R409a problems

[Toddbrewster]

I am still missing something, I have a customer with a walk in cooler in a bar its a 409a system, complaint was the evap. ices up intermittently at first now it ices up and wont get down to temp. The customer has done a lot of work on the cooler, the panel seals were all not sealed, the ceiling was falling in and the unit could not keep up. Now they have sealed the cooler, added insulation and covered that with steel siding, along with replacing and reinsulating the floor, all thats left is to align the door so it seals better. At first they had the unit running and it would pull down to 40-42 degrees. Now it runs 48-50. I stopped and checked the charge and operation out, liq press 160#=106f, suction 32#=36f, box 48-50, ambient for the condenser 80-85. Liquid temp was 99f, suction at the evap outlet/txv bulb 47f, air outlet from the evap about 50-52. The sight glass is clear, this system has a reciever, my subcooling was about 6, and super heat 10-11 at the evap outlet/txv bulb. I added some 409a to increase my subcooling to see if that would help, but not much difference, I have tried lowering and increasing the superheat to try and get my air outlet temp down, when I left I had about 6 superheat at the evap outlet, 12-15 at the compressor, 8 subcooling, 165 liq press=108f 99f liq line, 30# suction=36f, 40f evap outlet, 48-51f at the compressor, my evap outlet was about 46-48f. I checked with the customer this am and the box got down to about 42-43 but the coil again is starting to ice up. The thermostat does shut the unit off and the system pumps down and stays. I am missing something I dont understant why I cant adjust this system to maintain 38-42 for this walk in cooler. As is they are happy it is keeping the keg beer and can beer cold so when they move it to the bar it is almost at the temp they want but the health department is on them about the walk in temp as they serve food and want to store the food in the walk in but cant get the temp down low enough. Is there something I am missing?? My next step is going to be to pull the charge out, and add it back in till the sight glass clears and see if that makes a difference. I dont see where this system is over or under charged, the txv is brand new. This is the 3d walk in with 409a and I have struggled with all 3. I work on quite a few walk in coolers and freezers but cant seem to get the readings I want with 409a. My other thought is as far as I know when this cooler was set up it was for a beer cooler only in the last year has the customer started serving food, maybe this set up is not designed to go lower than 45??

[2sac]

Warm beer takes awhile to get to temp. That being said, if I'm reading this correctly you have a 36 degree coil and a 48-50 degree box. 40-42 is still too warm for beer, especially kegs. Does it get down to temp when it's not icing up? It seems to me the ice up may be because the stat is not being satisfied and pump is running continuously. Are all the humidity/air infiltration issues addressed besides the door? How close is your amp draw to rla? Does the compressor pump into a vacuum? Have you watched the compressor long enough to see if it may be cycling on overload? Outdoor ambient?

[hvac wiz 79]

Yea id prefer 35-38 range for my beer coolers.

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[refertecbd]

What is the size of the box and the Condensing unit and Evap. Model number? Maybe the system is undersized for the size of the box. Just a thought.

[smilies]

I am still missing something, I have a customer with a walk in cooler in a bar its a 409a system, complaint was the evap. ices up intermittently at first now it ices up and wont get down to temp. The customer has done a lot of work on the cooler, the panel seals were all not sealed, the ceiling was falling in and the unit could not keep up. Now they have sealed the cooler, added insulation and covered that with steel siding, along with replacing and reinsulating the floor, all thats left is to align the door so it seals better. At first they had the unit running and it would pull down to 40-42 degrees. Now it runs 48-50. I stopped and checked the charge and operation out, liq press 160#=106f, suction 32#=36f, box 48-50, ambient for the condenser 80-85. Liquid temp was 99f, suction at the evap outlet/txv bulb 47f, air outlet from the evap about 50-52. The sight glass is clear, this system has a reciever, my subcooling was about 6, and super heat 10-11 at the evap outlet/txv bulb. I added some 409a to increase my subcooling to see if that would help, but not much difference, I have tried lowering and increasing the superheat to try and get my air outlet temp down, when I left I had about 6 superheat at the evap outlet, 12-15 at the compressor, 8 subcooling, 165 liq press=108f 99f liq line, 30# suction=36f, 40f evap outlet, 48-51f at the compressor, my evap outlet was about 46-48f. I checked with the customer this am and the box got down to about 42-43 but the coil again is starting to ice up. The thermostat does shut the unit off and the system pumps down and stays. I am missing something I dont understant why I cant adjust this system to maintain 38-42 for this walk in cooler. As is they are happy it is keeping the keg beer and can beer cold so when they move it to the bar it is almost at the temp they want but the health department is on them about the walk in temp as they serve food and want to store the food in the walk in but cant get the temp down low enough. Is there something I am missing?? My next step is going to be to pull the charge out, and add it back in till the sight glass clears and see if that makes a difference. I dont see where this system is over or under charged, the txv is brand new. This is the 3d walk in with 409a and I have struggled with all 3. I work on quite a few walk in coolers and freezers but cant seem to get the readings I want with 409a. My other thought is as far as I know when this cooler was set up it was for a beer cooler only in the last year has the customer started serving food, maybe this set up is not designed to go lower than 45??

If the thermostat is satisfying and shutting down, why not turn down the thermostat?? Also, you may have overcharged the unit, torch the receiver to find the level.

[Toddbrewster]

The cooler has been running for a few days now with keg beer and case beer in it. The box isn' t really getting to temp, the lowest it has been lately is 40-42 which is over night and the coil ices up when they come into the bar in the am. The unit seems to run continuous to maintain this temp. Maybe the kegs are not completely cooled off as the cooler was off for 3 weeks while they resealed and reinsulated it, the temps here have been really hot lately mid 90's and very litttle to no a/c in the bar, none what so ever by the walk in. I got this cooler up and going a couple of years ago, and they have been very happy with it, once in a while it would ice up they said, but I am not sure what temp they were maintaining as they just keep beer in there, they have other coolers at the bar they keep the beer in before selling it. I am thinking maybe the unit is not sized to maintain below 45. They have had no complaints until recently when they opened the kitchen and wanted to store food in the walk in. The infiltration is almost all sealed, the only gap is the bottom corner of the door, the hinges are wore out and the door does not line up quite perfect, you can see light coming in around the bottom corner of the door, but the cooler is 10x more sealed than it was 3 weeks ago. I do not remember how the amp draw was in relation to the fla on the name plate, and I have not seen the unit tip on internal ol. The compressor seems to run a lot to maintain cooler than 45. if set 48-50 it will maintain that box temp, and will cycle on and off from the stat. The compressor will pull into a vacuum i dont remember how much of a vacuum, but it will pull into a vacuum, as I changed out the txv earlier this summer it would not adjust what so ever, so I pumped the system down and switched it out, now I can control the superheat, just cant seem to get cold enough which is why I thought I would remove the charge and re charge it and see how it does, would like to get the suction down some to lower the coil temp, thought maybe I am slightly over charged which the pressures and temps I have it does not appear to be over charged. As for the size of the box and evap I will have to check tomarrow night, as I am going back to try and get this thing down, I was going to measure the box and get the info from the evap. I agree I like 35-38 for a beer cooler, and I am sure the health inspector would love it if the box was in that range for the food they want to keep in there. Thanks for the good ideas, I will keep ya posted and see what I learn tomarrow, will be glad to get this going as for some reason I seem to be getting my tail kicked by 409a.

[VTP99]

Maybe the system is undersized for the size of the box. Just a thought.

[jim147]

They have had no complaints until recently when they opened the kitchen and wanted to store food in the walk in.

How many door openings did this add and what kind of heat load did the kitchen add to the unit?

jim

[Toddbrewster]

No doors were added, they had a small kitchen already in place, not sure how much heat load the kitchen added, the walk in is a room or two behind the kitchen.

[duguay320]

No doors were added, they had a small kitchen already in place, not sure how much heat load the kitchen added, the walk in is a room or two behind the kitchen.

I think he meant that they are now in and out of the cooler all day long. With it being 90ish as ou said in your area lately it doesn't take to much to get a kitchen easily over 115. With that kind of ambient being introduced into the box frequently it will have a hard time hitting proper temps away from t-stat. Also how much food is in the box now could have overloaded an already struggling system especially if putting in hot foods frequintly. Also did they add any rack to unit? potential airflow issues. again hitting temps at t-stat but not far side of box.

[jim147]

Yes, I was wondering how many times they are opening the door now.

duguay320 seems to have seen this a time or two.

jim

[Capz]

Hey, what would happened if someone came along and added let's say R414B? Or what about R22? What this tamper with readings?

Another thought, did you visually inspect the back side of the evaporator? Is it clean?

[K_Neil]

Why not reclaim the 409a and switch to 414b?