21
HP IOM, Rev. B
Enertech Global
Enertech Global geothermal heat pump controls leverage a
modular approach for controlling heat pump operation. The
control system uses a combination of printed circuit boards,
depending upon the features equipped in a particular unit.
This approach simplifies installation and troubleshooting, and
eliminates features that are not applicable for some units.
The Lockout Board controls the inputs to the unit as well as
outputs for current mode, faults, and diagnostics. A status
LED and different combinations of four LEDs for each fault are
provided for diagnostics. The Lockout Board terminal “L” puts
out the number of corresponding 24VAC pulses to indicate the
Lockout condition on the Thermostat (if equipped and wired).
Startup/Random Start
The unit will not operate until all the inputs and safety controls
are checked for normal conditions. A ten to twenty second
random start delay is added at power up and whenever a Y1
call is received. This avoids multiple units from being energized
at the same time after events such as power loss or brown
outs�
Short Cycle Protection
A built-in 8 minute anti-short cycle (ASC) timer provides short
cycle protection ensuring that the compressor isn’t damaged
due to rapid cycling�
Component Sequencing Delays
Components are sequenced and delayed for reduction in
surge current, and to reduce startup noise of the system. The
accessory terminal on the Lockout Board engages 10 seconds
prior to the compressor. This provides increased time for items
such as external pumps to provide adequate water flow prior
to the system starting.
Test Mode
The Lockout Board allows the technician to shorten timing
delays for faster diagnostics by placing the DIP switch ‘TEST’
switch in the ON position (See ‘Settings’ section). It should be
moved back to OFF for normal operation after testing. The
status LED will not be illuminated during the TEST mode.
Water Solenoid Valve Connections
If equipped, the accessory terminal strip provides a
field connection for a valve with an end switch, which is
recommended (see wiring diagram). An accessory relay
terminal, “A”, can be used for solenoid valves without an
end switch. This terminal is energized 10 seconds before the
compressor contactor. A valve without an end switch could
cause a water hammer effect and is not recommended.
Safety
The lockout board receives feedback signals for high pressure,
low pressure, load heat exchanger temperature, and source
heat exchanger temperature. Upon a continuous 10-second
measurement of all faults (except the high pressure) the
compressor operation is suspended. The high pressure fault is
tripped instantly. The different combination of LED(s) indicate
each temporary fault. Once the unit is locked out (see fault
retry below), the Lockout Board outputs a number of 24VAC
pulses equal to the numbered fault code.
Low Pressure-LP
If the low pressure switch is open continuously for 30 seconds,
the compressor operation will be interrupted, and the control
will go into fault retry mode. At startup, the low pressure
switch is not monitored for 30 seconds to avoid nuisance
faults. (If the low pressure switch is open before startup then
the unit will not start upon receiving an Y1 call and will lock
out instead.)
High Pressure (HP)
If the high pressure switch opens, the compressor operation
will be interrupted, and the control will go into fault retry
mode. There is no delay between the time the switch opens
and the board entering into fault retry mode. There is also no
delay of switch monitoring at startup. (If the high pressure
switch is open before startup then the unit will not start upon
receiving an Y1 call and will lock out instead.)
Section 7: Controls
A
CC
C
R
Y
L
O
O
1
CC
G1
CC
G
HWG
R_2 R_1 C_2 C_1
HP1
HP2
LP1
LP2
FS1
FS2
CO1
CO2
T3
T2
T1
FS
TEST
O/V
A-FRZ
T4
W1
W2
Y2
G
STATUS
Features
