Dear Richard… my partner and I moved into a brand new mill conversion/rehab condo last year that we absolutely love, but after the summer was over, I went into the utility closet (where the air handler/gas furnace are) and noticed that there was copper corrosion crust/rust that had run down from the air handler (not sure from where, but somewhere fairly high up on the AHU). It had dried up, and didn’t seem to be enough to run down the sides of the burner even–no streaks). This winter, though, I noticed that the suction line has a 1/4 inch gap below it (crappy install?), and that warm air was blowing out of it! There is a rubber gasket around it but still an open space around the copper pipe. I’m assuming that in the summer, cold air comes out of the same hole, and condensation must form on the first uninsulated 1/2 inch or so of the suction line, then run down leaving dried up copper oxide on the burner. It’s also rusting the bolts on top of the burner. Plausible? How do I deal with the AHU? A little expanding foam? It would have to be replaced every time the panel comes off, though. Should this air be allowed to escape? It seems like a lot of air coming out. Thanks SO much, I have learned a lot from reading your articles! Also, what is a typical donation amount to your website?
Leaking Air from the Air Handler Answer
Great to hear there are readers out there who appreciate my articles……..I know they exist but i don’t get many emails like this. It is also a good thing that you take the time to look at the equipment from time to time. It never hurts just to take a cursory look at your heating and air conditioning equipment from time to time. To answer your question, any air leaking from the air handler should be sealed. The air leak you describe is common. The suction line and liquid line which run from the condenser to the evaporator (inside the air handler) penetrate the cabinet and usually on most brands have a rubber gasket to prevent such leaks as you describe hear. Many times though the gasket dry rots or doesn’t make a good seal for one reason or the other. The air leaking from this place where the suction line and liquid line penetrate the air handler cabinet is minimal but it is expending unnecessary energy and conditioning a space that usually requires a) no conditioning at all or b) already has conditioning supplied by design and not because of an air leak from the air handler. Seal up that hole with some good duct tape or the expanding foam will work to but be careful not to get too much inside the air handler lest you get some on the coil and cause a blockage in the evaporator coils which is worse than your existing problem.
Suction Line Insulation
The suction line is one of the pipes which penetrates the air handler cabinet. It is the larger of the two pipes which penetrates the air handler cabinet and it carries vapor refrigerant back to the condenser. This refrigerant vapor is cold and usually below the dew point. From reading some of the articles on this site you should know that anything that is below the dew point will sweat the moisture out of the air and this will cause moisture problems. Insulate that line and make sure it is sealed good to prevent moisture from forming on the pipe under the insulation. This is called creating a vapor barrier to prevent humidity in the air coming into contact with the pipe. You can get pipe insulation (usually called rubatex and its black) at your local hardware store in the plumbing section. Insulate that suction line to prevent moisture problems including rusting of the equipment. Good luck and keep an occasional eye on your HVAC equipment.