I have a Carrier 58 MVP furnace (100,000 BTU) and a 2-speed Carrier AC with cased A-coil. I also have the 20" EZ Flex filter underneath it, above the under-slab returns. I've been getting an odd/faint burning/slightly musty odor with furnace operation with this new system. The new system was installed in June 2004 and they've replaced the blower motor that locked up, inducer fan motor that died, pressure switches, and main board, and I'm on my third thermostat due to the dehumidify function not working. The furnace has been a lemon. The blower and its compartment and coil and its case show no signs of anything besides a little dust from my EZ Flex filter blow-by issue.

In summer of '03, the foundation was dug completely, foundation waterproofed, and drain tile was installed. I left the old HVAC system in place for nine months after that without replacing system to make sure ducts did not re-flood or give off odor before purchasing a new system. They did not and I had no trace of any odor or water, even after heavy rains. I actually had no odor at all until the original inducer fan casing in the MVP furnace allowed water into my new furnace during rains back in late July '04, due to 2" of sealer missing from the factory on the inducer fan casing. It was water that came down the PVC pipe from the roof when it rained. After repair and filter replacement, that damp odor was gone. It wasn't until the furnace was later used in late September that this new odor popped up. I think this odor is a furnace problem. Check out my thread under residential for all my furnace troubles. Dealer claims it's my ductwork under the slab, yet there is not a trace of water and I had no odor with the previous system and none with the new AC(only furnace) except for the previously mentioned inducer casing issue.

I'm not impressed with my EZ-Flex filter. They used the assembled-on-site cabinet that came with the furnace and the filter fit is not tight and I'm getting blow-by. I want to try a 1" carbon filter in the blower compartment above to test the dealer's theory.

-Could any of you recommend a specific carbon filter and point out any negatives to using them, if there are any?

-Can the carbon filter be used in conjunction with the EZ Flex or will there be too much pressure drop?

-What can I do with the cabinet of the EZ Flex to fix the blow-by issue? Foam tape on the sides, etc.?