Six months after moving into our first home, the furnace had to be replaced. (Because of a cracked heat exchanger that the Home Inspector failed to find - I guess that removing a panel on the furnace was too much work for the guy. Yeah, I'm pretty upset!)

Anyways, the heating company that sold and installed the new furnace said that the new codes required that an intake pipe be installed to feed into the cold air return duct just before the filter. We got a few estimates from other heating companies and none of them mentioned this requirement (though it may have been built into the cost estimate).

The problem I have is that after the installation, the basement temperature now hovers around 37-43 deg F when it is around freezing temps outside. (Needless to say, I am quite scared of freezing pipes!)

The primary reason? Where the round intake pipe (which is roughly 8-10 inches diam) meets with the cold air return duct, there is a square "junction box" of sorts. It is mostly enclosed with sheet metal, but there is a 2 inch strip of wire mesh running around the box where cold, outside air literally blasts out of the mesh in the box.

After calling and complaining, the furnace guy came back out and installed a "flapper" valve which keeps the duct closed except when the furnace is on. This has produced no noticable difference in temperature since the cold air still blasts into the basement when the furnace is on.

What can I do? I have insulated the intake pipe up to the furnace itself, in hopes of reducing the cold radiating from the pipe itself, but the blowing air obviously has much more impact on the temperature.

Why is the cold air return duct not sufficient to feed the furnace? I've half a mind to rip out or block the intake completely and see how the furnace operates just with the cold-air return like the old one did.

Why does there need to be that "mesh" for cold air to vent into the basement?

I am frustrated and I'm hoping someone can offer advice.