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Suction solenoid
Open Display case , condenser outside , Russell, R22
Why would they have a suction solenoid instead of liquid line solenoid ?
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I've honestly never seen that. It could be because they like slugging the compressor with liquid lol.
Are you sure it's not a pressure regulator? I've seen those on old reach in hussman units
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Suction stop solenoids are used on RAC systems. Not on single condensing units!
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My buddy installed it few years ago and he called the manufacturer at the time questioning where the liq line sol was , and they said just install the 7/8 suction that comes with it
I was dropping off some freon for him today and heard it shut off weird .. and i was like WTH was That ?
Which brings me here
Let me ask what brand it was .... brb
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Originally Posted by
pecmsg
Suction stop solenoids are used on RAC systems. Not on single condensing units!
do they have liq line as well ?
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Originally Posted by
Snapperhead
do they have liq line as well ?
NO!
On a rack system they open slowly. Allowing small amounts of liquid into the suction line. They dont work on single compressor units.
Have him install a liquid line solenoid on that unit.
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Honestly suction stops are more common on parallel rack systems.
Benefit to using a suction stop is the case will immediately stop cooling when it closes where as using a liquid line solenoid it has to pump out and pump down which could cause it to breifly get too cold.
Wont likely see that on a single short coupled condensing unit, but on a rack system thats not an ideal setup.
Open air cases work great with EPRs being used for temperature control
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The evaporator filling with refrigerant during off cycle seems to greatly help with defrost in my experience. That being said, it is hard on individual compressors and better suited to rack systems as mentioned by others.
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Tyler Refrigeration specified suction stop solenoids for some of their cases with conventional or single compressors. They didn't result in floodback or slugging.
If you think about it, during the off-cycle the TXV in the case sees no difference between the suction stop and the compressor shutting off.
How can the evaporator flood with liquid in the off cycle or during defrost? Just because you don't have a liquid line solenoid valve doesn't mean the expansion valve is going to continue to feed during the off-cycle. It's a hard shutoff, so when the suction stop solenoid closes the evaporator pressure rises, fully closing the TXV. When the suction stop opens the evaporator pressure drops and the TXV starts to feed once again.
The suction stop method also can be helpful for pumpdown control on systems with large evaporator operating charges and small receivers.
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Ive found on a couple jobs that have a very long linset runs changing to suction stop solenoids or moving the liquid solenoid as close to the txv as possible can alleviate crankcase oil foaming problems during long pumpdowns. I had a meat processing walkin once that tripped on oil once in a while while pumping down. Installing a suction stop valve shortened pump down time by more than 50% - no more oil safety trips!
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