
MORTEXPRODUCTSINCFORTWORTH,TX76106Page11
When the compressor lockout switch is used the switch is
secured to the water coil. The two yellow wires are connected
to the CLin and the CLout terminals. When the temperature of
the water coil reaches 38°F the switch opens which de-
energizes the CC terminal on the control board. When the
water temperature has risen above 42°F the compressor
lockout switch will close. The control will send 24 VAC to the
CC terminal on the control board.
** If the compressor lockout switch is not used place a jumper
wire on CLin and CLout to get 24 VAC from the Y terminal to
the CC terminal. The indoor blower will not energize in the
cooling mode until the CC terminal has 24 VAC at the
terminal.
AQ – The aquastat switch is placed on the hot water line
exiting side of the air handler coil. The aquastat is connected
to the R terminal and the AQ terminal on the control board.
The AQ jumper pin shown in Figures 1 and 2 must be in the
ON position to use this feature.
When there is a call for heat – 24 VAC on the W terminal and
the water line temperature reaches the aquastat switch setting
the switch will close sending 24 VAC to the AQ terminal
turning on the blower motor. The blower motor will not
energize until the aquastat switch is closed. When the call for
heat has been removed the indoor blower will de-energize
after the selected OFF delay.
VALVE – There are two terminals used to power a 24 VAC
zone valve or solenoid valve. The terminal closest to the 24V
COM terminals is a 24V common terminal to the valve. See
Figures 1 and 2. The other terminal is the 24 VAC output to
the valve. When there are 24 VAC to the W terminal the
control board will send 24 VAC to the valve terminals. The
VALVE terminals de-energize when the 24 VAC is removed
from the W terminal.
BOILER - There are two terminals that are connected to a
switch. The terminals do not output any voltage. They are dry
contacts. The BOILER switch is designed to be connected to
the “T” “T” terminals on a boiler aquastat to energize the
boiler when the control board has a call for heat (24 VAC on
W).
G – When 24 VAC is placed on the G terminal the control will
energize the indoor blower on the FAN CIR speed terminal
with NO delay. When the 24 VAC signal has been removed
from the G terminal, the indoor blower will de-energize with
NO delay.
If there is a call for heat (24 VAC on the W Terminal) while
24 VAC is present on the G terminal, the control will energize
the pump, valve and boiler. The indoor fan motor will de-
energize. The indoor fan motor will be energized on the LO
speed terminal after the selected ON delay. When the call for
heat has been removed the control will de-energize the valve,
pump and boiler. The indoor fan motor will de-energize after
the selected OFF delay then, the indoor fan motor will switch
to the FAN CIR speed terminal.
W - When 24 VAC is present on the W Terminal the control
will energize the pump, valve and boiler. The indoor fan will
start on the LO speed terminal after the selected ON delay.
When the call for heat has been removed the control will de-
energize the valve, pump and boiler. The indoor fan motor
will de-energize after the selected OFF delay.
FR – The FR terminal energizes the control board freeze
protection. The freeze protection switch is secured to the water
coil. The two white wires are connected to the R terminal and
to the FR terminal on the control board. When the temperature
of the coil is below 38°F the freeze protection switch closes it
sends 24 VAC to the FR terminal. The control will energize
the pump, valve and boiler. The control will not energize the
indoor fan motor even when there is a call for heat with 24
VAC on the W terminal. When the water temperature has
risen above 42°F the freeze protection switch will open. The
control will de-energize the pump, valve and boiler, providing
there is not a call for heat. If there is a call for heat at the time
FR is de-energized the pump, valve and boiler will remain ON
and the control will start the indoor fan motor on the LO speed
terminal after the selected ON delay.
RH/W2 – RH is only used for reheat mode with a thermostat
that has the reheat function.
BY – Bypass terminal is used when the heating and domestic
hot water system are managed with the same tankless hot
water system. The domestic water line has a normally open
flow switch that is connected to the R and the BY terminals on
the control board. When the domestic water flow switch
detects the flow of water the switch closes sending 24 VAC to
the BY terminal. The control will de-energize the PUMP,
VALVE, BOILER and the Indoor Fan Motor. When the
domestic water flow has stopped the domestic water flow
switch will open and the PUMP, VALVE and BOILER will
resume normal operation. The indoor fan will be energized
after the selected ON delay.
Y– When 24 VAC is placed on the Y terminal the control will
energize the indoor blower on the HI speed terminal after the
selected ON delay. When the 24 VAC signal has been
removed from the Y terminal, the indoor blower will de-
energize after the selected OFF delay.
If there is 24 VAC on the G Terminal while 24 VAC is present
on the Y terminal, the control will energize the indoor fan
motor on the HI speed terminal. When the 24 VAC has been
removed the control will switch the indoor fan motor back to
the FAN CIR speed terminal. When 24 VAC is removed from
the G terminal the indoor blower motor will de-energize with
NO delay.
DHM – Dehumidification mode can be used with any
thermostat that has dehumidification terminal. The
dehumidification terminal must sent 24 VAC to the DHM
terminal on the control board to put the control in
dehumidification mode.
On Startup when 24 VAC is present on the Y terminal the
control will pass 24 VAC to the CLin, then to the CLout
terminal, then to the CC terminal to energize the compressor
contactor. If the DHM terminal has 24 VAC present the
control will energize the indoor blower motor on the MED
speed terminal after the selected ON delay.
If the control has the indoor blower motor operating on the HI
speed terminal when 24 VAC is placed on the DHM terminal
the control will switch to the MED speed terminal with NO
delays.
If the control has the indoor blower motor operating on the
MED speed terminal when 24 VAC is removed from the
DHM terminal the control will switch to the HI speed terminal
with NO delays.