Two stage DX cooling coil
Two stage DX cooling coil
(OP)
Dear fellows:
Some field inspectors like to instructs us on installing solenoid valves at the liquid inlets of two-stage DX cooling coils. Could anyone tell me the reason for this? Are they really required or just optional?
Thank you!!!
Some field inspectors like to instructs us on installing solenoid valves at the liquid inlets of two-stage DX cooling coils. Could anyone tell me the reason for this? Are they really required or just optional?
Thank you!!!





RE: Two stage DX cooling coil
Solenoids are definately not an option, but can be the difference between compressor(s) lasting 2 years or 20 years.
Thus, the controller energizes a solenoid and the compressor is controlled by the low pressure control. (Plus the additional safeties)
RE: Two stage DX cooling coil
Ken
Ken
KE5DFR
RE: Two stage DX cooling coil
Compressor short-cycling can be devastating to motor windings and starting controls because of overheating. However, the cut-in pressure has to be low enough to ensure that the system will cut in once the liquid-line solenoid is energized by the thermostat to start the next on cycle. These pressures are dependent on refrigerant type and the box temperature desired.
RE: Two stage DX cooling coil
3. Evaporator capacity control β you can decrease the evaporator surface area by isolating a coil / TXV. When a compressor is unloaded or common compressor(s) is turned off, you need to match the evaporator area to the compressor capacity. The LLSV will remove a section of an active coil / TXV. Most TXV are only good to 50% of the nominal tonnage.
You should review the manufactures installation instructions details on the application of when a LLSV is required. I would not want a local inspector telling me he wants a pump down on systems that does not require one. Most codes require the system to be installed as per the manufactures instructions.