GT heat pump - evap coil pinhole leaks

stevehull · 08-27-15, 08:51 AM

I just got a functioning closed loop GT heat pump for $100. But here's the catch . . .

Leaking gas from somewhere and the HVAC guys think it is in the evaporator coil. Apparently this particular unit has tiny "bubbles" in the coil that are attacked from the inside (that is what I was told). They suggested some kind of liquid that can be put into the system that "plugs" tiny pinhole leaks. Not a great solution (reminds me of using that crud in car radiators . . . ).

The unit is a 2.5 ton, single stage Florida counterflow unit. It was set up for closed loop, so I got the circulation pump as well. A beautiful coaxial coil inside and the scroll compressor works great. I saw it working.

The owner got tired of putting in a couple lbs of R22 every six months and the unit is about 15 years old.

Ideas on plugging leaks? The alternative is to go with a generic coil as the specific OEM replacement from Florida is almost $1000.

TIA.

Steve

jeff5may · 08-27-15, 11:54 AM

What is the unit configuration, water to water, or water to air, or water to line set? Pics would be awesome.

If the compressor and/or water pump work, you got your money's worth. Everything else that works is a bonus.

stevehull · 08-27-15, 01:55 PM

Jeff,

Water source to air with desuperheater for hot water tank.

Steve

doug30293 · 08-27-15, 05:39 PM

Quote:

Originally Posted by stevehull

Leaking gas from somewhere and the HVAC guys think it is in the evaporator coil. Apparently this particular unit has tiny "bubbles" in the coil that are attacked from the inside (that is what I was told).

That sounds like formicary corrosion. It is a big problem with R410 systems. I've never heard of it on an R22 system. About the time manufacturers switched to higher pressure R410 they also started using thinner wall tubing to increase EER (and profit margin). It didn't work. The HVAC industry is still in plausible denial.

You are right that goop in the coil is not a solution. I suggest finding another coil - if that is indeed the problem. It might be a slow leak around the glass seal on the compressor. I've seen a few of these.

AC_Hacker · 08-27-15, 07:00 PM

Quote:

Originally Posted by stevehull

Ideas on plugging leaks?

Does it have any R22 in it?

If yes, salvage the R22, vacuum it down to a deep vacuum, then fill it with R290, and do the flame test.

If no R22, vacuum it down to a deep vacuum, then fill it with R290, and do the flame test.

Once you know where the leak(s) can be found, use your well-honed brazing skills and braze up the leak(s).

If Xringer can do it, maybe you can too.

Otherwise, call a local HVAC tech to come out and fix it for you.

-AC

stevehull · 08-27-15, 08:12 PM

Why not just use an R22 "sniffer" to detect the leak right now? And yes, it has R22 in it right now as I saw it running before it was taken out. I think I can borrow one. Or, I could put in fluorescent dye and look for leaks.

I actually helped with the labor of getting this 200+ lb thing out of the closet . . .

I need to call as the HVAC guys may have used a "sniffer" as they kept talking of pinhole leaks in the evaporator coil.

Steve

jeff5may · 08-27-15, 09:19 PM

With a sniffer, you can recover down to atmosphere or less, recharge with nitrogen or argon, and the small fraction of refrigerant can Still be easily detected. Propane will not reach a high psig reading at room temp, it starts to condense. Same with R22.

The flame test will work, though. If you use BBQ gas, you can also smell it when it leaks out, as long as you leave the compressor shut off. If it circulates much, the filter dryer will catch the stink oil, and it will lose its smell. I still like the soap bubble solutions myself. Spray or glop on some Scooby doo juice and watch for foam. Patience helps a lot.

stevehull · 08-27-15, 09:32 PM

Jeff, the unit still has a charge of R22 in it so I don't need to further charge with argon. Or are we talking "past" each other.

Steve

jeff5may · 08-27-15, 09:59 PM

If it is a teeny tiny little leak, a normal charge may not leak enough to detect. If you have a really sensitive sniffer, your luck increases. By stuffing in non-condensible gas, the pressure can be raised so the gas leaks out faster. Once in a while, the seal will fail when the pressure is raised, so having something benign inside is a definite plus. Usually raising the pressure close to the labeled design will reveal the problem.

Also, having non condensing gas in the system will tell you how bad your leak really is. Charge to a target psi, and the gauge pressure will decrease steadily as gas leaks out. With pure Freon inside, the condensed gas will boil off and maintain gauge pressure.

Of course, a good sniffer wand or thick bubble soap solutions will increase your luck. But once you find the source of the leak, then what? The gas has to come out anyway.

AC_Hacker · 08-28-15, 10:22 AM

SH,

Do you actually have the tools to do HVAC work?

Tools like:

Refrigerant Extracting machine
HVAC grade Vacuum pump
Micron gauge
Nitrogen tank
Brazing equipment (& experience)
Manifold gauge set
etc.

You're going to need to assemble (at least) this set of tools to solve your problem.

Also, if you want to keep this beast in the R22 world, you're gonna need a HVAC ticket to get any more R22.

Do you really intend to do all that?

-AC

08-27-15, 08:51 AM	#1
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	GT heat pump - evap coil pinhole leaks I just got a functioning closed loop GT heat pump for $100. But here's the catch . . . Leaking gas from somewhere and the HVAC guys think it is in the evaporator coil. Apparently this particular unit has tiny "bubbles" in the coil that are attacked from the inside (that is what I was told). They suggested some kind of liquid that can be put into the system that "plugs" tiny pinhole leaks. Not a great solution (reminds me of using that crud in car radiators . . . ). The unit is a 2.5 ton, single stage Florida counterflow unit. It was set up for closed loop, so I got the circulation pump as well. A beautiful coaxial coil inside and the scroll compressor works great. I saw it working. The owner got tired of putting in a couple lbs of R22 every six months and the unit is about 15 years old. Ideas on plugging leaks? The alternative is to go with a generic coil as the specific OEM replacement from Florida is almost $1000. TIA. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

08-27-15, 01:55 PM	#3
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Jeff, Water source to air with desuperheater for hot water tank. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

08-27-15, 08:12 PM	#6
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Why not just use an R22 "sniffer" to detect the leak right now? And yes, it has R22 in it right now as I saw it running before it was taken out. I think I can borrow one. Or, I could put in fluorescent dye and look for leaks. I actually helped with the labor of getting this 200+ lb thing out of the closet . . . I need to call as the HVAC guys may have used a "sniffer" as they kept talking of pinhole leaks in the evaporator coil. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

08-27-15, 09:32 PM	#8
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Jeff, the unit still has a charge of R22 in it so I don't need to further charge with argon. Or are we talking "past" each other. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

08-28-15, 10:22 AM	#10
AC_Hacker Supreme EcoRenovator Join Date: Mar 2009 Location: Portland, OR Posts: 4,004 Thanks: 303 Thanked 724 Times in 534 Posts	SH, Do you actually have the tools to do HVAC work? Tools like: Refrigerant Extracting machine HVAC grade Vacuum pump Micron gauge Nitrogen tank Brazing equipment (& experience) Manifold gauge set etc. You're going to need to assemble (at least) this set of tools to solve your problem. Also, if you want to keep this beast in the R22 world, you're gonna need a HVAC ticket to get any more R22. Do you really intend to do all that? -AC __________________ I'm not an HVAC technician. In fact, I'm barely even a hacker...

08-27-15, 11:54 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	What is the unit configuration, water to water, or water to air, or water to line set? Pics would be awesome. If the compressor and/or water pump work, you got your money's worth. Everything else that works is a bonus.

08-27-15, 09:19 PM	#7
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	With a sniffer, you can recover down to atmosphere or less, recharge with nitrogen or argon, and the small fraction of refrigerant can Still be easily detected. Propane will not reach a high psig reading at room temp, it starts to condense. Same with R22. The flame test will work, though. If you use BBQ gas, you can also smell it when it leaks out, as long as you leave the compressor shut off. If it circulates much, the filter dryer will catch the stink oil, and it will lose its smell. I still like the soap bubble solutions myself. Spray or glop on some Scooby doo juice and watch for foam. Patience helps a lot.

08-27-15, 09:59 PM	#9
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	If it is a teeny tiny little leak, a normal charge may not leak enough to detect. If you have a really sensitive sniffer, your luck increases. By stuffing in non-condensible gas, the pressure can be raised so the gas leaks out faster. Once in a while, the seal will fail when the pressure is raised, so having something benign inside is a definite plus. Usually raising the pressure close to the labeled design will reveal the problem. Also, having non condensing gas in the system will tell you how bad your leak really is. Charge to a target psi, and the gauge pressure will decrease steadily as gas leaks out. With pure Freon inside, the condensed gas will boil off and maintain gauge pressure. Of course, a good sniffer wand or thick bubble soap solutions will increase your luck. But once you find the source of the leak, then what? The gas has to come out anyway.