walk in freezer problem

[drage93]

I been having an issue with this walk in freezer for over two weeks now. Originally went over there found evap coil frozen, heavy frost not ice. Found Peragon mechanical clock on correct time set up every 6hr for 35 min. Run manual defrost, compressor shuts off, all heaters working, coil cleared in 30 min, it ran full defrost cycle. This is 12X10 box, r-404 system. Checked pressures 30psi low 275 high, ambient at 75F. Found one of the fan motors out with cracked fan blade. Come back on Monday box seems like it at temp, everything frozen in there. Changed motor and blade, take off out there, have a feeling be back here again, didn't find anything wrong. Get a call back on Friday not working again, same thing coil iced up. Same thing ran manual defrost, thinking maybe defrost clock skiping defrost, put clock close to defrost watch it go into defrost on its own, everything check out ok. Ran manual defrost, ran out there, disconnect X on clock, thinking termination acting up. Was kind of swamp with other work this account is close to my house can show up anytime, thinking I will keep my eye on it. Get a call yesterday, cant get there till afternoon, same issue but this time I noticed the ice pattern all the way to the compressor. At this point I got have refrigeration problem here. So again run manual defrost, cleared coil come back in 3 hr. Box at 30, heavy frost build up on coil, checked pressures 25 psi low side, 250 high side, superheat at 2F, superheat at compressor 5F. txv valve flooding try to pinch down but with no result. At this point thinking bad valve. Install new Sporlan SQBE with A cartridge and SZ power head. Also found t-stat bypassed, install new t-stat. Start system up, pressures at 30 psi low side, high side at 275psi, after 1 hr run time superheat at 20F, box temp at 32F, superheat at compressor 40F. At least superheat at pump is ok now. Come back 3 hr later. Box at 25 F, superheat at 17F, again heavy frost build up on coil.

Evap Coil-Larkin LEC120BEB 12,000 bthu
Copeland C/U FJAL-B301-CFV-020
Compressor: CF09K6E-PFV-253

Checked compressor performance according to Copeland Chart
Low Side:30 psi, High side:275, ambient 90F
Compressor drawing: 11.25 amps, according Copeland right on money

I am not sure why it build heavy frost really quick, and why is not making temp. I got go back in couple of hr and see what going on with it. I have feeling it wont be working, with new valve its not flooding anymore but it still not making temp. Any inputs would be great. Thanks!! Sorry had to give a long story.

[mr_guy]

I would be suspect of the heater safety klixon at this point

EDIT:
check and make sure there are no gaps in the panels of the box, make sure the door closes properly and that the gasket is intact and sealing correctly. Are people in and out of the freezer all the time?

[2sac]

Just because you have frost or ice on the suction line back to the compressor on a low temp application, doesn't mean it is flooding. Right now, to me, it sounds like you have an air infiltration issue.

[VTP99]

What's your history with this walk-in ? Has it worked properly in the past ? Did you adjust your new valve after installing it ?

[drage93]

I had this account for 1.5 years, I am guessing who ever had it before me didn't know what they where doing because I found some other equipment all messed up as well. This walk in is been running balls out for at least the time I had account, since the t-stat was bypassed. It would run for 6 hr that it would go to 35 min defrost that it would run for another 6 hr. I don't know if the valve did some damage to compressor or it been running all this years. It's the orginal compressor from 06. As far as performed ce chart on Copeland site, compressor checks out ok. As far I know from customer they said it been working. I have not adjusted new valve yet.

[drage93]

Just because you have frost or ice on the suction line back to the compressor on a low temp application, doesn't mean it is flooding. Right now, to me, it sounds like you have an air infiltration issue.

I did check superheated on previous valve and evap superheated was 2F and at compressor 5F. That looks like flood back to me. You want minim 20F at compressor.

[drage93]

I went back over tonight, box at 32F, coil cover with heavy frost not working, check for air gaps, on one wall there was an air gap, I sealed it but I don't think that it. To build that much frost, door has to stay open for 1 hr straight, which is not the case air. We can safely eliminate air infiltration. I don't know, this one is tuff one that I have not seen before.

[fridg]

Put a door switch on to shut the solenoids & fans down on opening & leave open states.

[2sac]

What do they keep in the box? Are they using it to cool down hot products? Does the condensate drain into an unconditioned space or outside the building?

[drage93]

What do they keep in the box? Are they using it to cool down hot products? Does the condensate drain into an unconditioned space or outside the building?

Seafood and meat mostly, it drains inside building.

[drage93]

I called Heatcraft just to pick their brains. They told me txv valve is too small, they suggested I put 1 1/4 to 1 1/2 ton valve. Unit had 1 ton valve for 15 years. I don't agree with them, the condensing unit is consider 3 hp but compressor is Cf09 which is rated at 9,500 bthu at 120 condensing and -10 suction temp and evaporator is rated at 12,000 bthu. What you guys think?

[VTP99]

Open the valve up.

[fridg]

Open the valve up.

X2

Get the SH right & go from there.

[pecmsg]

I called Heatcraft just to pick their brains. They told me txv valve is too small, they suggested I put 1 1/4 to 1 1/2 ton valve. Unit had 1 ton valve for 15 years. I don't agree with them, the condensing unit is consider 3 hp but compressor is Cf09 which is rated at 9,500 bthu at 120 condensing and -10 suction temp and evaporator is rated at 12,000 bthu. What you guys think?

I wouldn't question them but look at there chart in the IOM and check it!
Change the damn valve
Adjust for 20 - 40° at the pump

then get back to us!

[icemeister]

I always question what tech support says.

From where I sit, the A cartridge in the current BQ valve should be more than adequate. Before changing to a B cartridge however, be sure to try opening up the valve to get your superheat at the evaporator down. Since you're still a ways above the design temperature for the box, I'd shoot for around 10°F superheat now and 5-6°F when it's down closer to setpoint.

Here's the Sporlan capacity charts for R404A with your BQ-A cartridge highlighted:

As mentioned, you may have an infiltration issue with this box and probably others like wet insulation and thawed /wet product, but in addition to that, you really don't have a lot of extra capacity to handle such problems. I figure the load as about 9900 Btuh for a 0°F box. It'll take time but the coil needs to be kept as clear as possible. I suggest trying 6 defrosts/day to see if helps. Once it gets down to temp you can go back to 4/day.

[drage93]

I did change the cartrige to B it seems it works slightly better. Thing is that superheat does drop around 7F after 2 he run time box drops around 10F. But after 2 he frost just becomes too much and air flow goes to crap and than box goes back to 20f. I did observe how the use this box, I think during day they just go in and out of this box constantly. I suggested installing a strip curtains and door switch and changing a door gasket. They have not approved it yet. But also they stock the the product too high around the box. And also I changed defrost during day every 4 hr.

[Idsuperheat]

Compressor is too small, 9800 Btu. 1 ton valve =12000 btu. If heatcraft recommends 1 1/4 valve then upsize and match compressor to new valve size or should I say condensing unit.

[timebuilder]

If they're in and out of that box all day, it's just like leaving the door open.... and if they won't approve plastic strip curtains, you're never going to get that box down to where you think it should be.

[drage93]

It seems like the box it’s working a lot better, I did change the door gasket and install strip curtains. But they still seem to stock the boxes around evap. I told them if they continue to do that they will have problems. In reality the way the use this box they need bigger condensing unit, compressor that can do 12,000 bthus.

[pecmsg]

Thanks for getting back with that.