WE have a 4 yr old home built with Heatilator ND4236. FP exits on westside of home and is exposed to cold easterly winds. We experience severe cold air leakage from base of unit where air would normally be drawn in to be heated. (From what i understand)
Builder did remove siding and make repairs/insulate back of unit during our first winter in home. It seemed to help. During winter of 2008-09 we noticed cold air leaking again and sealed off base air supply, secured gas and quite using unit.
Builder went out of business. Local Heatilator is reluctant to repair as he did not do install. He did suggest removing siding around back of unit, cut out insulation and add bags of vermiculite to seal up outside of Heatilator. He told me, off the record, that Heatilator would advise he to do same.
House is a ranch with vent coming straight out back of unit horizontally Fireplace sits on cement kickout with plywood base. Ground clearance is approx 5 inches off ground.
Appreciate any advise. I was told to figure $2500 to remove and reseal. Also read air leakage is always an issue and most builders were not qualified to do proper install. It is getting confusing!