Hi-Velocity RPM-E-70 Manuale di installazione - Pagina 4

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Hi-Velocity RPM-E-70 Manuale di installazione

Pipe Sizing

When sizing refrigerant piping,

follow the outdoor unit

manufacturer's recommendations.

Piping the RPM-E

Only refrigerant grade pipe and fittings are to be used with

Hi-Velocity Systems. Plumbing fittings may contain wax or other

contaminants which are detrimental to the proper operation of

the system. Insulate the suction line with 3/8" (9.53mm) insulation

such as Armaflex. In high heat areas, 1/2" (12.7mm) insulation

may be needed. If the lines are run in an area where temperatures

could exceed 120°F (49°C) or runs longer than 50' (15.24m), then

the liquid line may need to be insulated as well. Support the pipe

every 5 feet (1.52m), or whatever local code states.

Run the pipes in the most direct route possible, taking into

account structural integrity and building details. If the evaporator

is located above the condenser, slope any horizontal runs toward

the condenser. If the condenser is located above the evaporator,

a P-trap must be installed at the bottom of the vertical riser. For

long vertical risers, additional P-traps must be installed for every

twenty feet (6m). For lines running over 50' (15m), a suction line

accumulator must be installed. Lines running over 100' (30m) are

not recommended. All lines should be piped so as not to restrict

access to the front panels, filter section, or electrical enclosure.

Brazing & Pressure Testing

The RPM-E comes pre-piped with the coil assembly. With the

RPM-E, the Liquid and Suction lines are the only brazing that need

to be done at the fan coil. For charging and brazing, remove the

front access panel of the RPM-E (Fig. RPM-06). With the access

panel removed, the coil assembly will be accessible. Wet rag the

liquid and suction line (or use a heat dissipating paste) to ensure

no overheating occurs to the pre-piped coil assembly. Excess heat

may damage the RPM-E components.

Fig. RPM-06 - Remove Front Access Panel

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Once the system has been brazed it must be pressure tested.

Pressure testing must be done with nitrogen and not refrigerant.

Typically, pressures are tested to the maximum operating pressure

that the system will see. Allow the system to hold the nitrogen

charge for at least 15 minutes to ensure there are no leaks. Check

with local codes for proper testing procedures.

After the piping is installed and all components have been

brazed together, a vacuum pump must be used to evacuate the

system from both the low and high side to 1500 microns (200

pa). Add pressure to the system to bring the pressure above zero

psig. After allowing the refrigerant to absorb moisture, repeat the

above procedure. Evacuate the system to 500 microns (67 pa) on

the second evacuation, and ensure that the system holds at the

vacuum pressure. If not, check for leaks and evacuate again. At

this point open service valves on pre-charged condensing units,

and add refrigerant to the system if necessary.

The use of an electronic leak detector is recommended, as it is

more sensitive to small leaks under the low pressures.

Once the system has been determined clean and ready for

charging, refrigerant can be added. The service valves on the

condenser must be open at this point. Never leave the system

unattended when charging. With the system running, slowly

add refrigerant. The typical operating point of an RPM-E coil is

that of a saturated suction temperature of 38-40°F (3-4°C) and a

suction line temperature of 42-44°F (6-7°C). In order to prevent

overcharging during this stage, refrigerant should be added in

steps. This will allow time for the system to settle and prevent

'overshooting' the ideal charge. Condenser pressures and

temperatures remain similar to those in a conventional forced air

system. It is recommended that the coil be charged on a high load

day at the compressor's highest speed.

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.

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Module RPM-E

Refrigerant Module Installation

Evacuating

Charging