We have a Heil heat-pump outdoor unit (the air handler, ducts, etc. are in the attic) that has been leaking since we moved in back in 2003. We've had 5 different HVAC techs come out to recharge/refill the freon and search for the leak(every summer) - but no luck. They use a sensor that's supposed to beep when a leak is found but - again - no luck. We've been refilling now for four years! The old unit on the other side of the house works fine(it's 16 years old). Any suggestions?

Thanks so much for the advice! The stop leak has been in the system for some time now. How does one get it out of the system? Also, how can I independently confirm that freon is indeed leaking? Couldn't a tech just tell me HP is leaking, even if it's not? If it is leaking, it's doing so very slowly because the house is still comfortable; it's just not as ice cold as it was when the stop leak was first applied and freon added. Is it normal for the HP to overcool immediately after freeon is added and then shift into a comfortable range several weeks out? Should I wait and see if the house gets noticably warmer, thus proving there is a leak (and not having to rely on a tech's say-so that there's a leak)? If I wait, am I running the risk of further damaging the system? Lots of questions I know, but I appreciate the advice.

Hi akrauss....Yes, R-422 is officially Dupont's R-422b and it has a capacity loss of about 15% over R-22. Heat Siphon is likely telling you R-422 is higher efficiency because they do not have any 410a product to offer yet and can offer a "green" solution by simply changing the refrigerant in their R-22 systems to R-422 as both are compatible with mineral oil that is used in R-22 compresors. My guess is heat siphon will have 410a a year from now due to the higher R-422 expense when compared to R-410a. This gap in refrigerant price will only widen as R-410a production ramps up and R-422 production dies a natural death due to low demand. Related to #3, R-410a is a genuine Dupont refrigerant that is not a drop in for anything. It is a stand alone refrigerant that was designed from the ground up as a "green" refrigerant in the early 90's that does not contain hydrofluorocarbons. R-410a can not be dropped into an existing R-22 unit, because it runs at considerably higher pressures that would damage the R-22 compressor and other components in the system. Also R-410a is not compatible with mineral oil that is used in R-22 compressors. The R-410a compressors are charged with POE oil which is compatible with R-410a and are designed for the higher pressures. R-410a is a more efficient refrigerant than R-22 due to it's lower viscosity and therefore lower pressure drops in the system. I do not doubt that Heat Siphon is selling R-422 units overseas. This is because Europe mandated "green" refrigerants years ago and the only way Heat Siphon could sell product to them is to use a green refrigerant such as R-422 or another refrigerant that is used widely in Europe which is R-407c. R-407c requires POE oil just like R-410a so R-407c systems require special compressors that are priced accordingly. Heat Siphon is using R-422 because it is a direct drop-in and they can still use the R-22 compresors and other components as-is, all they have to do is change refrigerant if the unit is destined for Europe. Unfortunately, these Europe units are not as efficient if they have R-422 due to the capacity drop I mentioned earlier. In the pool industry though, I find that there are no efficiency standards and there are lots of false marketing claims out there...mostly heat pumps and pool pumps from what I'm learning from being an HVAC guy who is also a pool enthusiast. Sorry for the long winded message, but I think you were asking for this level of detail. Lastly, I would definitely chose R-410a over R-22 or R-422 units. It will offer the best life cycle cost. Both R-22 and R-422 will be expensive in the near future as the life of both refrigerants is limited. R-410a's life has just begun and will likely not be short-lived. Hope this helps!

The noise might be coming from metalic objects touching and vibrating or fan,wouldn't venture an estimate without having hands on. This I'm certain of,that black splatter is not oil from inside compressor if the compressor still move's refrigerant . What in the world is the black stuff resembling tar paper or plastic sheet? I've seen hundereds of Trane units and none had that. Seems like it would block air flow.