17
Marvair GAA A/C w/Gas Heat I&O Manual
06/2023 Rev.5
1.0 Indoor Blower Operation
The speed at which the indoor blower will operate is based on the discrete operational inputs that have
24vac applied. These inputs are listed below.
1.1 G Input –
A request for Fan Only (independent G-signal via Digital input or Modbus), results in
the indoor motor turning “ON” and operating at the “Y2” (BY DEFAULT) motor speed (Only
Applicable for EC motors).
1.2 Y1 Input –
A request for Y1 (independent Y1-signal via Digital input or Modbus), results in
the indoor motor turning “ON” and operating at the “Y1” motor speed (Only Applicable for EC
motors).
1.3 Y2 Input –
A request for Y2 (independent Y2-signal via Digital input or Modbus), results in
the indoor motor turning “ON” and operating at the “Y2” motor speed (Only Applicable for EC
motors).
1.4 W2 Input –
A request for W2 (independent W2-signal via Digital input or Modbus), results in
the indoor motor turning “ON” and operating at the “W2” motor speed (Only Applicable for
EC motors).
1.5 HUM Input –
A request for HUM (independent HUM-signal via Digital input or Modbus), results
in the indoor motor turning “ON” and operating at the “HUM” motor speed (Only Applicable
for EC motors).
When there is a request for Indoor Fan (G-input High) along with a request for cooling, heating or
dehumidification, the G-Input becomes lowest priority. This means that in any combination involving
the G-input, the speed associated to Fan Only will never take precedence.
The priority list from Highest to Lowest goes as follows:
1.
Y2 - Request
2.
Y1 - Request
3.
W2 - Request
4.
HUM - Request
5.
G - Request
Note:
The priority list above also describes the operation that takes precedence in the event that there is a
request for all operations or a combination of operations. The controller will NOT energize the compressor
outputs and the heater output simultaneously if configured for AC. The controller WILL energize the
compressor outputs and the heater output simultaneously if configured for HP.
The speed at which the Indoor Fan Operates during Stage 1 (Y1) and Stage 2 (Y2) Cooling Request can
be set directly at the board using the configuration menu settings 4 and 5. All requests are interlocked
with the Indoor Fan and will run the Fan at the respective speed associated with the operation. This means
that a lone call for Stage 1 (Y1) Cooling will automatically run the Indoor Fan at Stage 1 (Y1) Cooling
Speed even without a request for Indoor Fan. This holds true for all request.
2.0 Cooling Operation
AC Systems Request
Active Input
Active Output
Stage 1 Cooling (Fixed Compressor)
Y1
CC1 (Partial Capacity)
Stage 1 Cooling (2 Fixed Compres-sors)
Y1 or Y2
CC1 or CC2 Respectively (Partial Capacity)
Stage 1 Cooling (1 Staged Compressor)
Y1
CC1 (Partial Capacity)
Stage 2 Cooling (2 Fixed Compres-sors)
Y1 + Y2
CC1 + CC2 (Full Capacity)
Stage 2 Cooling (2 Staged Compres-sors) Y1 + Y2
CC1 + CC2 (Full Capacity)
