Refrigerant Piping, Line Sizing, General Guidelines

035-15407-002-B-0404

)

HCE090

			*
		)			+
					+
,
				HCE120 & 150
			,
UNIT			4- POINT LOAD (LBS)
UNIT	TOTAL	A	B	C	D
	TOTAL	A	B	C	D
120	430	90	114	127	99
150	510	111	152	143	104

FIG. 6 - FOUR POINT LOADS

REFRIGERANT PIPING

GENERAL GUIDELINES

Many service problems can be avoided by taking adequate precautions to provide an internally clean and dry system and by using procedures and materials that conform with estab- lished standards.

Use hard drawn copper tubing where no appreciable amount of bending around pipes or other obstructions is necessary. Use long radius ells wherever possible with one exception—short radius ells for the traps in all suction risers. If soft copper is used, care should be taken to avoid sharp bends which may cause a restriction.

Pack fiber glass insulation and a sealing material such as per- magum around refrigerant lines where they penetrate a wall to reduce vibrations and to retain some flexibility.

Support all refrigerant lines at minimum intervals with suitable hangers, brackets or clamps.

Braze all copper to copper joints with Silfos-5 or equivalent brazing material. Do not use soft solder.

Insulate all suction lines with a minimum of 1/2" ARMAFLEX or equal. Liquid lines exposed to direct sunlight and/or high tem- peratures must also be insulated.

Never solder suction and liquid lines together. They can be taped together for convenience and support purposes, but they must be completely insulated from each other.

A filter-drier MUST be installed in the liquid line of every system to prevent dirt and moisture from damaging the system. A properly-sized filter-drier is shipped with each condensing unit for field installation near the evaporator coil. The filter-drier and is taped to the top of the compressor.

NOTE: Installing a filter-drier does not eliminate the need for the proper evacuation of a system before it is charged.

A moisture indicating sight-glass may be field installed in the liquid line(s) between the filter-drier and the evaporator coil. The moisture indicating sight-glass can be used to check for excess moisture in the system or used as a visual means to verify refrigerant charge.

LINE SIZING

When sizing refrigerant lines for a split-system air conditioner, check the following:

1.Suction line pressure drop due to friction

2.Liquid line pressure drop due to friction

3.Suction line velocity for oil return, and

4.Liquid line pressure drop due to static head.

NOTE: Never base refrigerant line sizes on the O.D. of the suction and liquid connections on the unit.

Tables 4 and 5 list friction losses for both the suction and liquid lines on the system. Table 6 shows the amount of refrigerant charge required per foot of refrigerant line.

When the evaporator coil is below the condensing unit, the suc- tion line must be sized for both pressure drop and for oil return. For certain piping arrangements, different suction line sizes may have to be used. The velocity of the suction gas must al- ways be great enough to carry oil back to the compressor.

When the condensing unit is below the evaporator coil, the liq- uid line must be designed for the pressure drop due to both fric- tion loss and vertical rise. If the total pressure drop exceeds 40 psi, some refrigerant may flash before it reaches the thermal expansion valve. This flashing will not only cause erratic valve operation and poor system performance, but could also dam- age the expansion valve.

SERVICE VALVES

These condensing units have service valves on both the com- pressor suction connection and the liquid line leaving the con- denser coil.

The liquid and suction line service valves are shipped from the factory front-seated and closed with the valve stem in the maxi- mum clockwise position.

Both of the service valves have a 1/4" male flare access port for evacuating, charging and pressure checking the system.

NOTE: Never remove a cap from an access port unless the valve is fully back-seated with its valve stem in the maximum counter-clockwise position because the re- frigerant charge will be lost. ALWAYS USE A RE-

FRIGERATION VALVE WRENCH TO OPEN AND CLOSE THESE SERVICE VALVES.

Unitary Products Group