Hot Gas Bypass for DX systems
Hot Gas Bypass for DX systems
(OP)
I recently read an article going on and on about the evils of hot gas bypass for capacity control. We have specified hot gas bypass on numerous systems for increased capacity control several times. Does anyone have any comments about hot gas bypass?





RE: Hot Gas Bypass for DX systems
Though I don't have experience with large systems, I heard the life of compressor gets reduced with hot gas bypass.
Regards,
RE: Hot Gas Bypass for DX systems
pennpoint
RE: Hot Gas Bypass for DX systems
Its very easy to do both poorly however.
RE: Hot Gas Bypass for DX systems
RE: Hot Gas Bypass for DX systems
I had HGBP designed on a 30 ton split system for a library. The contractor provided an APR valve for low capacity control. Anybody have experience with these?
RE: Hot Gas Bypass for DX systems
With this system the hot gas is mixed in evaporator and, therefore, not only raises the low side pressure, but also provides a false load, defrosts the coil, increases refrigerant velocity within the evaporator, and generally eliminates the need for de-superheating with a liquid injection valve.
The expansion valve feeding the evaporator has its remote bulb and equalizer connected to the suction line leaving the evaporator. Thus, when superheat increases, it will open and feed liquid refrigerant into the evaporator along with hot gas until such time as the load increases to permit bypass valve to close. Hope this can help you.
RE: Hot Gas Bypass for DX systems
For medical cooling applications (chiller cooling and MRI) we do not use HGBP because the chiller is at 10-20% load MOST of the time, so HGBP is very inefficient. It is easier to just use two compressors. They also do not have tight temperature control requirements.
Look up the Copeland Digital Scroll. It is an interesting answer to HGBP. It has been used mostly for air dryers and from what I have heard has been successful.
Good Luck,
Clyde