40
Enertech Global
IOM, BS/BT Models
33
Enertech Global
YT Models, 08 December 2014A
Features
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.
Lockout Board
The Lockout Board controls the inputs to the
unit as well as outputs for current mode,
faults, and diagnostics. A status LED and
different combination of four LEDs for each
fault are provided for diagnostics.
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 five 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 optimum space conditioning
performance, 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.
Humidifier/Dehumidification Connections
Connections for a humidistat are provided for
some models, which automatically engage
the fan when the humidistat contact closes.
In addition, a field connection is provided at
the terminal strip for external control of the
On Demand Dehumidification (ODD) feature
of the variable speed ECM fan motor, which
automatically lowers the fan speed when the
space humidity is higher than the humidistat
set point. Either connection may be used with
a thermostat that includes humidifier/
dehumidification outputs.
Safety
The lockout board receives feedback signals
for high pressure, low pressure, water flow,
and hot gas temperature faults. Upon a
continuous 30-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
Section 9: Controls
Features
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.
Lockout Board
The Lockout Board controls the inputs to the unit
as well as outputs for current mode, faults, and
diagnostics. A status LED and different combination
of four LEDs for each fault are provided for
diagnostics.
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 five 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
optimum space conditioning performance, 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.
Humidifier/Dehumidification Connections
Connections for a humidistat are provided for some
models, which automatically engage the fan when
the humidistat contact closes.
In addition, a field connection is provided at the
terminal strip for external control of the On Demand
Dehumidification (ODD) feature of the variable
speed ECM fan motor, which automatically lowers
the fan speed when the space humidity is higher
than the humidistat set point. Either connection may
be used with a thermostat that includes humidifier/
dehumidification outputs.
Safety
The lockout board receives feedback signals for
high pressure, low pressure, water flow, and hot gas
temperature faults. Upon a continuous 30 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