Leak detection

[Tennhvac]

I have to go look at a split unit on monday that has been topped off on 410a three times in three months by another company. I was called because he cant find the leak. The unit is at zero psi. I havent done a whole lot of leak detection work and my question is if I pressurize the system with nitrogen how much 410a can I add for my sniffer to pick it up and what pressure should I pressurize it to?

[ksefan]

If it is that bad you might hear it. Depending on the detector and how close you can get to it, maybe a few ounces to a lb.

[Zamoramax]

If its that bad. Find the oil. My moneys on the flares. Post the results.

Sent from my SM-N960U using Tapatalk

[pecmsg]

5 - 10 PSIG refrigerant. N2 start at 100 leak check, 200 leak check 600 hear the leak

[Unlimited1]

0psi is an obvious leak. Seen many at the evaporators but I also use UV dye to see it..it will also show it in the drain as confirmation..

[YOUNG FROSTY]

If its that bad. Find the oil. My moneys on the flares. Post the results.

Sent from my SM-N960U using Tapatalk

Flares, as in mini split? OP said "split unit", not sure if he means a mini split (flares), or a split system (no flares). I've never heard the term "split unit" lol.


@ the OP:

Usually the first thing I do for leak detection is just pump in the nitrogen. I usually ease it up to somewhere around 150-200 psi in a case like yours. A leak like this is definitely large, possibly large enough you could hear it. Start at 200 psi and get your Big Blu spray bottle out and spray all the braze joints. LL filter drier, outdoor unit, indoor unit. Look for the bubbles ALL AROUND each braze joint, use a mirror if necessary. Even a teeny tiny leak will bubble up like crazy. Also spray your service valves, remove the caps off the top and spray those (where you put your allen wrench to open/close the refrigerant). Also, spray into the schrader cores, sometimes a schrader will leak. I had a mini split one time that was leaking out the schrader straight out the factory.

If you've done all this, then the leak is most likely in one of the coils. This may require the use of a leak dye and a UV light, which means scheduling a later appointment to come back after it has circled around the system for a week or two.

If it's a mini split and not a split system, I would spray your flare nuts first thing, and hope and pray to sweet baby Jesus its the one on the outside and not behind the indoor head (pain in the ass)

[Zamoramax]

Flares, as in mini split? OP said "split unit", not sure if he means a mini split (flares), or a split system (no flares). I've never heard the term "split unit" lol.


@ the OP:

Usually the first thing I do for leak detection is just pump in the nitrogen. I usually ease it up to somewhere around 150-200 psi in a case like yours. A leak like this is definitely large, possibly large enough you could hear it. Start at 200 psi and get your Big Blu spray bottle out and spray all the braze joints. LL filter drier, outdoor unit, indoor unit. Look for the bubbles ALL AROUND each braze joint, use a mirror if necessary. Even a teeny tiny leak will bubble up like crazy. Also spray your service valves, remove the caps off the top and spray those (where you put your allen wrench to open/close the refrigerant). Also, spray into the schrader cores, sometimes a schrader will leak. I had a mini split one time that was leaking out the schrader straight out the factory.

If you've done all this, then the leak is most likely in one of the coils. This may require the use of a leak dye and a UV light, which means scheduling a later appointment to come back after it has circled around the system for a week or two.

If it's a mini split and not a split system, I would spray your flare nuts first thing, and hope and pray to sweet baby Jesus its the one on the outside and not behind the indoor head (pain in the ass)

True. I'm working with mini splits right now and had it on the brain I guess... either way oil travels with the refer. There for with a leak that big, you will find oil somewhere. Sometimes it's not as obvious as 15W-40 puddled on the ground. But you should see saturated copper.

Sent from my SM-N960U using Tapatalk

[YOUNG FROSTY]

Whats refer? Reefer? I usually save that nonsense for the weekends

[Unlimited1]

back in my day reefer was an herbal supplement when you got bored, lol

[Tennhvac]

Alright just spend 2 hours bubble testing at up to 250 psi nitrogen checked lineset evaporator coil and condenser coil no signs of oil and no big or small blue bubbles. Is their something I'm missing. Should I pull a vaccum and recharge this unit and monitor it.

[glockdoc]

I’ll throw this method out there. Just finished up a split system that had a major leak. I pressurized the sys to 100 psi and then shut both service valves and then went back the next day. Checked the psi before opening the valves, psi was holding. Opened valves and got a psi drop. Fogured leak was on the condenser side of valves. Leak was on the hot gas line coming out of the compressor-the sound suppression boot that covered the compressor had rubbed a hole into the copper line.

[Zamoramax]

I’ll throw this method out there. Just finished up a split system that had a major leak. I pressurized the sys to 100 psi and then shut both service valves and then went back the next day. Checked the psi before opening the valves, psi was holding. Opened valves and got a psi drop. Fogured leak was on the condenser side of valves. Leak was on the hot gas line coming out of the compressor-the sound suppression boot that covered the compressor had rubbed a hole into the copper line.

I woulf try his method. So you could know which side the leak is on.

Sent from my SM-N960U using Tapatalk

[glockdoc]

In my case (rental), I had the luxury of time where I could go back the next day. I was sure glad it was not on the evap side since air handler was in a low crawl space doing a belly crawl.