Hi-Velocity RPM-E-70 Посібник з монтажу - Сторінка 5

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Charging Cont'd

Most system start ups require only an adjustment to the

refrigerant level of the system. Should further refinement be

required, the TXV may be adjusted. A clockwise turn of the

superheat valve (the direction in which the cap is screwed on)

will result in a closing of the valve while a counterclockwise

turn (the direction in which the cap was unscrewed) will result

in opening of the valve. Always note system conditions before

adjusting the valve and allow 5 minutes for the system to settle

before making any further adjustments. Never adjust the TXV

more than one quarter turn at a time.

The RPM-E coil can operate at a level that is different from

most other conventional system coils. Typically, superheat level

are low, two to four degrees 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.

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 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.

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Module RPM Refrigerant Module Installation (RPM-E) (4/5)

Refrigerant Module Installation (RPM-E) (4/5)

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.

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 X1 and X2 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.

Module RPM