Strange Leak On System

Last September I change the full condensing unit on a cold room. System ran up fine, no problems at all. Christmas time the client went on holiday and emptied the cold room and left it switched off. When he came back 3 weeks later and switched it back on, it was tripped on LP. I went down, and sure enough no gas in it. Pressure tested over night and the pressure didn't budge at all. I was thinking maybe the leak could have been from the service valve, as I left my gauges on over night. So I put some of that red dye stuff in, replaced the valve caps with brass flare nuts and bonnets, vacced out and charged. That was mid January. Called into the place about a month ago, Room 2ºC, sight glass full, everything looked good. Client went into Hospital 3 weeks ago, so again switched the system off. Client returned yesterday and again tripped on L.P. I´ve just got back from site. No gas in it again. No red dye anywhere, no oil anywhere.

It´s got me puzzled as to why it only leaks when it´s switched off and why there is no dye or anything traceable? Anyone any suggestions?

Yep, sounds like you've got a leak on that system, only one thing for it - keep pressure/leak testing till you find it. I had one recently of a similar nature, it was the tiniest of leaks on a discharge check valve which took me forever to find. The chiller would fall over after about 3 months of running, and lose about half its charge in that time. I prefer to use the old 'soapy water' leak detector method when looking for small leaks. Happy searching!
Regards, Andy C.

Can you isolate the high and low sides of the system to determine which side the leak is on, my guess is it is on the low side, when the standing pressure is raised. be sure to check the pressure switch bellows for leaks when pressure testing. Split flare nuts at the expansion device are also a possibility. Regards, Andy C.

Have a look at any joints on the low side,it may be hidden within the lagging hiding from you:).

Also have a look at the drain outlet,you might have a leak on the evap and you might see the dye in the drip tray.

I hate small leaks.

Already checked the evaporator and drain. No sign there.

I was thinking it was on the low side too. But if it is on the low side then why does it go all the way to 0 psi. As the system under normal conditions runs with a suction pressure of around 25-30 psi (from memory) and doesn´t appear to leak at all, then I would expect to see at least a little pressure, maybe 20-30psi, left in the system? Can anyone explain that.

The only joints I have on the low side are, the flare connection onto the service valve (I´ve got a feeling it´s here), The L.P. switch and brazed joint on the evap. One thing I forgot to mention is that I replaced the capillary tube onto the L.P. switch last time, as pre-caution.

The bit that gets me is why it looses the charge so quickly when switched off. But when it´s in use appears to keep the charge.

For one why is he turning the coldroom off as this is not normal behaviour :confused: and will cause the gas to leak quicker than normal as the pressure in the evaporator is a lot higher than normal. Tell him to leave it switched on and get yourself a decent leak detector and test with condenser fan jammed to increase the presures good luck

I notice that your location is lanzarote.
Is it hot there or rather how hot does it get.
take the average midday ambient and do a pressure temp comparison.
Are you still surprised of a leak on the low side??
Is there any low side joints that say when running are kept cool / cold.
That when the system is off heat up... say a copper / bronze service valve on the suction.
Non ferrous metals / rotalocs etc move around a lot when subjected to large temp fluctuations..

I sounds to me as if something that is usually low temp low pressure. Is leaking when returned to a non running higher ambient temp situation.
I am assuming because of your reference to the flared joints on the service valve. That the compressor is Hermetic and not a semi- hermetic.
Because if it was the first place I would look would be the Shaft Seal?
Also is there a low side pressure relief valve or bursting plug that weeps???

I hope some of this is of help?
Cheers Grizzly

Could be leak on some place where two different metals are making seal when is hot, and when system is off and cold, seal is loosed due to different thermal expansion/contraction, and because of that, there refrigerant leaking.
Pressurize cold system with nitrogen and concentrate at places with different metals.

Look at Class 3 here and read thru whole manual:
http://tinyurl.com/49fa46

Have you ck the bellows on pressure controls?

Different metals would explain it. I had never thought of that and would explain how a leak could develop on the low side. I may investigate that further.

Currently the suction line is brazed onto the compressor and comes out and bends down towards the bottom of box. It´s not even 200mm long. There it goes onto a valve (steel I think) with three ports. One is capped off with a brass flare nut and bonnet, One I connected a peice of 1/4 copper with gauge fitting (and schreider valve) by flaring the tube, the last is a brazed connection that goes off to the evap (well comes from the evap). So that valve would definitely be a likely source of the leak. Because when operating it would normally be cold. When switched off it would be around 30ºC.

Low pressure switch, I have a spare in the van, I think I´ll change that anyway, as I think that may be the orignal switch on the system now. I can´t remember changing it when I changed the condensing unit. So it doesn´t hurt to change it now.

Lanzarote has been warm for the past week or so, In the 30´s everyday but before that mid to low 20´s for about the last month or so. The fridge is in a basement though, so it´s always warm in there.

Thanks for the suggestions. And thanks Nike for the manual, I´m going to have a read through that now.

One other thought - is someone stealing the gas when the boss is away ?

Quote:

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Originally Posted by Brian_UK

One other thought - is someone stealing the gas when the boss is away ?

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NOW WHERE DID THAT 1 COME FROM BRIAN??
I HAVE HEARD SO SAY OF AMMONIA BEING STOLEN TO BE USED TO CRACK DRUGS!!! ONLY IN AMERICA!!!

BUT RANDOM GLUE SNIFFERS IN LANZAROTE?

GRIZZLY

Quote:

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Originally Posted by Brian_UK

One other thought - is someone stealing the gas when the boss is away ?

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Maybe some terrorist making Fosgen now ;-)

Quote:

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Originally Posted by nike123

Maybe some terrorist making Fosgen now ;-)

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AS THEY SAY IN UK.
NOW THAT'S MUSTARD!!!!:)

Its been a slow night honest.
grizzly

No joke about stealing gas. Had three units in basement and Friday all is well. Monday morning brings 911 call all units down. Finall put lock heads on valve stems. Stops the " leaks " right away. Also used u/v dye in spray bottle on valve caps. Black light showed dye on door knobs. They will steal anything. Feisty

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Originally Posted by FEISTY

No joke about stealing gas. Had three units in basement and Friday all is well. Monday morning brings 911 call all units down. Finall put lock heads on valve stems. Stops the " leaks " right away. Also used u/v dye in spray bottle on valve caps. Black light showed dye on door knobs. They will steal anything. Feisty

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UNREAL!
Although I suspect there will be quite a market in gases particularly R22.
Once all Regs bite over here in Uk.
Cheers Grizzly

Hi Airfresco,

Check valve stem seal is greased and done up reasonably tight and gasket is in place on stem cap.

Another area to check is compressor 'fusite' terminal area where elelctrical connections pass through into compressor.

Is compressor semi-hermetic or hermetic?

Remember that nitrogen is denser than *****, so if it is a tiny leak, try filling the system with some ***** and then use nitrogen to elevate the pressure...

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Originally Posted by Tycho

Remember that nitrogen is denser than *****, so if it is a tiny leak, try filling the system with some ***** and then use nitrogen to elevate the pressure...

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Adding a trace element is a brilliant way of finding the leak.
Although not strictly allowable within the UK. anymore!
Cheers Grizzly

Good job I´m not in the UK then;)

Comp´s hermetic.

I went to site yesterday. Replaced The L.P. switch with a brand new one. I don´t know why I did it like this, but L.P. switch connected to the suction line by the capillary tube brazed into a short piece of 1/4 copper, which was flared onto another piece of 1/4 that went onto the suction line on a T. Flare connection is now gone and the capillary is brazed straight onto the short piece of 1/4 and straight onto the suction. So that´s one less possible place to leak.

I cut the service valve out. A bit drastic I know, but I got a feeling that´s where the leak is. So now the suction goes straight onto the compressor. There´s no way to pump the system down, but I put a 1/4 gauge fitting t´d into the suction, so it can still be vacced and charged.

So the only connections that aren´t brazed now are the drier/sight glass, the discharge onto a service valve on top of the accumulator and the TXV. One thing I did notice is when I cut the suction line there was dye in the pipe or any the bits that I removed, so I don´t know where thats gone. Maybe I did something wrong with that.

It´s on a pressure test now, so I´m going to check it in the morning, hopefully it´s Ok and I can vac and charge.

Quote:

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Originally Posted by airefresco

Good job I´m not in the UK then;)

Comp´s hermetic.

I went to site yesterday. Replaced The L.P. switch with a brand new one. I don´t know why I did it like this, but L.P. switch connected to the suction line by the capillary tube brazed into a short piece of 1/4 copper, which was flared onto another piece of 1/4 that went onto the suction line on a T. Flare connection is now gone and the capillary is brazed straight onto the short piece of 1/4 and straight onto the suction. So that´s one less possible place to leak.

I cut the service valve out. A bit drastic I know, but I got a feeling that´s where the leak is. So now the suction goes straight onto the compressor. There´s no way to pump the system down, but I put a 1/4 gauge fitting t´d into the suction, so it can still be vacced and charged.

So the only connections that aren´t brazed now are the drier/sight glass, the discharge onto a service valve on top of the accumulator and the TXV. One thing I did notice is when I cut the suction line there was dye in the pipe or any the bits that I removed, so I don´t know where thats gone. Maybe I did something wrong with that.

It´s on a pressure test now, so I´m going to check it in the morning, hopefully it´s Ok and I can vac and charge.

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Good Luck.
And thanks for keeping us all updated as an experienced poster yourself. You must allready know how annoying it is, for people not to respond !
Grizzly.
PS, just a thought but you say you added the dye prior to vacuuming out the system.
Seems a strange way of doing it? maybe just maybe that has something to do with where the dye has gone?
What do you think?

I might be wrong about which way round I did the dye, i´ve slept since then. I did whatever it says on the bottle.

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Originally Posted by airefresco

I might be wrong about which way round I did the dye, i´ve slept since then. I did whatever it says on the bottle.

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No Problem.
Just that I hate unsolved problems.
Cheers Grizzly:)

Dear airefresco

Is it a semi, hermetic (sealed) or open type condensing unit?

Have had a couple of leaks on condensers that are hard to pick up until you bump the system right up with dry nitrogen.

hi i have had gas loss through the electrical terminal connections on the compressor worth a check

whoever said the leak was on the evaporator wins a gold star. The bloody thing tripped again last week, so I took the evap out and pressure tested that independently from the condenser. Left it a couple of days. Evap lost 80psi, condenser lost about 1 or 2 psi, but i´m putting that down to me taking the guages off a couple of times.

The leak was actually on the top of center run inside the coil. It was absolutely tiny, the copper looked fine, but the leak spray said otherwise. I would´ve never of found that with the evap in place. Bit of bugger to fix, but it´s been on a pressure test for 4 days now and only lost a couple of psi, but I have been putting gauges on and off everyday, so I think that´s an acceptable amount to loose.

My theory is that when the evap iced up a bit, it was sealing the leak. When the client switch the fridge off, ice melts and system leaks, dye and oil wash away with the condensate. Anyway thanks everybody for your help.

Quote:

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Originally Posted by Grizzly

Adding a trace element is a brilliant way of finding the leak.Although not strictly allowable within the UK. anymore!

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You're right, what about adding Helium? Are there portable leak sniffers available for helium, price range same as we use now for HFK refrigerants?.
Flaring 1/4 is also no longer allowed.
And a safety button inside the cold rooms (>10 m³) to switch of cooling and fans, emergency lights on the floor(!!) on a separate electrical circuit

Why is flaring 1/4 not allowed?

According to EN378/2 - 6.2.3.2. flaring not allowed for copper with a diameter less then 9 mm.
Surprisingly that the AC manufacturers haven't seen this yet.
Should be a good idea, everything soldered on AC's, all the DIY'ers can't install any longer their AC's.

TBH I think that is a stupid rule. 9/10 times, in my experience, when there´s been a leak on flare, it´s been on the suction flare, which is normally 3/8 or larger. Have I missed the point here? However, I do agree that it will make it much harder for the DIY´ers, which is a good thing.

Quote:

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Originally Posted by airefresco

TBH I think that is a stupid rule. 9/10 times, in my experience, when there´s been a leak on flare, it´s been on the suction flare, which is normally 3/8 or larger. Have I missed the point here? However, I do agree that it will make it much harder for the DIY´ers, which is a good thing.

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This is not a rule but an European law which is of course completely different.
If you ask my opinion, indeed a stupid rule.

As always, probably made by someone without practical experience.

The Dutch translation of this EN378 is even more hilarious: in the original English version you can read: Asbestos may not be used which is for me that it is forbidden to use asbestos. They translated it in Dutch as Asbestos must not be used which says that it can be used.
Am I wrong?
And then the EN378 lawyers had then to translate new words for them and invented new Dutch words for it.
Liquid hammer is translated as water hammer.

Found several wrong translations.

people sniffing refrigerant when no one is around?

master-bilt ice cream marchandaiser ... evap. fan blower has it or not ..? some one knows ..?