what are symptoms of upside down LLSV?

[The Doctor]

Is bypassing refrigerant in off cycle, and

floodback ---are these symptoms?

I'm curious about a job that I'm looking at tomorrow. The LLSVs were recently rebuilt, Alco240ra 8, with plug(no bypass stem). The report is that the liquid lines sweat in off cycle and/ or freeze up,

that there is flood back and low suction with one of two parallel 14ton scrolls running, and that with both compressors running that it runs "okay", but has "never run quite right".

This is a MCC airhandler (017) with a 30ton condenser. One compressor was taking out the CB, and I'm going to startup the new comp. and evaluate why first compressor could have failed.

Back to the original question, about upside down LLSVs. (two LLSVs, both of which feed two txvs). Main fan VFD is running at 60Hz.

[markettech]

If you are asking what I think you are asking........liquid line solenoid valves can be mounted horizontally or vertically.

They can NOT be mounted upside down.

(There's this little thing call gravity that tends to affect them negatively if they are upside down.......)

[powell]

Doctor,

Dirt and debris could be your problem with an upside down LLSV. Check out this link, page 21.

http://www.emersonclimate.com/flowco.../TechGuide.pdf

[frigeguy]

I'm curious about a job that I'm looking at tomorrow. The LLSVs were recently rebuilt, Alco240ra 8, with plug(no bypass stem). The report is that the liquid lines sweat in off cycle and/ or freeze up,

This is common on old solenoids, it also says recently rebuilt, why were they rebuilt? I see this all the time. Ok so the solenoid is worn out? It started to jam open or not close completely on the off cycle, which will cause frosting on the liquid line, or sweat ...depends on how much its leaking by. Rebuilding the liquid line solenoid (replaceing the disc etc.) does not always solve that problem. If its older and what I call worn in then there could be wear on the brass itself. The rebuild kit may work or appear to work, but gets hung up now and then causing frosting or sweating of the liquid line in the off cycle. This could lead to more serious problems eg. flooded starts on compressors.
Perhaps thats why I only carry complete sporlon solenoids, not the kits. I tend to charge more hours and parts making the company money, but it seems new solenoids tend to work every time. The company looks good, no call backs, and $$ in their pocket and mine

I have also replaced new LLSV valves at start up on new racks ...either defective (machineing tolerences) or warped from poor install practices. Same symptoms, sweat or frosting of the liquid line after the LLSV.

[markettech]

From Alco:

Note: Mounting enclosed tube more than 90D off vertical up position is not recommended.



...........this topic can (and most likely will) get beaten to death. Bottom line, the solenoid valve is going to give you grief if it is mounted upside down.

Yes, wear may exacerbate the problem, but mounting the valve upside down is not recommended.

[The Doctor]

thanks for the pdf, and for the replies.

Now then I will say what I'm thinking, instead of beating around the bush.

I think the valves are backwards. Why I typed Upside down??? (shrug shoulders)--thinking, "nah, can't be...can it?

I hope I'm wrong, but we didn't install it. Im just called the milkman until the problem is solved.
Then silence is golden.

[markettech]

thanks for the pdf, and for the replies.

Now then I will say what I'm thinking, instead of beating around the bush.

I think the valves are backwards.

There should be an arrow on the valve somewhere or it may even be stamped "IN" on the inlet side of the valve.

[The Doctor]

I'm chomping at the bit to have a look at this thing, before I would do a startup.

[markettech]

Good luck, let us know how it turns out for ya

[JD Perkins]

A valve in backwards will let gas through during the off cycle. I saw this once with a rookie. He had replaced the valve and the customer called back later saying the case was too cold. I sent the tech back and he was having problems finding the solution. I went up and took a look and the first thing I saw was the arrow pointing in the wrong direction. It was allowing refrigerant to feed through the valve. Needless to say it was a lesson learned.