ReplySo whats the SH??? And SC???
Professional Member*
I had a call for a reach in freezer that was not working. After thawing out the evap coil. I noticed the txv had been messed with(Cap was off and on skid). I recoverd the "juice" checked to see where the txv was adjusted to. It was opened up all the way. I then counted the revolutions open to closed. It was 8. So mid seated the adjustment to around 4. Pulled a good vacume and weighed in 20 oz. I am now checking superheat. What do you think?
Professional Member
So whats the SH??? And SC???
Professional Member*
SH is down to 20 last checked this morning. Didn't get a chance to get back to it this afternoon. Freezer temp -10 f.
Low side:-20 saturation. PSIG?
I'm trying to go off of memory (not working)
All the parameters for the intellitrol were great.
Defrost cut in/out -10 to 9 F
Termination temp. 45 F
Global Moderator
20* SH sounds pretty high for a freezer. Where are you checking your SH ?
Professional Member*
Yes sir that's high. I'm checking right out of the evaporator cabinet.
Professional Member*
I'm looking for 7 to 9 SH. I'll check it all out tomorrow and post the prudent info. needed. It's been busy.
Global Moderator
You could go as low as 4 and be safe from flood back.Originally Posted by blazey10
Professional Member*
Ya know, we may have gotten off on the wrong foot......you don't seem to be half bad after all.
"The problem is the average person isn’t tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and it’s not in the movies they watch, and it’s not in the few books that they buy, they don’t get it" - Jack Canfield
Professional Member
Since this is a self contained unit with probaly a very short suction run to the compressor. It will also be a good idea to check compressor superheat. Most manufactures are going to recommend not too much lower than 20* superheat at the compressor.
On these small systems compressor superheat will trump evap coil superheat.
A nice efficient evap coil doesn't mean much when a compressors drinking liquid.
Professional Member
Seeing as how the evaporator cabinet is about 12 inches away from the compressor, I don't think 20 degrees of superheat is high. I think its perfect.
Professional Member*
intel-a-traul temp. is -14F
Liquid line temp. 92
Liquid Sat. 94
High side 220 PSIG
Low Side 10 PSIG
Low side line temp. 21
Recap: TXV was wide open. I mid stroked the adjustment(halfway between open and closed) Weighed in new charge. This is where I am at now. I suppose TXV was opened up all the way by another tech to lower superheat, or is thought wrong? Now I'm confused.
Professional Member
how much refrigerant was recovered? was it under or over your 20 oz ?
Professional Member*
So am I.
When you said the reach in freezer was not working, what did you mean, precisely?
Was the compressor not running?
Was the compressor running, but kicking out intermittently?
Was the compressor running continuously but not maintaining case temp?
Was the evap coil iced up?
Were the evap fans running?
Was the system stuck in defrost?
"Not Working" is such a vague term. It's hard to offer advice when the only thing we know is the freezer was not working - you pulled the gas - tweaked the valve - and added gas.
Why did you feel it was necessary to pull the gas? What was the unit doing (or not doing) that made you feel it was necessary to throttle the TXV closed so far?
Based on your latest post (and I'm making an assumption on R404A being used), your low side pressure was 10 psig and your suction temp (again, I'm making an assumption it was at the outlet of the coil) was +21F.
By my calculations, the unit is running at about +51F superheat. This is a helluva lot higher superheat than you had indicated yesterday.
You may have a TXV not functioning properly - but it's hard to tell with the information given.
"The problem is the average person isn’t tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and it’s not in the movies they watch, and it’s not in the few books that they buy, they don’t get it" - Jack Canfield
Professional Member*
20 oz.
Global Moderator
You had me at hello
Ya know, we may have gotten off on the wrong foot......you don't seem to be half bad after all.
Professional Member*
I just threw up in my mouth a little bit.......I'm ok now tho.You had me at hello
"The problem is the average person isn’t tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and it’s not in the movies they watch, and it’s not in the few books that they buy, they don’t get it" - Jack Canfield
Global Moderator
Glad to hear your O.K.I just threw up in my mouth a little bit.......I'm ok now tho.
Now back to the thread. What is his refrigerant ? Kind of hard to get SH when you don't know which chart to use. Going off your guestament of 50+* how does one get a -10* box temp ?
Professional Member*
I'm a little hesitant to correct you since were getting along so well and everything.......but I think at last report the temp was actually -14F.Glad to hear your O.K.
Now back to the thread. What is his refrigerant ? Kind of hard to get SH when you don't know which chart to use. Going off your guestament of 50+* how does one get a -10* box temp ?
10 psig fits ok in my mind with a -14F box temp (making an R404A assumption of course).
That said, if the +21F was measured near the compressor - I would simply think it's a matter of dialing in the SH a touch. But, we just don't know.....
"The problem is the average person isn’t tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and it’s not in the movies they watch, and it’s not in the few books that they buy, they don’t get it" - Jack Canfield
Professional Member*
Well that's the problem! Was handed the job by another tech in the middle of his diagnoses of the freezer.
Initially the evapoorator was iced up. Leaked searched( didn't find leaks) Noticed txv had been adjusted. I wanted to start fresh and go from there. I have orderd new TXV and Drier. Superheat has gotten out of control obviously. I got my self confused though. To increase superheat you open TXV(allowing more refridgerent in?) If your ambient temp. or enviorment was out of the norm.
Professional Member*
Oh dang. sorry 404 is the refridgerent. Thought everyone knew! Just kidding. I'm not use to typing my thoughts yet.
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