I have a bit more complex system than I wanted to have.
Two boxes with their thermostats. Freezer
set at 24F with 3F differential
Fridge set at 45F with 3F differential. Refrigerant is R134A
1/2HP 110V compressor
is mounted on condenser tray to which i added 1/2 ton water
coil. Leaving compressor
, refrigerant goes into water cooling heat exchanger
, then into original tray foils with fan blowing over them. After that I have a receiver with king valve, then two packless valves with dryer and then a sight glass.
1/4" liquid line has a tee, and right after the tee, solenoid valve is controlled by a fridge thermostat. This valve controlls fridge evaporator plate with sporlan FJ 1/4C TXV
thermostat controls the compressor, fan and water pump
So I could have fridge solenoid ON and open with system not running. But when freezer thermostat is off, the system is off.
Two times in the last week i had liquid flood back to compressor at the time fridge set point was reached and freezer was still running. I did not add a suction accumulator but I did order it and I plan to install it.
Since I still had gauges connected I noticed that at the time of floodback, with fridge loop off, my suction pressure was 10PSI. Typically with freezer working from 24F to 27F, and fridge off, my suction pressure is at 0PSI. When fridge line opens, that pressure is around 5-10PSI.
Thermostat sensors are NOT mounted on evaporator plate. instead they are about mid way up the very deep boxes and on opposite side from evap plate. Not sure if this is correct or not?
Fridge TXV is new but I did not replace the freezer TXV so that is original from an unknown origin. I could not make the markings on it, but it has 3/8" inlet and 1/2" outlet. even though line going to it is 1/4". it just has a bigger flare nut.
R134A was used before so i imagine that TXV is appropriate. I did look at the inlet screen
and it was free of debris.
before I replace a freezer TXV and add suction line accumulator, are there any suggestions on my hypothesis that as fridge shuts off, liquid refrigerant floods the compressor via freezer TXV. Both TXV bulbs at 1 o'clock position with copper line about horizontal. They are wrapped in pipe foam insulation
with zip ties.
Is there something else I should be checking?
I thought maybe raw water
strainer was clogged but I am not so sure anymore. That would cause higher high pressure line. That pressure typically remains around 85-100PSI. Its measuring already cooled refrigerant.
Compressor discharge line is hot, cannot touch it, but after water loop and fan, at the receiver it is already very cool. 1/2ton was smallest water loop i could find.