I live in Michigan, and recently had a fresh air intake put in that routes to my return duct on my furnace. It was professionally done, and put in to code. "First 10' Insulated." However, the remaining 12 feet, when the outside temperature drops below 20 starts to get condenstation, then below 15-10 range, freezes rock hard.
I had them put in a shot off damper, and it has a one way valve in the line. My question is, why is it freezing? Is my house constantly pulling in cold air, and if so, why?
What do I do to fix the problem. The general health of my family, since we put this in has greatly improved.
Your help would be greatly appreciated.