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.

Sent from my HTC Sensation 4G using Tapatalk 2

[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.

:ditto: :yes:

[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. :cheers:

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?

[icemeister]

Unless the existing refrigerant is compromised by the mixing other refrigerants as Capz suggests, the system performance won't be significantly improved by switching to another R12 interim replacement refrigerant like R414B or R401A. There's nothing inherently bad about R409A.

I think we need to get back to some basics first...like doing a quick load calc for the box and comparing that to the expected capacity of the existing system.

What is the size of the box?

What is are the model numbers of the condensing unit and evaporator?

If the load and capacity appears to be in line, then perhaps checking the compressor performance would tell a tale. Get the suction and discharge pressures along with the amp draw and input voltage at that condition. With that info, we can go to the compressor manufacturer's performance data and determine what the amperage should be.

[Russ57]

I may be reading the info all wrong....but it seems like you are saying the discharge air temp off the evaporator is the same, or warmer, than the box temp.

I'd also like to know what your compressor amps are compared to its rating.

We have to know if you have the right airflow and TD across the evap. Maybe they sealed and insulated that evap when they did the work on the box???

[Dchappa21]

I may be reading the info all wrong....but it seems like you are saying the discharge air temp off the evaporator is the same, or warmer, than the box temp.

I'd also like to know what your compressor amps are compared to its rating.

We have to know if you have the right airflow and TD across the evap. Maybe they sealed and insulated that evap when they did the work on the box???

That's what I read too... Mixed gas or oil logged evap would be my vote. :.02:

[Tommy knocker]

Were there any other changes made during the resealing of the box? Where is the cond unit in reference to the evap? Is the TXV hunting or steady? Is there a full colum of liquid feeding the TXV?

[Toddbrewster]

Ok, sorry on the "door" confusion, right now the door is not being opened and closed much at all, just enough to restock the beer cooler at the bar maybe once a night, not a big or busy bar, right now all they store in the cooler is case and keg beer until we are sure we can keep the temp in the 38-42 range. So the door may be opened 6-8 times a day or less at this time. There are no new racks in the cooler, just some on the outer walls of the cooler, most are empty, just some kegs sitting on the floor and case beer on the racks on the wall by the door, t-stat bulb located in the airstream going into the back of the evap, no hot foods are being placed in the cooler.

As far as I know no one else has touched this system since I started it up for them 2 or 3 years ago, at which time I evacuated the system which was out of refrigerant, vacuum held, so I charged to a clear glass, checked sh and sc, and have not done anything to it till now. To my knowledge no one has compromised the charge by mixing refrigerants, not many around here that will do refrigeration or know how, unless its a bigger commercial company from one of the bigger cities an hour away, but I am sure this customer would not be willing to pay their rates.

I have checked the back of the evap and it is 100% clean, the condenser is clean, even blew it out with air to be sure.

Didnt want to pull out the 409a and switch to 414b, I dont have 414b and have no accounts with 414b right now, but I do have a cylinder of 409a which is pricey, and thats what the cooler had in it originally.

As to the load caulc. I will need to measure the box and get the evap. and condenser info this week, and see if they are sized correctly, I have wrote the info down, but cant seem to find the condenser info right now. I don't remember what the amp draw was in relation to the nameplate amps, but my liquid pressure was 165#/108F with a liq. temp of 99F, suction was 30#/36F evap. outlet temp was 40f suction temp at the compressor was 48-51f. Ambient where the condenser sits is 80-85 (located in the basement directly below the walk-in, box temp. was 48f at the time of these readings.

Yes the evap discharge temp was 46f, and as I said i dont remember the amp draw, will re check that this week. The evap. has good airflow, only one evap. fan, coil is clean, when they resealed the box, they lowered the evap enough to slide some insulation above the evap, so the evap is wide open.

The txv is not hunting, it is nice and steady, sight glass is clear, txv is getting a steady solid column of liquid, had 6 degrees of subcooling, added some 409a brought the sc up to 8, but still evap air outlet temp at 46f.

I was set to go back and recover the charge and recharge the system now that the box is close to temp, called the bar and they said the cooler was maintaining a 38f box. Only thing I can think is maybe I was in to big of a hurry, as it was really hot this week all the beer was very warm in the cooler as they had it open while they were resealing the cooler, so when they started the system back up it had a huge load, maybe I was not patient enough for the keg beer and all of the case beer to cool off, and the system was just trying to catch up with the large load placed on it. I still plan to stop back in this week see if its maintaining temp, check amp draw, and get the condenser info and box size to see if the system is sized properly to maintain a 38f box temp.

Thank you for all of the input I greatly appreciate all of the comments, will post the amp draw and m/n of the evap. and condenser, along with the box size, still seems to me the discharge air temp. should have been cooler, I am anxious to get my gauges back on the system, and check my pressures, temps and amp draw now that it has been maintaining all weekend!! :cheers:

[K_Neil]

Had a beer cooler customer that was having trouble keeping the beer cold too. Very old building with left overs from old renovations all over the place.
It was about the third or fourth recheck when I noticed an open door at the other end of the cooler. They added an extra 640 cuft. that they didn't bother telling me about and I got to trusting the customer too much. With the door closed it worked fine. Just another wake up call on customer logic vs common sense.

[cool_tech_llc]

Been using 409 and 39 for many years and very few problems, but that said , on older/weak/ undersized systems, you can run into some issues. Both 409 and 39 run slightly higher discharge pressure/temps.
On an old r-12 based system that can cause problems - especially when ambient temps/humidity raise.
I have run into many old systems that were marginally sized using r-12 and when converted to a different ref. and in extreme temps/hum., the evap. coils tend to ice up.