Maritime Geothermal EM (DX) 45-55-65, Руководство по установке

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Maritime Geothermal Ltd. 17-Feb-00
if the refrigerant evaporating pressure drops below 20 psig.
Some possible causes for a trip out on low pressure are:
1.Ruptured or broken groundloop coil.
2.Low refrigerant charge.
3.Other refrigerant leak.
2. High pressure control
The second safety control is a high pressure safety limit
which monitors compressor discharge pressure. This device
will not normally trip unless:
1. There is low or no water in the internal tank.
2. Aquastat is set too high. (Above 53°C)
If either of these controls trips it will activate a lock-out relay
which prevents the unit from restarting until power to the con-
trol circuit is broken (by opening the 24v circuit between “R“
and “T“) or the electrical supply to the unit is broken by open-
ing the heat pump breaker and then closing it again. If one of
these controls trips there is a serious problem with the system
and it must be rectified if the unit is to maintain good service.
Electrical
The NORDIC® unit is supplied with an opening for 19
mm conduit nipple on the right side of the unit. An additional
13 mm knock-out is also supplied to accommodate accesso-
ries which may be attached to the heat pump's relays (such as
circulator pumps etc.). Above the accessory knock-out is an-
other 9 mm hole for the thermostat wire which controls the
circulator pump. A wiring diagram is located on the electrical
box cover for quick reference and although the connections to
be made are quite simple, Maritime Geothermal Ltd. recom-
mends that a properly qualified electrician be retained to
make the connections and wire the thermostat.
Starting the Heat Pump
BEFORE starting the heat pump the following areas
should be rechecked to assure proper operation.
1.
Check all high voltage field wiring and electrical connec-
tions inside the control box for good connection.
2. Turn on the main power switch. The Ranco® 2-stage aq-
uastat stage1 setpoint is set to 110°F with a 10°F differ-
ential from the factory. Stage2 of the aquastat is factory
set at 100°F with a 5°F differential. This means that the
unit will cycle on stage1 and stage2 when first powered
up.
3. Turn on the water supply to the hot water lines and check
all plumbing for leaks.
4. Check the hot water tank to be sure it is filled with water
before energizing the circuit. Slightly open the pressure
relief valve on the top of the hot water tank to make sure
that all air is out of the system and the circulator pump is
flooded with water.
5. Vacuum out any dust and debris that may have collected
in the unit during installation.
6. Make sure the proper time-delay fuse or breaker has been
installed in the electrical panel.
7. Have the following tools on hand and know how to use
them.
•
A refrigeration gauge set.
•
An electronic or other accurate thermometer.
•
An amprobe.
1. Connect your refrigeration gauge set.
2. Turn on the power to activate the system. The Ranco aq-
uastat will display the temperature in the tank and if be-
low the setpoint – “S1” and “S2” will be displayed in the
LCD window and the compressor will start.
3. Observe the readings on the high and low pressure gauge
set. With an initial earth temperature of 7° to 10° C the
suction pressure (blue gauge) should be approximately
315 to 400 kPa while the head or discharge pressure (red
gauge) should be in the area of 1350 to 1900 kPa. Record
this information on the warranty test card.
4. The temperature on the aquastat should show a steady
rise as the internal distribution tank warms up. As the
temperature rises above the electric back-up setting, “S2”
will disapear from the display and only the heat pump
will be operating.
5. If you wish to operate the unit without the electric back-
up coming on then switch the internal electric heat
breaker off.
6. At the electrical disconnect switch place the amprobe
jaws around the supply wires and record the current in
each conductor and record this current.
7. When the tank comes up to temperature you can open
any valves on the hot water supply lines and the unit is
ready to operate.
General Maintenance
As with any piece of equipment there will eventually be
some maintenance to be done on the heat pump however a
EMDX heat pump is relatively maintenance free and only one
item will need attention as follows:
⇒
Check contactors for burned or pitted points.
Theory of Operation
The EMDX heat pump utilizes a typical vapor compres-
sion refrigeration cycle similar to many other common appli-
ances. The only difference between a
Direct Expansion heat
pump and a conventional geothermal unit is the fact that the
DX unit has it’s heat exchanger embedded in the ground. The
EM machine also incorporates the condenser coil directly in-
side the internal hot water buffer tank
Due to some engineering obstacles involved with remote
parallel evaporators some special equipment and techniques
which are described below are required to allow such a sys-
tem to work effectively. Some text below may also describe a
heat / cool system. If your system is heat only or heat and hot
water then skip over the cooling description sections.
4-Ton System Description Heating Mode
All NORDIC® EMDX systems utilize multiple earth
loops to transfer heat to and from the ground. One loop per
ton of capacity is normally required and during the heating
mode all the loops are active.
Liquid refrigerant passes from the air handler section
through the bi-flow filter-drier and through the cooling TX
valve which is fully open by virtue of it’s equalizer line being