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© 1995-2020 Energy Saving Products Ltd.
© 1995-2020 Energy Saving Products Ltd.
Freeze Stat
The RPM-E series cooling coil comes equipped with an anti-
freeze control mounted on the suction line. This freeze control
serves the purpose of preventing severe icing of the coil in the
event of an undercharge or low load on the coil.
This piece of
equipment must be used at all times. Lack of use of the
freeze-stat will result in RPM-E related warranty issues
being voided.
During start-up, it is acceptable to jumper across
the Freeze-Stat. This will prevent the freeze-stat from shutting
the system off while charging a new system that may be low
on refrigerant. Once charged and running, this jumper must be
removed and the Freeze-Stat connected to the FZ and FZ terminals
on the Printed Circuit Board. Should wiring needs arise in which
the outdoor unit is controlled through another means of wiring,
the Freeze-Stat should be connected in series on the supply side
of the control wiring.
Heat Pumps
Traditionally, SDHV systems have been charged to special
guidelines when used in conjunction with heat pumps. This
charging procedure involved charging the units to normal cooling
capacities and reviewing the operation in heating mode. If head
pressures were found to be impinging on the high head pressure
limits, a small amount of refrigerant was removed to prevent the
unit from shutting down. The cause of high head pressures in
heating mode is due to the disparity in sizes of the indoor and
outdoor coils, along with the lower airflow rates of SDHV systems.
The RPM-E coil can operate at a level that is different from
most other conventional system coils. Typically, superheat levels
are low, 2-4°F of superheat. Adjustment of the valve also differs
somewhat. Rather than having a large effect on the range of
superheat, adjustment of the valve has a larger effect on the
system pressures; superheat maintaining a fairly constant point.
Opening the valve will increase suction pressures and decrease
liquid pressures, while closing the valve will decrease suction
pressures and raise liquid pressures.
Bi-Flow Receiver
The Bi-Flow Receiver is designed
for use with heat pump systems,
up to 5 tons, and with any typical
refrigerants. The receiver allows
refrigerant a location to migrate to
during the heating cycle, minimizing
head pressures. During cooling mode,
the receiver is empty, allowing the full
refrigerant charge to be utilized for
cooling.
The receiver is a horizontal tank with a pair of dip tubes
extending to the bottom of the tank. These two tubes allow for
liquid refrigerant to be drawn from the tank regardless of the
direction of flow. For this reason, the receiver must be mounted
so that the inlet/outlets of the tank come out of the top of the
unit. Mounting brackets are located at the base of the unit for
secure mounting. The receiver is to be located on the liquid line of
the system, anywhere between the indoor and outdoor coils. As
the unit is of a bi-flow design, it does not matter which end faces
towards the indoor coil.
The inlet/outlet ports are constructed of steel and require the
use of a 35-45% Silver Solder and Flux for brazing. The use of
standard copper to copper solders may result in difficulty brazing
and the potential for a failure at the weld. Ensure that the tank is
protected from overheating while brazing and that any remaining
flux is cleaned from the unit. If installing outdoors, ensure that the
receiver is insulated and protected from the elements.
With the introduction of newer, larger heat pumps, this issue
is more likely to be experienced. While some heat pump units
may still be charged in the traditional method, the amount of
refrigerant that is required to be removed for heating mode may
leave the system drastically undercharged for cooling mode. For
this reason it is highly recommended that a Bi-Flow Receiver be
used with heat pump applications.
Charging Cont’d
-5-
-5-
Typical Operating Ranges
Saturated Suction Temperature
38 - 40°F (3 - 4°C)
Suction Line Temperature
42 - 44°F (6 - 7°C)
Superheat
2 - 4°F (1 - 2°C)
Suction Line Pressure
R-22
60 - 72 psig
R-410a
110-124 psig
Liquid Line Pressure
R-22
160-210 psig
R-410a
250-300 psig
Module RPM-E
Refrigerant Module Installation
