is satisfied (or cancelled by a call for cooling).
b. If the space temperature drops to 19.4°C, the
electric heater of the lead unit will cycle to help
maintain building temperature. It will cycle off
at 20.6°C.
c. If the space temperature drops to 17.8°C,
the "Stage 2 Heating Light" will come on,
and the lag unit compressor operation for
dehumidification mode will terminate until the
building temperature rises above18.3°C from
the 1st Stage heat and building load. The
Green "Dehumidification Light" will stay on
during this sequence, and when 2nd Stage
Heating light is "OFF", the compressor is "ON".
The electric resistance heater in the lag unit is
locked out in dehumidification mode.
Lag Unit outputs G, Y1, and Y2 are all switched
one during dumidification sequence. This is true
for both alternating and non-alternating controller
configurations.
