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Water to Water Source Heat Pumps
IM 1072-1
Control
Compressor Control Module Functional
Operation – 208-230/60/3, Unit Sizes 120,
150, 180, 240 and 300
Power:
For proper operation there must always be 18 to 30 volts AC
present at the R and C terminals.
Time Delays:
1.
Anti-short cycle:
provides the compressor with short
cycle protection for a selectable time of 10 seconds (for
servicing only) or 5 minutes (normal operationalsetting).
This feature is enabled upon power loss to the circuit
board, loss of the Y signal, or the opening of a switch
connected to the HPS or LPS terminals. If the selecto
shunt is not in place, the circuit will default to a 5 minute
anti short-cycle delay.
2. Delay on make:
Delays the turning on of the compres
-
sor contactor for a selectable time of 3 or 6 seconds
every time the Y signal coalls. If the selector shunit is not
in place, the circuit will default to a 6 second delay on
make.
3. Low Pressure Bypass:
Allows time for the low side
pressure to build up enough pressure at start up for the 60
psig low pressure switch to close. The circuit will offer a
selectable timing range of 90, 120, 180, or 300 seconds.
This time delay will start upon a Y call from the thermo
-
stat. Should the 60 psig low pressure switch still be open
after the selected delay expires, the compressor will de-
energize and the alarm will energize. This will be defined
as an LPS fault, (factory set for 90 seconds). If neces
-
sary to increase the delay, select the smallest amount of
bypass time delay that allows the compressor to start and
operate.
Note:
The 60 psig low pressure switch is jumpered out in low
temperature closed loop system applications using
antifreeze solution.
Also note tht the 35 psig low pressure switch is con-
nected in series with the high pressure switch to the
HPS terminals and is never bypassed.
Operation Of The HPS Terminals
Switches connected to the HPS terminals are connected in
series with the Y signal through the circuit board. These switches
are also connected in series witht the T1 output in order to
provide an immediate response if a switch were to open. If a
switch conncecte to the HPS terminal should open, the status
LED will blink once.
Operation Of The LPS Terminals
The 60 psig low pressure switch (brown leads) is connected
to the LPS terminals in series with the Y signal through the
circuit board. The 60 psig low pressure switch is connected in
series with the Y signal to the processor only. This will allow
the control to monitor the low pressure switch status and initi
-
ate the bypass delay. If the 60 psig low pressure switch should
open, the status LED will blink twice.
Normal Cycle
A normal cycle will begin with 24 VAC applied to the R and
C terminals on the circuit board. Once the control is powered up,
the processor will read the Y signal to determine if it is calling.
If it is calling and the switches connected to the HPS terminals
are closed, the delay on make and low pressure bypass timers
will initiate.
If a switch connected to the HPS terminals is open, the con
-
trol will enter the lockout mode. After the delay on make time
expires, the compressor contactor will energize. It will remain
energized as the low pressure bypass timer counts down.
If the 60 psig low pressure switch is closed after the timer
expires, the compressor will remain energized. If it is still open,
the control will enter the lockout mode.
If power is lost, or the Y signal is removed, or an HPS or LPS
terminal switch fault is detected while the compressor contac
-
tor is energized, the unit will initiate the anti short-cycle delay.
Alarm/Lockout
The alarm terminal will output the R signal and will only be
energized as a result of an HPS or LPS fault. An HPS fault is de
-
fined as the opening of a switch connected to the HPS terminals
for any amount of time. An LPS fault is defined as the 60 psig
low pressure switch open after the bypass time. If any of these
conditions are true, the unit will de-energize the compressor and
energize the alarm. This will be defined as a lockout condition.
To reset a lockout condition, the pressure fault must be corrected
and the Y signal from the thermostat must be cycled.
Figure 9: Compressor control module functional operation
LPS
Y
HPS
T1
T
C
R
X
P
10
P
11
P
12
10
S
E
C
5
M
IN
P
7
P
8
P
9
3
S
E
C
6
S
E
C
P
5
P
4
P
3
P
2
P
1
30
0
18
0
12
0
90
LP
S
B
Y
P
A
S
S
S
E
C
O
N
D
S
D
O
M
A
S
C
R
LE
D
:
O
FF
=
N
O
Y
S
IG
N
A
L
P
R
E
S
E
N
T
O
N
=
Y
S
IG
N
A
L
P
R
E
S
E
N
T
1
B
LIN
K
=
FA
U
LT
O
N
H
P
S
TE
R
M
IN
A
LS
2
B
LIN
K
S
=
FA
U
LT
O
N
LP
S
TE
R
M
IN
A
LS
LP
R
-A
L1
70
1
To prevent both compressors from
starting at the same time (resulting in
extremely high inrush current): The
delay on make timer for CCM1 is factory
set to 3 seconds. The delay on make timer
for CCM2 is factory set to 6 seconds.
Status LED
Disconnect power to
WW* unit before moving
jumpers!
Use lowest LPS bypass time
setting which allow unit to start and
operate. Do not set the jumper any
higher than necessary.
10 SEC jumper is for servicing unit only.
Do not operate unit unattended with
jumper in the 10 second position!
