Mitsubishi Gas leak? PURY P250 YGMA

[robin r33 gtr]

I think you must cut the system into sections(i.e.) pressure test the condenser on its own, isolate each fan coil unit from the BC box and pressure test each unit with the associated flow and return pipe work and pressure test the bc box on its own. I have found a few leaks in the bc box solenoid valve heads. once you take the pc board off the bc box you can get to all the solenoid valves and really appreciate what the bc box does.

I cannot see the point in cutting the system into sections if it is holding pressure for 4 days.

If there is also dye in the system it should show a leak by now.

Even loosing that much refrigerant a few times with no dye would show signs of oil.

Can you get to all of the pipework?

Have you found all the units on that system and not left one out hiding in a cupboard or on another floor as I have seen this before.

[Goober]

What's happening with this job? Did ya find the leak? Huh? Huh? I think movie rights are being sought for the telling of this story, Brad Pitt being lined up for the starring role.....

[Suffolk Fridge]

come on guys i am itching to know where this leak is now.....

[marc5180]

Hi sorry i haven't updated but as of yet we haven't found the leak but.....

We went back to site and recovered the refrigerant that we had put in and found that it had lost some.

Against what some people suggested, we cut the system up into sections and pressure tested, starting with each indoor unit. Again there was no fall in pressure.

Next we cut the flared connections at the BC box and tested the pipework and the condensor.

We left it for a few days and went back and found the pressure had dopped 10 bar.
So now finally there is signs of a leak.
All i can think is that by running it has disturbed the seal/hole/bend/leak (wherever it's leaking from) and it is no showing signs of a leak, which as you can imagine is great news for us.

We split the condensor and pipework into sections yesterday to prove wether it is the pipework or the condensor that is leaking and i will be going back on tuesday to check it.

If it is found to be the pipework then i will have to seperate the pipework into sections as there is not much access to it. At least this way i should be able to narrow it down rather than ripping all the ceiling down to check the pipework but it is going to take time.

The customer is aware that it is going to take time now but at least now there is light at the end of the tunnel.

I'll update when i find anything more.

Thanks guys

[1torr]

This is better than hwo shot JR

[airconadam]

The leak has now been found am sure marc will be along shortly with the details and maybe a pic.I will keep you all in suspense for now,untill marc posts

adam

[robin r33 gtr]

I have been checking everyday for the answer.

[Goober]

Oooooooooh! The Suspense! The Suspense!

[marc5180]

Went back to site Wednesday and found that the liquid pipework from the condensor to the BC box had lost pressure. Both the liquid and suction had been cut at the BC box and at the condensor so each pipe was being tested individually.

Knowing that the leak was on the liquid i cut the pipework again and braized in 1/4 schraeders to test both sides of the pipe. 1 side was testing from the 3rd floor down and the other was testing the 3rd floor and onto the roof.

I returned the following day and found the piece that was going back onto the roof had lost all its pressure so i knew it was somwhere on this pipwork.

I cut all cable ties off and unclipped the pipework and began stripping off the lagging to check all joints but couldn't find anything.
I traced it back as far as i could then it disappeared through the wall. I went back onto the roof and checked the pipework there but again nothing. I noticed that it disappeared through some cladding and into a roof void to which there was no access and there was about 30m of pipe inside somewhere.

I spoke to the manaager and explained that we needed to get in there so we began to try and take the cladding off. (see pics)

As soon as we had the cladding off the first thing i saw was the pipework then i noticed oil and UV dye everywhere.

We climbed inside and saw that the pipewas was resting on the head of a nail that was sticking out of a joist by about 5mm.

All i can imagine is that over time the pipework has been rubbing against the nail and caused it to wear the coper away.
The hole in the pipework was quite big about 3mmx5mm and the nails head was wedged inside the hole.

I should have took a picture of the nail but didn't. The pics are where the pipework was and getting ready to braize it up. Notice the oil all around and the uv dye if you look closely.

[AbsoluteWDJ]

Went back to site Wednesday and found that the liquid pipework from the condensor to the BC box had lost pressure. Both the liquid and suction had been cut at the BC box and at the condensor so each pipe was being tested individually.

Knowing that the leak was on the liquid i cut the pipework again and braized in 1/4 schraeders to test both sides of the pipe. 1 side was testing from the 3rd floor down and the other was testing the 3rd floor and onto the roof.

I returned the following day and found the piece that was going back onto the roof had lost all its pressure so i knew it was somwhere on this pipwork.

I cut all cable ties off and unclipped the pipework and began stripping off the lagging to check all joints but couldn't find anything.
I traced it back as far as i could then it disappeared through the wall. I went back onto the roof and checked the pipework there but again nothing. I noticed that it disappeared through some cladding and into a roof void to which there was no access and there was about 30m of pipe inside somewhere.

I spoke to the manaager and explained that we needed to get in there so we began to try and take the cladding off. (see pics)

As soon as we had the cladding off the first thing i saw was the pipework then i noticed oil and UV dye everywhere.

We climbed inside and saw that the pipewas was resting on the head of a nail that was sticking out of a joist by about 5mm.

All i can imagine is that over time the pipework has been rubbing against the nail and caused it to wear the coper away.
The hole in the pipework was quite big about 3mmx5mm and the nails head was wedged inside the hole.

I should have took a picture of the nail but didn't. The pics are where the pipework was and getting ready to braize it up. Notice the oil all around and the uv dye if you look closely.

Nailed it! Well done.... There great systems VRF/VRV but a pain in the backside and not to mention time consuming, when your looking for a small leak!

[robin r33 gtr]

How many days will you be billing for that job? At least you got there in the end.

[laf100]

Good work Marc.

[pie man]

Nice one that was a great read, glad you solved it!

[Brian_UK]

Well done Marc, the customer should be happier now with less callouts to come.

We all have 100% hindsight but don't you kick yourself for not pushing harder to get at the invisible pipes earlier ?

[marc5180]

I don't know what's going to happen regarding the cost of the job, thats not up to me.

The customer is very happy that it's fixed. This is the prime example of why access is needed to pipework and indoor units and BC boxes and this is why it has taken so long because there was no access.

I hope i never see another leak as long as i live.

[rude]

Well done!! i hate leaks like that where you cant find them, but u persisted and it worked out!

[Brian_UK]

I can see the headlines now in the trade mags.

Student of the Year finds hidden leak.

Global Warming risk removed.

[Suffolk Fridge]

well done mate sounds like a job well done, one for the memory banks hey?

[marc5180]

I can see the headlines now in the trade mags.

Student of the Year finds hidden leak.

Global Warming risk removed.

I wish, sadly i was the runner up
but yes the global warming risk has been removed

[jdunc2301]

and thats why im always mysteriously ill or busy when a VRV/VRF comes in showing signs of SOG

[sinewave]

Still strange though why the system was continualy holding OFN pressure testing levels over days with such a big hole?

[Contactor]

Phew, get some sleep now then...

[al]

Still strange though why the system was continualy holding OFN pressure testing levels over days with such a big hole?

Cos ofn has a larger molecule size i think??

al

[marc5180]

But it was tested with OFN and helium and showed no signs of a leak until we ran it up again.

[nike123]

We had thought that someone could be tampering with it so we had marked the caps on the condensor.

It took 2 weeks before we were called back to it and that time is up next thursday. I have my fingers crossed and everything else for that matter
Only time will tell now.

Last fall I was commissioned one MHI VRF, and portion of pipes was buried in floating concrete floor (estrich). Floor is made from wooden beams and planking on which I layed pipes from distributor to floor standing FC. Than I made pressure and leak test and leaved pipes under pressure. Than builders are poured concrete layer at insulation above planking (and pipes).
Cople month later I was at site to mount Fan coils and found no pressure in pipes.
I pressurised pipes and after lot of searching found nothing. Then I decidet to go back in midle of the night when no one is in builiding and sorounding is quiet. And after lot of walking like ghost, I finaly found hardly to hear hissing above my head in one room. Hissing is so quiet that you need absolute quietnes in sorunding to be able to hear it. That is why I conducted my search in midle of the night, no mater what object location is on one of Islands and far from city noise.

Then I localised place where hissing is coming and found that hiss coming somwhere from above where pipes, which feed floor mounted FC in room above, are layed.
Next, I needed to demolish concrete above from FC to point where hissing is heard.

After some diging I finaly found that screw (3,5 X 35 mm Knauf screw, very sharp tip) which holds flexy ducting holder from ventilation mounted below is screwed in one of pipes wich feed FC and that on that place I cannot separate pipe from floor. Hising is realy quiet, and only when I unscrewed screw hising has amplified somewat.

When I checked how much N2 pressure I lost during searching (whole day and main portion of night) i found that it drop less than 1 bar, which you could easy assign to pressure drop becaouse of temperature change.
Therefore, I considered myself wery lucky guy.

Finaly, I cut and and repalaced portion of pipe to FC.
Later it was pressurised again and I pronounced piping healty after it is been at right pressure (corrected for temperature change) for 7 days.

Nedless to say that, when I mounted pipes, I strictly said to construction supervisor, that NO ONE CANNOT SCREW NOTHING in floor or in ceiling without my supervision (I photographed whole instalation).
And best ting is, that guy from team which I supervised in ventilation mounting and whome I explained that he cannot screw anything in planking, only in beams, is rensponsible for that "scr ewing" and that he (of course) did not mention to anybody that he done that crapping.

I hope someone could learn something from this example. I certanly did!

[marc5180]

That sounds like a nightmare, having to demolish the concrete to get at it as well.
Rather you than me

[ukcragrat]

It just proves that this job is never boring, frustrating sometimes, but in this case very rewarding. Well done Marc.

[1torr]

I had a 11/8th suction ball valve leaking from the body where its screwed together on a Sanyo once. It held ofn at 41 bar,sprayed with leak spray no leak. Put 8 bar R410a in and bubbled up straight away.

[jteixiera]

I think you must cut the system into sections(i.e.) pressure test the condenser on its own, isolate each fan coil unit from the BC box and pressure test each unit with the associated flow and return pipe work and pressure test the bc box on its own. I have found a few leaks in the bc box solenoid valve heads. once you take the pc board off the bc box you can get to all the solenoid valves and really appreciate what the bc box does.

i did mention to cut the system apart a few weeks back.

well done got their in the end

[fridgemagnet]

Well done mate for finding the leak should help keep the hole above my head (here in NZ) a bit smaller for a bit longer.


One thing you guys might want to considder is UV dye is not permitted in city multi units (any mitshubishi for what thats worth) reason being is causes plating on the compressor bottom bearing when used with R407b and R410A. end result complete failure of compressor and the next and the next .........

Might be time to read those manuals before we add aditives to systems.
I was involved as an independant engineer for mitsy on why thy had a string of commpressor and diode fails on a city multy entire waranty claim got declined du to UV Dye in the system. The buildup causes continous high current draw wich is just under the safe limit of the system diodes when the compressor seizes the time delay is too long to protect the diodes wich were basicly running at their max the entire time, normaly they are overrated by 35% to prevent this from happening.

Get an infrared sniffer its a God sent tool they detect leaks as small as 3g per year dont get affected by wind like the old cold and hot cathode sensers. Next leak you have and find in one day with your brand new IR Sniffer you can thank me

[dellapureneed]

Oh hell, I think I've got the same type of problem about to occur!!
So far my system hasn't been ran up, it is only 16 units of mix between wall mount & cassettes. All pipe work is internal to/from Box & is available to get at. Except where it follows through bulkhead to studding wall for wall mount & to ceiling bulkhead for cassettes as this is now decorated & there are only 2 brazed joints above per room. All the flare joints were made off good, so I was told & brazed joints were alledged to be good too!. The pipe was ran in coils from box area down a corridor & peeling off left right per set to each room. The longest is 30 metres & no other joints or additions were made & it is only 1/4" & 1/2".
The pipes serving box are ready for final penetration to plant deck area & as no condenser is on site. I have closed off the 2 serving pipes to the box & put schraeder access on both. I introduced OFN slowly & checked 5bar-10bar-15bar-20bar-& up to 41.5bar. It took a very long time than normal to get up to 41.5bar but no leak apparant heard in the rooms at access points to flared connections! building was vacant & no noise disturbance.
1 hour with whole lot capped & sealed a drop to 40bar, so I topped up back to 41.5bar thinking there would be some settlng to equalisation.
1 hour later drop to 40 bar again & no temperature drop that day or opening doors or windows to rooms etc etc.
Next morning 18bar!!!! OH DEAR leak imminent.
checked all flares with bubble test nil found
My thoughts are that the very limited space that the 'design' had to install the CMB Box has 16 units sets of pipes all brazed all sweeping under the box then up towards port connection stubs. So I can ony see if the leak is inside this box then oh hell it will all have to be disconnected to get inside & cap off all 32 stubs & re test. I know for a fact this box had OFN factory shipped inside & was still there when 1st cut off retaining cap.
Now only assuming the pipes were actually brazed up well & the flares were good, then if these prove still leak tight & the box is proven good too.
Can it then be a pipe fracture in a bend or a split in the tube? this would be less of a chance I know but has occured before with even quality pipe!
I do hope it can be found easy I may have to ask the builder to remove sections of MF ceiling around the corridor where the likelyhood of bends are & cut the armaflex lagging & have a good listen and bubble test.
If this still cant be traced then I might have to look at the indoor units themselves!
It may be more a suspect than you think! I do suspect some heavy handed manipulation by the lads on the wall mount pipe tails to exit them 180 degree back in the opposite direction. This has been found before with the pipe from manufactured as it connects to the coil, once reversing of the bend & even though the 'spring' stops most over zealous collapsing/crushing it could be just one weak point or braze there that could be the leak failure.
I have found on a wall mount VRV from Toshiba that the brazed on brass flare union to pipe was a 'dry' joint & leaked as low as 5bar!! That was supposed to have been tested at factory? Unlikely. We re brazed it & was fine then.

Any comments welcome
Dellapureneed.

[marc5180]

If the system is loosing pressure then with regards to actually finding the leak then this can only be a good thing.
The quickest way I have found to find a leak on these systems is to pressure test the whole system as you have done and check all indoors/BC box flare nuts etc.

If no leak found then split the system up into sections ( I know it's a pain but in the long run it's quicker)

I'd separate the consensor from the pipework, also if the run to the bc box is quite far then test this then test the BC box with all 16 units.

If it drops with the 16 units on the you will have to begin separating the indoorsas well.

Good luck

[martinw58]

have had leaks in side bc box where pipes conect on big pipe