Bosch SM024 Spécifications télécharger pdf (Page 12)

12 | Refrigerant Lines SM AH Series Heat Pump

SM AH Series Heat Pump873392084 (2013/11) Subject to change without prior notice

• Oil is continually being circulated with the

refrigerant so, oil return to the compressor is

always a consideration in line sizing. Suction

lines on split system heat pumps are also hot

gas lines in the heating mode, but are treated

as suction lines for sizing purposes. If the

recommended suction lines sizes are used,

there should be no problem with oil return.

• Vertical lines should be kept to a minimum.

Vertical liquid lines will have a vertical liquid lift

in either heating or cooling, and the weight of

the liquid head is added to the friction loss to

arrive at the total line pressure drop.

• Wherever possible, the air handler should be

installed at a higher elevation than the

condensing section to aid with oil return to the

compressor.

Linear vs Equivalent Line Length

Linear Line Length - is the actual measured length

of the line including bends. This issued to calculate

the additional refrigerant charge thatm ust be

added to the system. (See Figure #15 and

examples)

Equivalent Line Length - is the combination of the

actual length of all the straight runs and the

equivalent length of all bends valves and fittings in

a particular line.

The equivalent length of a bend,

valve or fitting is equal to the length of a straight

tube of the same diameter having the same

pressure drop as the particular valve or fitting. The

ASHRAE Fundamentals Handbook provides tables

for determining the equivalent length of various

bends, valves and fittings. Liquid and suction line

sizes as shown in Figure #14 are based on

Equivalent Line Length.

Connecting Refrigerant Lines

• Use only ACR grade copper tubing and keep

ends sealed until joints are made.

• For best performance, select routing of

refrigerant lines for minimum distance and

fewest number of bends.

• Size lines in accordance with Figure #15.

• Cut crimped ends off the air handler suction

and liquid lines. Connect and braze lines to the

air handler.

• Connect and braze lines to service valves on

the condensing section.

Figure # 14

Pressurize the refrigerant line set and air handler

to 150lbs with dry nitrogen through the Schraeder

ports provided on the self service valves. Check

line set and unit connections for leaks.

Once system integrity is verified, evacuate line set

and air handler with a good vacuum pump to 500

microns and hold for half hour.

The air handler is factory supplied with a holding

charge of dry nitrogen.

WARNING: Always wrap the body of the

service valve with a wet towel or apply some

other form of heatsink prior to brazing and

direct flame away from the valve body.

Failure to do so will result in damage to the

valve. Valve bpdy temperature must remain

below 250°F to protect the internal rubber “O”

rings and seals.

Figure 13: Valve Sizing Chart

Unit Size

Line

Type

Valve

Conn.

Size

Allen

Wrench

size

SM024/036 Suction 3/4 5/16

SM048/060/070 Suction 7/8 5/16

All Valves Liquid 3/8 3/16

Pump down must never be used with heat

pumps.

Valve

top

Schraeder

Port

1 2 ... 7 8 9 10 11 12 13 14 15 16 17 ... 31 32

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Bosch SM024 Spécifications Page 12

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