From the very first day my new Lennox HVAC was installed at the beginning of 2009 there has always been a musty order coming out of the vents when the heat is on. The installers said it would go away, but it hasn't. Its a very strong smell and does eventually go away with constant use of the heater, however if I stop using the heater for a day and then turn it back on the smell comes back just as strong. I called the installer out to fix it just last month, but of course by the time they arrived the smell had gone becuase I was using the heater constantly.
When the HVAC was installed they did not replace any of the duct work or the plenum. Is the plenum the problem?
I suspect the musty smell must have something to do with water build up or condensation. Thoughts?
I've also pour bleach down the drainage tube each month to kill any mold build-up but this has no affect on the musty smell.
ALSO, the installer tried to save me money and let me in on the secrect of using mastic to sesl the plenum and all duct work joints. I'm starting to think its the mastic that is causing the issue. Thoughts?
My system is as follows:
Lennox G60UVH(X) Series Gas Furnace
Lennox Elite Series XC14 Air Conditioner
Ultra Violet light installed between the A-frame coils that is always on.