When multiple compressors are piped together with a common
suction and discharge header - such as with the arrangement of a parallel rack
configuration - oil return to each compressor is a major concern. Typical oil
recirculation rates are dependent on three factors.
Bob has gone on a service call where the customer is complaining that her house is not getting up to temperature. The house was heated with a heat pump with three stages of auxiliary strip heat. Bob removed the panel to the strip heat and found one of the units was not pulling current.
This troubleshooting situation is a look ahead to the upcoming cooling season. Our customer has called to say that their heat pump “isn’t cooling at all,” and while the outdoor temperature is only in the mid 80’s, it’s quite uncomfortable in the house. You find that the underlying reason is that the compressor and outdoor fan motor aren’t operating.