HVAC/R Tip: No Oil Return, It Might Be Your Suction Line Accumulator
Tip: No Oil Return, It Maybe Your Accumulator...
By Gary McCreadie
Having oil return problems? It might be an issue with a plugged screen on your suction line accumulator. If you are not aware, suction line accumulators are installed in series with the suction line to protect the compressor from liquid returning and causing a flood back situation. It does this by allowing liquid to settle in the base of the cylinder while vapour at the top of the vessel will continue to flow back to the compressor. In the image below, you notice there is a small opening at the bottom of the U-shaped pipe. That opening allows for oil return back to the compressor. If for any reason that screen becomes obstructed, you will have oil return issues. If you are experiencing oil return issues or receiving nuisance oil failure calls, it would be recommended to replace the suction line accumulator if everything else checks out okay.
Check out this video, a suction line accumulator was cut open after an oil return issue.
The image below is a fantastic cut out example of a suction line accumulator. I took this shot at the Emerson Climate Technologies office in Brantford, Ontario. Refrigerant enters the cylinder on the right hand side. If any liquid is present, it will settle at the bottom of the cylinder, vapour will travel back to the compressor from the top right opening of the U-shaped pipe, exiting out the accumulator on the left hand side.