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What is the purpose of Refrigerant Piping Insulation?

This document describes what is the purpose of Refrigerant Piping Insulation?

Product line:
All Cooling Products.

All Product models, All serial numbers.

The purpose of this document is to provide a clear communication regarding insulating the external copper refrigerant lines.


Internal to an air conditioner suction lines temps are about  (40°F (4.4°C)  and cause condensation when ambient air is introduced that is below the dewpoint of the coil/suction lines.  In addition, any heat that enters the refrigerant adds to the superheat and reduces system efficiency. For these reasons, suction lines should be insulated with a vapor proof insulation. This is a requirement of many building codes. Insulated suction lines are completed by Schneider Electric’s.  If for some reason the suction line piping is not insulated please advised your Sr. TSE and, or TTL.

Liquid lines generally are insulated. They are warm to hot (110°F (43.3°C) for air-cooled). If liquid lines pass through a space that is warmer than the refrigerant (i.e. the roof of a building at roof level), or if they could be considered hot enough to pose a safety risk, then insulation should be added. Long runs of liquid line that are exposed to high ambient temperatures should be insulated to maintain proper sub-cooling values on the system.  Discharge lines are generally un-insulated. They may be also very hot, in excess of 150°F (66°C), so insulation may be warranted as a safety consideration, or if the heat loss from the discharge gas line would be considered objectionable to the space.

After the pressure test and evacuation have been confirmed charging can commence.  Due to most refrigerants being a blend these need to be charged as a liquid.  However charging liquid to the compressor is not advised to avoid oil wash out.  The best location to charge is at the outlet of the flooded receiver or liquid line.  This simply requires a shut off valve and an access port downstream of the valve.  When charging the valve will be closed creating a vacuum downstream allowing liquid refrigerant to be drawn into the system.

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