Hi-Velocity RPM-E 50 Panduan Instalasi - Halaman 5

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Charging Cont'd

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.

Typical Operating Ranges

Saturated Suction Temperature

Suction Line Temperature

Superheat

Suction Line Pressure

Liquid Line Pressure

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.

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.

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

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.

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38 - 40°F (3 - 4°C)

42 - 44°F (6 - 7°C)

2 - 4°F (1 - 2°C)

R-22

60 - 72 psig

R-410a

110-124 psig

R-22

160-210 psig

R-410a

250-300 psig

allows

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.

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.

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.

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Module RPM-E

Refrigerant Module Installation

Freeze Stat

This piece of