I am at a facility which I’m guessing has 75% copper tube and fin (old school) coils and the rest of the 25% newer stuff being microchannel.
We are experiencing a disproportionate amount of microchannel coil leaks compared to traditional coils.
I’m aware of “U-bend leaks... and rubs... but on about 40 coil leaks, these microchannel coils are leaking in the middle, the factory header connections, etc.
A few of our replaced microchannel coils have been leaking again, within weeks to months, probably 4 of them.
Some of these are on chillers, some on AAON systems, some on walk in refrigerators and freezers, some on DX systems, some on VAV systems... the whole gambit.
So, has anyone else had such bad luck with the new coils, or is it just me?
... sitting in the Hollywood Hawaiian Hotel, listening to the air conditioner hum
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Unless its something like a puncture wound on the outside that's easily seen and accessed, most MC coil leaks cannot be repaired. With those, you get some fins out of the way, clean it real good, and solder over with Muggy or Aluxcor or something similar. But almost anything else like a random spot in the middle at the top or if there are leaks at the copper to aluminum transition, is not likely to work.
One I did about 5 years ago, the installers had put a hail guard screw right through the large thick tube that serves as the coil manifold. I thought that would be easy to solder over that hole. It turned out to be pretty difficult to get that huge piece of aluminum hot enough to work with.
The great professors of the art are not immune from the malignancy of matter and the eternal cussedness of inanimate objects.
The question is how are these coils being cleaned? And what's the air quality like?
I've had trouble with some that had old school cleaning solvents used on.
And I've also had trouble with some that were a few blocks from a foundry....
Verify the pumpdown capacity is at least 10% greater than the refrigerant charge. Check your liquid line solenoid location.
Pumpdown capacity varies with the header & channel size. Some units cannot be pumped down and just use a drop out solenoid.
Most of these coils come from China, with a good bit of mfg facility quality difference.
Verify the pumpdown capacity is at least 10% greater than the refrigerant charge. Check your liquid line solenoid location.
Pumpdown capacity varies with the header & channel size. Some units cannot be pumped down and just use a drop out solenoid.
Most of these coils come from China, with a good bit of mfg facility quality difference.
I highly doubt over-charging has anything to do with pin-hole leaks. Have you ever worked on an outdoor refrigeration condenser? They are made to be pumped down, no matter if they have a micro channel coil or not, although I admit they are easy to over charge.
Now to your theory about junk coming from China, you might be on to something. I assumed that most were made in the USA, but now that I think about it, they are something that would be easy to jam into a shipping container and float over here.
Does anyone know if anyone actually manufactures micro-channel coils in the USA, or are they all really coming from China?
If at First You Don't Succeed, Skydiving Is Not for You.
On the larger coils rigging is critical. Little to no Twisting, bending, racking during install.
Smaller coils, 1 - 5 HP I've only seen 1 bad coil on a heatcraft condenser. (Installed by others)
I highly doubt over-charging has anything to do with pin-hole leaks. Have you ever worked on an outdoor refrigeration condenser? They are made to be pumped down, no matter if they have a micro channel coil or not, although I admit they are easy to over charge.
Now to your theory about junk coming from China, you might be on to something. I assumed that most were made in the USA, but now that I think about it, they are something that would be easy to jam into a shipping container and float over here.
Does anyone know if anyone actually manufactures micro-channel coils in the USA, or are they all really coming from China?
Speaking from experience, commercial & chiller, mfg testing, design, warranty assessments, etc; pumpdown can be a major issue. Pin holes were not mentioned in the original post. Warranty Failures were reduced by ~80% when mfg switched Chinese providers.
Mfg mandated coils within x distance of coast had epoxy coatings and recommended for locations with high moisture or corrosive atmosphere.
Coil mounting/ isolation can also cause leaks due to vibration & corrosion.
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Originally Posted by 3.14
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