Leak Testing Daikin K Series VRV

[jedi]

Hi All

Was just wondering if anyone with adequate experience could shed any light on the following:

Have been called out to a fault with a Daikin K Series VRV system R22 Cooling Only. There are 3 casette size 100 connected in total. Client reported that the system was not cooling.

Arrived on site and found no refrigerant in system. Told client that it will need to be leak tested and upon identification repaired re-tested and re-commissoned. Client approved this and started testing. Closed both service valves to isolate condensing unit. Charged system to 300psi g using OFN and within a couple of minutes had lost 50psi g. Leak sprayed all obvious places i.e. flare connections, no sign of any leaks.

Stripped down cassettes to expose coils and TEV and leak sprayed. Still no signs of leak. ON the last coil I checked there was evidence of oil collecting at the bottom, happy days I thought this must be the unit leaking. Disconnected suction and dischage and capped off using NPT fittings and re-tested.... but still loosing pressure. By this time I was beginning to get confused.

Decided to disconnect remaining two units and pressure test the interconnecting piping. This time all ok. Reconnected one unit at a time and each time the pressure would drop, not by much this time, but still dropped.

I asked the client if anyone had recently worked on the system, and they said they think a compressor was changed. Could not see any sign of a burn out drier being fitted on suction though??!!

HAS ANYONE KNOWN OF ALL THE EVAPORATORS ON A DAIKIN VRV (ALLBEIT THREE) TO HAVE LEAKS ON AT SAME TIME????

Any advice or comments would be greatly received.

[Peter_1]

Your client doesn't need to give his approval for leak testing: he's obligated to let you do it according to EN378 (see you're an EU member)

All leaking, I should doubt this.

I should pressure test each indoor unit separately, the interconnecting lines after plugging them and the outdoor unit and see which part drops in pressure.

You will also need a halid torch or even better, an electronic leak checker IF there's still some R22 on the system.

You don't need to see a suction line drier because a compressor was changed.
I should especially look to the work the other techs had done. Your client must give you precise information about what they have done, it will save him and you costly time.

[Brian_UK]

Isolating the outdoor unit does not provide two sealed sections.

Early units were prone to leaking through the service valves I believe.

[frank]

Have been called out to a fault with a Daikin K Series VRV system R22 Cooling Only. There are 3 casette size 100 connected in total. Client reported that the system was not cooling.

Arrived on site and found no refrigerant in system. Told client that it will need to be leak tested and upon identification repaired re-tested and re-commissoned.

Good advice to the customer.


Closed both service valves to isolate condensing unit.

Why do this? Are you sure at this stage that the leak is on the pipework and indoor units?


Charged system to 300psi g using OFN and within a couple of minutes had lost 50psi g. Leak sprayed all obvious places i.e. flare connections, no sign of any leaks.

Go back to basics. Pressure test upto 150psig and hold - then see if you have any pressure drop. This will show up any large leaks and prevents wasting OFN. If no pressure drop is found after 10 minutes then raise the pressure upto 250psig and hold. This will find smaller leaks. If this doesn't show any leaks then proceed to raise the pressure up to 350psig, and finally upto 400psig. This should expose any leaks in a R22 system.


Stripped down cassettes to expose coils and TEV and leak sprayed. Still no signs of leak. ON the last coil I checked there was evidence of oil collecting at the bottom, happy days I thought this must be the unit leaking. Disconnected suction and dischage and capped off using NPT fittings and re-tested.... but still loosing pressure. By this time I was beginning to get confused.

Decided to disconnect remaining two units and pressure test the interconnecting piping. This time all ok. Reconnected one unit at a time and each time the pressure would drop, not by much this time, but still dropped.

If you disconnect the fan coils from the system pipework, how are you leak checking the joints after you re-connect? Surely these will need re-testing for both strength and leakage after?
You are possibly making more joints subject to leaking in the future as you have reworked them and you are also making much more work for yourself.

My advice would be to remake any flares that you have disturbed, open up the outdoor service valves and then carry out a thorough pressure test, in stages. As you progressively increase the ofn pressure you will 'hear' the leak, but you must look carefully at every joint along the system.

[Peter_1]

As said before, pressurize in sections and see what section drops in pressure.
I do it the same way as Frank described to avoid waste of OFN.
We even pull first a vacuum with a new install to see if we haven't forgotten a brazing or a flare.

[jedi]

Hi Guys and thanks for all the good advice.

Frank, I understand your concern about potentially making more leaks from disconnection etc, but as I was unable to trace the leak, I was scratching my head and as such thought the only logical way forward was to break the system down. But to answer your question after reconnecting the piping I did strength, pressure and leak test the connections and satisfied myself that there were no further leaks as I was fully aware that I would probably be chasing my tail.

Guys correct me if im wrong but an electronic leak detector will only work if there's refrigerant in it right?? This is what I understood so have not even bothered with it, and have stuck with using soapy water.

Brian I take on board what you say about the service valves and will check tomorrow. Would you recommend that I disconnect the piping before doing this???

[jedi]

Hi Guys and Gals

Just an update.

Basically boss came with me today as he was a bit dubious about all three units leaking..

Long story short, separated all three evaporators and leak tested individually... result.... all three leaking

Tested interconnecting piping... no leaks... Tested condensing unit.... no leaks.

Boss said he wouldn't have believed it if he had not seen it with his own eyes....

[Brian_UK]

Thanks for the update Jedi.

Was it the coils or something else ?

[jedi]

Hey Brian

All three of the leaks are on the coils!!

Went to another site to leak test a Daikin VRV R22 system the other day. "Oh here we go again" I thought. Thankfully for my own self confidence I found the leaks straight away in the condensing unit!!!

Repaired the leaks and left site with a huge smile upon my face!! I was soooo glad I didn't have to re-live the nighmare!!!