30
Compressor Start Delay
The control is equipped with a compressor start delay
to prevent short-cycling of the compressor. The con-
trol will not energize a compressor unless the
compressor has been off for at least 3 minutes. When
this situation arises, the display shall read “Comp Start
Delay” until the timer clears and the compressor starts.
Minimum Run Time
To ensure proper operation of the compressor and
longest life, the control has a minimum run time for the
compressor of 3 minutes. If the setpoint is reached
within 3 minutes, the compressor will continue to run
for 3 minutes unless (1) the high pressure switch trips,
(2) the water pressure switch trips, (3) the high tem-
perature limit is reached, or (4) the user selects “OFF”
mode.
Defrost Operation
The control is equipped with several defrost algorithms
depending on the configuration of the unit (HEAT
ONLY, POWER DEFROST or HEAT/COOL).
On HEAT ONLY models, the control initiates a defrost
cycle when the coil temperature falls to the “Defrost
Temp” setpoint (24F default) established in the
Installer/Service sub-menu. The compressor will shut
off, but the fan will continue to operate to pull warmer
air across the coil in an effort to defrost the coil. When
the control sees a rise in the coil sensor temperature
equal to “Defrost Temp” + “Defrost Deadband” (10F
default) or after 15 minutes have passed, the unit will
exit the defrost cycle and will return to normal heating
operation based on the current water temperature and
setpoint temperature.
On POWER DEFROST models, the control initiates a
defrost cycle when the coil temperature falls to the
“Defrost Temp” setpoint (35F default) established in
the Installer/Service sub-menu. The compressor will
continue to operate (as well as the fan) and a solenoid
valve will open allowing a portion of the hot refrigerant
gas to bypass the heat exchanger and be directed
back to the coil to warm the coil for defrost. When the
control see a rise in the coil temperature equal to the
“Def Terminate” value established in the
Installer/Service sub-menu (50F default), the solenoid
valve will shut and the unit will return to normal heating
operation based on the current water temperature and
setpoint temperature.
On HEAT/COOL models, the control initiates a defrost
cycle based on a programmed algorithm involving cur-
rent and baseline ambient temperatures, and current
and baseline coil temperatures when the coil temper-
ature drops below the “Defrost Temp” set in the
Installer/Service sub-menu. Factory default is 35F.
The control shuts off the fan and activates the revers-
ing valve so the hot refrigerant gas is directed to the
coil to defrost the coil. When the coil sensor sees tem-
peratures above the “Def Terminate” value set in the
Installer/Service sub-menu, the unit returns to normal
operation based on the current water temperature and
setpoint temperature.
3-Way Valve Control
The control is equipped to operate system 3-way
valves. The control will set the 3-way valves to the
state requested when there is an active thermostat
demand for spa heat, pool heat or pool cool AND when
Pump operation is enabled through the control. This
takes priority over positions requested by Pump
Schedule operations. If the control also operates the
pump, the pump will shut off for 30 seconds before the
valves change state so as to not have to fight pump
head pressure during change of position. During this
change, the display will show “Valve Chng Delay”.
The 3-way valves are field installed to the #38-40 &
#41-43 terminals on the terminal strip inside the junc-
tion box of the unit. The initialization of the 3-way
valves is set in the Installer/Service sub-menu.
If the water pressure switch (or water flow switch) is
closed when the control needs to change the 3-way
valve position, the control displays “WPS Closed” and
waits indefinitely with the pump and compressor off
until the water pressure switch (water flow switch)
opens. After it senses the open switch, the control
switches the 3-way valves and resumes normal oper-
ation.
If no thermostatic demand is requesting operation and
the pump is being run from scheduled pump periods,
the control sets the 3-way valves to the states request-
ed in the pump period mode schedule.
When there is no demand for pump output because of
manually selected OFF mode, no thermostat demand
or no scheduled pump period, the control leaves the 3-
way valves in their last commanded state. Valve
outputs will not change until there is an active request
for them to be in a different state.
NOTE:
On Power Defrost and Heat/Cool models
the initial defrost after power ON is a "sacrificial"
defrost where the coil might freeze up more than
expected. The control is learning the parameters of
the installation to establish clear coil temperature
conditions for future defrost operation.
