Enertech VS Series - HWG Pump, Jumpers, Voltage, and Sequence

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Enertech Global IOM, VS/VT Models, Rev A
Section 9: Controls
Hot Water Generator (HWG) Pump Control
Controls check for HWG temperature (T3) and hot
gas (compressor discharge) line (HGT) temperature
(T2). The hot water generator pump is de-energized
when the leaving water temperature (T3) is above
130°F or when the compressor discharge line (T2)
is cooler than leaving water temperature (T3). Also
when the hot gas line temperature (T2) is higher than
220°F, the HWG pump will be de-energized. All of the
issues above will break the circuit of the HWG pump
(via the HWG signal from the lockout board) and will
not lockout the compressor except when T2>220°F.
Units without a HWG also do not have sensors T2 and
T3. The control ignores T2 and T3 and disables Faults
15 and 16, Sensor BAD.
Lockout Board Jumper Selection:
The lockout board includes four jumpers for eld
selection of various board features.
Load/Source HX Temperature Sensing (FS): When
the FS jumper is installed (T1 and T4 monitored, FS
terminals ignored), the board operates in the load
and source heat exchanger temperature sensing
mode, which is the factory setting.
Anti-Freeze (A-FRZ): When the jumper is installed, the
board operates in open loop mode. The setpoint
for the source heat exchanger freeze sensor is 30°F.
When the A-FRZ jumper is removed, the board
operates in the closed loop mode. The setpoint for
the source heat exchanger freeze sensor is 15°F.
Test Mode (TEST): When the TEST jumper is installed,
the board operates in the normal mode. When
the jumper is removed, the board operates in
test mode, which speeds up all delays for easier
troubleshooting. While in the test mode the T1 &
T4 sensors will be checked for the proper location
based on temperature. Sensors are swapped if
T1>T4 in cooling or T1<T4 in heating. This fault will
only show up in the test mode. When service is
complete, the jumper must be re-installed in order to
make sure the unit operates with normal sequencing
delays. While the test jumper is removed, the status
light (bottom green) will remain off.
If the test jumper is not re-installed the control
will revert to normal mode after one (1) hour,
green status light blinking.
Over/Under Voltage Disable (O/V): When the O/V
jumper is installed, the over/under voltage feature is
active. When the jumper is removed, the over/under
voltage feature is disabled. On rare occasions,
variations in voltage will be outside the range of
the over/under voltage feature, which may require
removal of the jumper. However, removal of the
jumper could cause the unit to run under adverse
conditions, and therefore should not be removed
without contacting technical services. An over/
under voltage condition could cause premature
component failure or damage to the unit controls.
Any condition causing this fault must be thoroughly
investigated before taking any action regarding
the jumper removal. Likely causes of an over/
under voltage condition include power company
transformer selection, insufcient entrance wire
sizing, defective breaker panel, incorrect 24VAC
transformer tap (unit control box), or other power-
related issues.
Sequence of Operation
VS Series has a One-Stage compressor with PSC fan
motor or optional ECM fan motor.
VT Series has a Two-Stage compressor with ECM fan
motor (PSC not available).
Timings assume the ASC timer is expired. If the ASC
timer is not expired the fan will start immediately
but the Accessory, compressor, and loop pump
operation do not start until the ASC timer is expired
Heating 1st Stage, (Y1,G) Two-Stage Units
The ECM fan immediately ramps up to 75% of 1st
stage (VT) or 2nd stage (VS) airow (CFM) level
(based on DIP switch settings), the Accessory (A)
terminal output is energized after the random start
timer (10s-20s) expires then rst stage compressor
and the loop pump(s) are energized 10 seconds
after “A”. The ECM fan adjusts to 100% airow
(CFM) level 90 seconds after the “Y1” input. VS units
with a PSC fan start at 100% airow (CFM) level
immediately upon the “G” input.
Heating 2nd Stage, (Y1, Y2, G) VT Units Only
The ECM fan adjusts to 2nd stage airow (CFM) level
(based on DIP switch settings), and the compressor
full load solenoid is energized.