Refrigerant Line Insulation

[Rich Wallace]

Last weekend I was looking over the engine room on my new to me P42 and noticed the refrigerant lines running through the engine compartment from the compressors to the refrigerator and freezer. (It has a separate compressor for each box.) Anyway, they were bare copper with no insulation of any kind. This is my first boat with refrigeration and I have no experience with what could or should be done with those lines. It just seemed to me that that they would be picking up engine heat. Should they be insulated? Should the lines be separated so the hot and cold ones are not touching? What kind of insulation can be used in the engine compartment?

 

[Victor Robert]

Not a problem

Unless you are running your engine a long time every day - in which case you should have bought a trawler - the lack of insulation is not a problem. Remember that the lines are not carrying heat and cold, but liquid and gas. The compressor compresses the refrigerant gas to its liquid state and pushes it up the tube to the evaporator. The evaporator allows the liquid to evaporate to its gas state - an endothermic process (consuming heat) - which is what produces the cooling. You want to ensure that there is adequate insulation in the hole where the tubes exit the refrigerator box to the engine compartment. Also try to isolate the engine compartment air from the airspace around the refrigerator and freezer box.

 

[Alan]

Insulation corrected a sweating problem

The insulation on the cold line from the compressor to the cold box was badly deteriorated on our H340. There was always a fair amount of water in the compartment where the compressor is located and the line had frost in several locations. I re-insulated with regular pipe insulation and vinyl tape from Home Depot. It cured the frost/sweating problem and the compressor doesn't come on quite as often now. Everything is much better after the reinsulaton and the cost/time to do it was minimal.

 

[Victor Robert]

Frost on refrigerant return line

If the copper line from the evaporator back to the compressor is frosted all the way back to the compressor coupling, the system is overcharged. More is not better when charging with coolant. The system must be charged to a level that allows a balance between the liquid side and the gas side. Too much coolant impedes the evaporation process.