Maritime Geothermal EMWT-65-HACW-P-1T, Инструкция по установке и обслуживанию

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Page 6 000662MAN-03 01 MAR 2012
tank temperature rate of change is reduced when only
Stage 1 is active.
•
Prolonged Stage 1 runtime leads to increased overall effi-
ciency as Stage 1 has a higher COP than Stage 2.
•
Reduced number of compressor starts.
The settings may be changed as desired; however Stage 1
setpoint for heating should not exceed 120°F (49°C) ; Stage 1
cooling setpoint should not be set below 43°F (6°C). Exceeding
these setpoint limits will cause the heat pump operating pres-
sures to approach the safety control settings, possibly causing
nuisance shut downs.
If fan coils are being heated, it may be required to in-
crease the heating setpoints by 10°F (6°C) in order to obtain
the required heating capacity.
SAFETY CONTROLS
The heat pump has two built in safety controls which are
designed to protect the unit from situations which could damage
it should the operation of the refrigeration circuit fall outside the
allowable operating range.
A. Low Pressure Control
The low pressure control monitors the compressor suction
pressure and will shut the compressor down if the refrigerant
evaporating pressure becomes too low, risking the danger of
freezing conditions in the evaporator.
There are (3) main reasons why this control would activate
in response to the operating conditions of the unit while operat-
ing in heating mode:
1. Low or no Outdoor loop flow.
2. Low Outdoor loop entering liquid temperature.
3. Dirty or fouled Outdoor loop heat exchanger.
B. High Pressure Control
The high pressure safety control monitors the compressor
discharge pressure and will shut the compressor down if the
condensing pressure becomes too high.
There are (3) main reasons why this control would activate
in response to the operating conditions of the unit while operat-
ing in heating mode:
1. Low or no Hot Indoor loop flow.
2. High Hot Indoor loop entering liquid temperature.
3. Dirty or fouled Hot Indoor loop heat exchanger.
The unit contains a control board that monitors the safe-
ty controls and operates the compressor accordingly. The low
pressure control is connected to LP1 and LP2. The high pres-
sure control is connected to HP1 and HP2.
The control board also has provisions for a flow switch.
The flow switch is unused from the factory and a jumper wire is
placed across the FLOW SWITCH terminals. If a flow switch is
desired, the jumper can be removed and the two leads from the
flow switch can be connected to the FLOW SWITCH terminals
on the safety board. The flow switch is ignored for 30 seconds
on compressor startup to allow time for flow to be established.
The high and low pressure controls are monitored at all times,
the compressor will not be able to start if either of them has a
fault.
The control board has an on-board LED and a FAULT
pin with a 24VAC output. An external indicator or relay can be
connected across the FAULT pin and ground if external signal-
ing is desired. Should a fault occur, the LED will flash the code
of the fault condition while the safety control in question is open
The codes are shown in TABLE 3. The control board will lock
out the compressor for five minutes when a fault occurs. Three
retries per fault condition are allowed within a 60 minute period.
If the fault condition occurs a fourth time the control board will
permanently lock out the compressor and energize the FAULT
pin. This can only be reset by powering down the unit. The
LED will flash the fault code until the unit is reset.
If the control board enters permanent lockout mode there
is a serious problem with the system and it must be rectified if
the unit is to maintain good service.
WARINING: If the the heat pump is permanently
locking out on the LOW pressure control, repeat-
ed resetting of the unit could cause the heat
exchanger to freeze and rupture destroying the
heat pump and voiding the warranty.
INDICATOR LIGHTS
The EMWT-Series unit has three indicator lights on the
side of the electrical box. They are described in TABLE 4.
TABLE 3 - Control Board Fault Codes
Fault Code
High Pressure 1
Low Pressure 2
Flow 3
TABLE 2 - Typical Aquastat Settings
HEATING AQUASTAT
Stage 1 Stage 2
Item ° F ° C °F °C
Setpoint 105 41 100 38
Delta 8 4 8 4
Activation * 97 37 92 34
COOLING AQUASTAT
Stage 1
Item ° F ° C °F °C
Delta 8 4 8 4
Activation * 53 11 58 14
*Activation is indirectly set by the Setpoint and Delta
values
Stage 2
Setpoint 45 7 50 10
TABLE 4 - Indicator Lights
Colour Indicates
Green Compressor ON
Yellow Electric Elements ON
Red Trouble (Locked out)
!