I have a house that is about a year old now and this is our first winter in the house. We have a Direct Vent fireplace which is installed in a cavity that extents out of the main part of the house. It is well insulated and there seems to be some (not a lot) cold air comming into the space. I have taken the mantle apart to see if there is any air leaks in the system and doesn't seem to be. I did notice that when i had it apart it was not a cold becuase there was warm air from the house going into the space. I was wondering if it would be ok to take and put a run from my furnance (which as enough capacity) into that space to add a little heat to the backside of the fireplace.