Can of Whoopa$$

[mardoman]

A Walk-in Freezer I installed back in '99 quit on me about 3 weeks ago on a Saturday nite. The remote can compressor was running, but the suction was high @ 50 psig and the head @ 150 psig and it had a whooshing noise while running.

O.K. no big deal. Order a compressor Next Day Air on Monday. Install it on Tuesday. Install went O.K. changed the contactor & LLFD, Start-up O.K. but the pumpdown seemed slow when I checked the L.P.control setting using the King valve. The compressor pumped down fine when the LLSV was de-energized. Well, O.K. I guess it will be allright.

Wrong!

Now for the past 3 days the internal thermal overload is tripping, WTF???
This Can Compressor is whooping my A$$. What did I miss ? I baby sat this thing for a couple of hours this evening trying to keep it running. Here is what I saw...... after an icebath. This is a Copeland m# CS27K3E TF5 with R-404A

WIF @ + 30 F ; Outdoor ambient 75 F ; suction @ 30 psig ; Liquid @ 195 psig
after 30 minutes of running 47 F @ suction line on compressor; 79 F liquid line @ outlet of condenser. Sight glass clear. 208-211 volts @ compressor average amps per leg 10.5-11.2 ; 266 F discharge line temp. and a crankcase temp of 311 F

A little hot huh?

Check the pumpdown @ king valve, very slow. Closed off the suction service valve and it didn't go into a vacuum promptly.

Well, I throttled the suction down to 20 psig and the liquid went to 180 psig.
suction line temp still @ 47 F amp draw now @ 8.4 - 9.0 per leg.
Discharge is now @ 216 F but now crankcase temp @ 330 F WOW ! Yea, I know mass flow rate ain't happening but when I leave the suction open it will go off again on thermal O.L. Maybe this will help??

Of course my distributor does not have one in the entire company and this is not a prime source item. Figures. So much for an easy Friday. I guess I'll be working on Saturday, St. Patrick's Day.

Now when should I celebrate? Friday or Saturday? What would a good Irish lad do?

[Special-K]

Superheat? I bet it's way high.

[mdharris68]

with the info that you provided, it appears that you are undercharged or have a faulty txv. You are only condensing 13* over ambient, about 7-15* low, and your superheat at the compressor is 50*, about 20* too high. Have you checked to see if your txv is throttling? could have a bad feeler bulb or plugged inlet screen. check out that txv before you loose another compressor. Slow pumpdown could be result of txv letting by small amount of refrigerant like its locked up. Let us know.

[razorback]

Does it have a headmaster? May be bleeding through. Has anyone else worked on the system. Mixture of refrigerants or air in the system. May have gotten a dud compressor. Just throwing out some ideas.

[markettech]

I am still digesting this - but the first thought that pops into my head is if the TXV is not throttling open properly or the screen is partially plugged, you would be hard pressed to maintain 30 psig suction on a freezer.

[hvaccop]

Pressure limiting TXV or a CPR valve

[hvaccop]

What kind of Ref?

[hvaccop]

Nevermind I see 404

[mardoman]

Superheat...Bingo! You guys are correct......... yea, way too high. This was on a warm start-up.

Consulted with Copeland.... I mean Emerson Climate Technologies. They were very helpful. They first suspected a restricted condenser. I had to install a pressure tap on discharge line to see if the highside pressure was the same as the liquid pressure at the king valve....... it was.

Next was to open the TXV all the way and see what happens. This brought the suction up to 45 psig and the suction temp down to 17 F and the discharge temp down to 205 F.
Now it's starting to make sense! I was afraid to adjust the TXV since my amp draw was already high due to the large load on a warm start-up. Another thing that had me concerned was the pressure limiting TXV. I didn't believe it would open up ( flow ) that much more. The TXV for this system is a Sporlan EFSE 1.5 ZP.

After about one hour of run time the suction was at 42 psig ; 14 F suction temp with a discharge temp of 213 F and the WIF back down to 30F.

Another thing I always believed was to set the superheat only when the appliance was in the normal operating realm. In this case + 10 F to - 10 F.
I guess I need to do some more homework. I don't think the TXV is bad but, it does make me wonder why it lost control ( starved ) after so many years. Appearance wise there is no corrosion ( rust ) on the power head nor the body. Maybe I need to just go ahead and replace it, since this is a sweat in TXV with no access to the strainer.

Thanks for your replies. Sometimes it's hard to see the forest through the trees.

Now where is me beer??

[markettech]

Superheat...Bingo! You guys are correct......... yea, way too high. This was on a warm start-up.

Consulted with Copeland.... I mean Emerson Climate Technologies. They were very helpful. They first suspected a restricted condenser. I had to install a pressure tap on discharge line to see if the highside pressure was the same as the liquid pressure at the king valve....... it was.

Next was to open the TXV all the way and see what happens. This brought the suction up to 45 psig and the suction temp down to 17 F and the discharge temp down to 205 F.
Now it's starting to make sense! I was afraid to adjust the TXV since my amp draw was already high due to the large load on a warm start-up. Another thing that had me concerned was the pressure limiting TXV. I didn't believe it would open up ( flow ) that much more. The TXV for this system is a Sporlan EFSE 1.5 ZP.

After about one hour of run time the suction was at 42 psig ; 14 F suction temp with a discharge temp of 213 F and the WIF back down to 30F.

Another thing I always believed was to set the superheat only when the appliance was in the normal operating realm. In this case + 10 F to - 10 F.
I guess I need to do some more homework. I don't think the TXV is bad but, it does make me wonder why it lost control ( starved ) after so many years. Appearance wise there is no corrosion ( rust ) on the power head nor the body. Maybe I need to just go ahead and replace it, since this is a sweat in TXV with no access to the strainer.

Thanks for your replies. Sometimes it's hard to see the forest through the trees.

Now where is me beer??

...........Hold on there for a sec before you crack that beer.

42 psig R404A after 1-hour run time? Doesn't that correspond to a roughly +8F coil?

After 1-hour, I would think your suction should be significantly lower than that, especially if the box was colder than room temp to begin with.

Superheat should be dialed in when the system is near or at design temperature.

[mardoman]

I agree with you Markettech.

Today the box was at + 40 when I did the restart.
This box has lots of bread in it and that seems to really impose a heavy load on the system. Another thing that happens at dinner time is that the customer will load up the box with the drink mugs fresh out of the dishwasher.

I did open the TXV nearly all the way. Yea it bothers me too.
I've got to go back in the A.M. to check it.

I will keep ya posted

[Special-K]

I'm agreeing with Markettech, after an hour I would expect the suction and the box temp to be lower than that. I'm concerned that you've opened that TXV too far.

You need to go back and spend some time with that sucka. Given what has happened so far, changing the valve might not be a bad idea. Give the supply house the numbers off the evap and have them size the valve by the coil capacity at the application and TD you are running.

Final SH adjustment should be done only when box is near temp. When you have one way out like you did, it's OK to adjust it to get close but you need to check again at near temp. I have a feeling you're gonna be too low now. Unless I missed something I don't see where you actually measured the Sh. You need to put thermometers on it instead of guessing.

[mdharris68]

Superheat was 6* according to the figures he gave. Way too low if he was checkign at the compressor, and a little low if checking at the evap. Prob why such a slow temp drop.

[mardoman]

K Fridge I hear ya brother, I agree. The dude at Copeland was adamant about opening the TXV all the way. I backed it off 2 turns on my final adjustment.

The dudes at Copeland had to leave early to make it to Happy Hour so I didn't get to hear their opinion on when to set the superheat. I will try to contact them on Monday.

I need to to set the S.H. but the compressor has to get the load under control and right now it's a lot. I just got to keep the suction temp low to prevent the internal O.L. form tripping, until the box is at temp. I'll find out in the A.M.

Like I said this can (compressor) is whoopin me.

[the mojo]

Suggestion time : When you replace the TXV w/ another,use a balanced port Sporland,it has a removable screen @ the inlet. Then if you hav'nt in the past, take that valve apart,examine the needle and seat,pull the rods and look for additional coking and wax built up on the rods sitting against the power head. Every picture tells a story don't it. Save your filters and cut em open to see the solids it has collected. Just think of yourself as a detective and a tech @ the same time.

[mdharris68]

how did it turn out?