Split ductless heat pump conversion
- Thread starter mbrummal
- Start date
Just throwing it out there and not trying to start an argument but... If you can't hook gauges up before the metering device (capillary tube in this case) that chart doesn't do you a bit of good.. Just sayin.
I thought you used suction pressure (after evaporator, waaaay after capillary tube), suction line temp and the indoor and outdoor ambient temps to determine superheat. And you use the liquid pressure (before the capillary tube) and liquid line temperature for subcooling. Is that wrong?
I have access to the suction pressure on that unit but not liquid presssure so I should still be able to determine the superheat.
I have access to the suction pressure on that unit but not liquid presssure so I should still be able to determine the superheat.
The system uses the thermistors to sense refrigerant temps, air temps etc and modulates the flow of refrigerant via the compressor based on a set of proprietary numbers that each manufacturer has come up with. The only system I know of (I only work with Daikin & Midea) that actually has a published number that I could find is the Daikin RMXS48, it's superheat is 37.5F, caveat being that it's only in a lab situation under controlled conditions and completely variable in the real world. So yes there is superheat but it does absolutely no good to know the number when it will always vary and from a troubleshooting perspective you just test thermistors, airflow, reverse the cycle to get high and low pressures (to see if their in range) and output air temps. All that and the error codes will diagnose the equipment. If a tech tells you it will get you "close" then find a new tech because "close" has been the F-up the HVAC industry has been making for years.
I know they don't have a published spec for this unit. Technically, the correct way to check the charge is to weight in the refrigerant, just like in cars. But that isn't always practical.
On other (newer) split systems with variable speed compressors and condenser fans, I agree, checking the superheat won't do you much good at all. This one, on the other hand, has a fixed speed compressor and condenser fan and was tested with the evaporator fan on its highest speed.
On other (newer) split systems with variable speed compressors and condenser fans, I agree, checking the superheat won't do you much good at all. This one, on the other hand, has a fixed speed compressor and condenser fan and was tested with the evaporator fan on its highest speed.