HVAC guy Needs help with Hussmann PLEASE :)

[a_s_m]

Hi guys ... I'm looking for some insight into what the hell is going on with this hussmann system I looked at yesterday. Keep in mind that it has been running for 14 years and this is the first problem they have had with it.

What I have is a 3 serparate hussmann NRCV Glass door coolers. Two 5 Doors and a 2 door. They are all connected to one single Bohn Condensing unit(r-22). The label in the coolers say r-502 but its been converted to r-22 I guess.
All the TEV's are r-22. Its in a beer and wine store and its all loaded with wine.
I can see that these were originally set up as Ice Cream freezers. So when they installed them here they didn't connect any of the wiring or controls, just wired in the evap fans and lights. Running +30 box. Off Cycle defrost.

Everything has run fine for 14 years, the other day the defrost timer in the bohn condenser died during offcycle defrost and everything warm up. I went out and replace the defrost clock. Came back the next day and the two 5 door coolers were at +30 but the 2 door was warm around +60.
Opened it up and had 60 degrees superheat.suction pressure right at the coil was 25psi... seemed pretty starved Tried adjusting the tev but that didn't work. So I went out and picked up a new one, the same that was there. Sporlan Q body... BQE with a AAA cartridge and a kt-43VC powerhead. Pumped it down, swaped in the new tev. Pulled a 300 micron vac etc etc. And still the exact same thing is going on. Could it be that this cooler can't pull down with warm wine stocked in it. Can someone give me a few ideas ? I'm a refrigeration mech but mainly on the HVAC side... so I'm trying here haha. Does anyone know what the BTU rating of the evap coil is in this NRCV 2 door? Also what my TEV capacity should be? The AAA cartridge looks like its good to about 4000 btu's.

Thanks for any help in advance!

[icemeister]

Here's the Hussmann info on that case:
http://www.hussmann.com/Discontinued..._0345913_E.pdf

[a_s_m]

Thanks Icemeister ... I actually have already printed that off but it doesn't really give me any of the info I am looking for ... just installation and electrical.

[beenthere]

Moved to Refrigeration and ice making

[jpsmith1cm]

How is your charge?

[Wheelbaron]

I might think about puting in a sight glass before each unit to make sure you are getting good liquid to each.

[a_s_m]

The charge seems ok . The other two 5 door coolers are at temp and working fine. The Sight glass on the bohn condensor is bubbling, but it 40 degrees outside and the headmaster is bypassing hot gas into the liquid line to keep the headpressure at about 180 PSI. I blocked off the condensor with cardboard to raise up the headpressure so it would stop bypassing and the sightglass cleared up. I would also assume that if it was low on charge that all the cases would be affected.... Any further ideas? Could i possibly have put in a bad TEV?

[Phase Loss]

The charge seems ok . The other two 5 door coolers are at temp and working fine. The Sight glass on the bohn condensor is bubbling, but it 40 degrees outside and the headmaster is bypassing hot gas into the liquid line to keep the headpressure at about 180 PSI. I blocked off the condensor with cardboard to raise up the headpressure so it would stop bypassing and the sightglass cleared up. I would also assume that if it was low on charge that all the cases would be affected.... Any further ideas? Could i possibly have put in a bad TEV?

The headmaster should be bypassing hot gas into the receiver, not the liquid line?

anyway, you do not have enough charge to flood the condenser and still maintain a liquid seal in the receiver at 40* ambient.

leak check, repair as needed.

[a_s_m]

The headmaster should be bypassing hot gas into the receiver, not the liquid line?

anyway, you do not have enough charge to flood the condenser and still maintain a liquid seal in the receiver at 40* ambient.

leak check, repair as needed.

Ok cool I will look into that. But why do you think only the 2 door cooler would be affected by the low charge?

[jpsmith1cm]

Ok cool I will look into that. But why do you think only the 2 door cooler would be affected by the low charge?

Check out the way the liquid line is piped. Think about the inertia of the liquid.

You should see it.

While you are at it, look here for charging instructions.

[Dowadudda]

I might think about puting in a sight glass before each unit to make sure you are getting good liquid to each.

buy yourself an electronic sight glass. there great for stuff just like you mentioned.

[Dowadudda]

sounds low on gas. Your feeding the two 5 doors and not the 2 door. The headmaster in action or not, you should have and need a solid column of liquid.

[a_s_m]

Thanks for all your input! Here's an update... I returned today to find that the case had pulled down to temp without any product in it. Checked my sightglass(bubbles) and then checked the superheat on the 2 door it was still really high at 50 degrees superheat. Low charge it is... what threw me off was that the other 2 cases on that condensor were running fine. For some reason I thought that if the charge was too low that all cases would be affected. So after taking into account all your info and analysing the system it was obvious that it was low on charge. So I topped up the system and set up everything just great. I also found out that the system was not installed 14 years ago. They bought it used (14 years old) and had it installed during summer. SO .... I am assuming that whoever installed this thing started it up in summer and just cleared the sightglass and did not put in the "extra winter charge". I did a quick electronic leak test in each case and the condensor and did not pick anything up. I certainly am not going to make them unload 3000 bottles of wine and tear apart 3 cases to search for a leak that is probably not even there. I let them know that over time we will be able to tell if there is a leak and at that point I must proceed as mentioned above.
The headmaster is also working just fine keeping my head up at 180 psig... it is bypassing into the receiver NOT the liquid line.
I also think what may have set off the chain of events was that defrost clock failing and the cases warming up. It seem that low on charge the coolers may have been able to maintain temp, but as soon as we were asking it to pulldown a product... the capacity just wasn't there.
Thanks again for everything... Great site!

[maints]

It might be about time to replace your core driers too. Can you check for pressure drop across them?

[a_s_m]

It might be about time to replace your core driers too. Can you check for pressure drop across them?

I did check TEMP across them, and there was no change at all.

[jpsmith1cm]

I did check TEMP across them, and there was no change at all.

I've seen driers with 100# across them without a temp drop.

Put the gauges on it.

[Dowadudda]

you better run now. cause if you keep this up, you just might turn into a refrigeration guy.

Great Job. Stay away from my customers.

[a_s_m]

you better run now. cause if you keep this up, you just might turn into a refrigeration guy.

Great Job. Stay away from my customers.

Haha well its a good thing our customers are in different countries. But in all honesty, I think I'll concentrate mainly into the hvac and building controls side of things. That is where I have spent the last 12 years. I don't mind tinkering with product refrigeration from time to time, but it's certainly not my area of expertise! My work is probably only 15% refrigeration, only because the owner has so many friends that own restaurants haha. But Again thanks alot for the insight