Maritime Geothermal EMWT-65-HACW-P-1T, Installation And Service Manual

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01 MAR 2012 Page 5 000662MAN-03
UNIT DESCRIPTION
The EMWT-Series unit is a high efficiency R410a refriger-
ant two-stage geothermal heat pump with a hot and cold buffer
tank, zone circulators, expansion tank, valves and gauges, and
controls. It is a compact stand alone modular system that
greatly reduces installation time and space.
The unit has several key features that are described in the
specifications document for the particular heat pump. Please
request a copy if desired or visit
www.nordicghp.com
UNPACKING THE UNIT
When the heat pump reaches its destination it should be
unpacked to determine if any damage has occurred during
shipment. Any visible damage should be noted on the carrier's
freight bill and a suitable claim filed at once.
The heat pump is well constructed and every effort has been
made to ensure that it will arrive intact, however it is in the
customer's best interest to examine the unit thoroughly when it
arrives.
OPTIMUM PLACEMENT
The placement of a hydronic unit has negligible effects on
the operation of the system. For ground water systems, the unit
can be placed near the well water system, ground loop system
units can be place near where the header pipes enter the struc-
ture to keep the ground loop piping, heat pump and circulator
pump module in one location. The hydronic layout may make a
particular location ideal for the unit installation.
If possible the access panels should remain clear of
obstruction for a distance of two feet to facilitate servicing and
general maintenance.
Raising the heat pump off the floor a few inches is
generally a good practice since this will prevent rusting of the
bottom panel of the unit. We recommend that the heat pump be
placed on a piece of 2'' Styrofoam covered with 1/4'' plywood.
The Styrofoam will smooth out any irregularities in the cement
floor while the plywood will distribute the weight of the unit
evenly over the Styrofoam. This process will also deaden the
compressor noise emitted from the bottom of the cabinet.
ELECTRICAL PROVISIONS
The heat pump has a concentric 1.093” / 0.875” knockout
for power supply connection to the electrical box. There are
also two other 0.875” knockouts: one for connections to the in-
door circulator; the other for connections to the circulator pump
module for ground loop applications. There are three 1/2” open-
ings with plastic grommets (grommet hole is 3/8”) in the upper
section of the electrical box for connections to the controls.
A schematic diagram and electrical box layout diagram
can be found inside the electrical box cover for quick reference
on the connections required. The electrical box diagram also
contains information about the size of wire for the connections,
as well as the recommended breaker size.
A properly qualified electrician should be retained to make
the connections to the heat pump and associated controls. The
connections to the heat pump
MUST conform to local codes.
CIRCULATOR PUMP MODULE WIRING
(GROUND LOOP ONLY)
The heat pump has provisions for connecting the circulator
pump module so that the pumps will be turned on whenever the
compressor operates. Connect the circulator pump module to
the appropriate two terminals of the terminal strip marked
OUTDOOR CIRCULATORS in the heat pump, as per the volt-
age of the circulator pump module. Ensure that the total current
draw of all circulators connected to the terminal strip does not
exceed the value indicated on the label in the heat pump electri-
cal box. Refer to the electrical box drawing on the electrical
box cover for more information.
CONTROL REQUIREMENTS
The heat pump comes equipped with a two-stage heating
aquastat and a two stage cooling aquastat. The stages are S1
= Stage 1 compressor, and S2 = Stage 2 compressor, as well
as auxiliary heat on a 0-2 hour timer. The EMWT unit operation
is self sufficient, the only control signals required are to turn on
the Heating and Cooling Zone Circulator(s) located inside the
unit
The electrical box diagram on the electrical box cover pro-
vides a description of the signal connections in the heat pump.
They are also listed in
TABLE 1 below.
The Heating Zone circulator is activated by connecting R
and HZ together via dry contacts. The Cooling Zone circulator
is activated by connecting R and CZ together via dry contacts.
Dry contacts are used for all heat pump connections to ensure
that the heat pump control signals remain isolated from the rest
of the system. The PR terminals are used to configure the prior-
ity of the unit. The unit is shipped with a jumper wire connected
between the PR terminals to select cooling mode as the priority
mode, remove the jumper to select heating as the priority mode.
Drawing 000665CDG depicts a heating/ cooling wiring
diagram. These drawings represent a basic system, in which
heating is the default mode and cooling has priority. It is rec-
ommended that the system be designed by a qualified system
designer to ensure proper functionality.
TABLE 2 shows typical settings for the aquastats. With
these settings, Stage 1 will activate when the tank temperature
reaches the activation point. If the load is too great, the tank
temperature will continue to drop when heating (rise when cool-
ing) until Stage 2 is activated. As the tank temperature stops
dropping and begins to increase when heating (decrease when
cooling) , Stage 2 will turn off before Stage 1, rather than at the
same time as Stage 1. There are three main advantages to this:
•
Less aquastat probe lag leading to reduced overshoot as the
TABLE 1 - Control Signal Description
Signal Description
C 24VAC Common (Ground)
R 24VAC Hot
HZ Heating Zone Circulator
CZ Cooling Zone Circulator
PR Priority Select
PR Priority Select
Installation Information