Hey guys, I have a major issue in being able to get makeup air in for the updraft furnace (non-HE).
As it stands the furnace is from '89, but with the heating bills so low, and the condition of the furnace (basically new internally) because of the low run-time (max 5-6 hours a day in -20 degree weather to keep the place at 70 degrees) I have no interest in replacing it. It is a 78% efficient 100k BTU Carrier unit from that timeframe and works great. I am also running a Heil 3-ton central air unit (I forget the age on that, I think it is from 2002-2004 if i am not mistaken and a 10-SEER unit). The AC unit seems undersized for the house, but once the house is at temp it runs about 75-80% of the time to keep things cool even with 105-degree heat outside.
Now, the house is extremely well insulated (8" thick walls, fully insulated, 1" drywall inside with 1/4" plaster on top of it and 3" of red brick outside for a total wall thickness of 11", and the foundation is double-wall thickness as well) and energy efficient, this place is basically sealed tight once the fireplace damper is closed and all the windows are closed. We heat/cool the entire space (including the theater and rec-room downstairs as well as the extra kitchen and utility side of the basement)and are very happy with the energy bills for the space we have. We are heating/cooling approx 4800 sq/ft of space total.
The issue I have is the way most of everything is finished downstairs I have virtually no place to go out the back of the house to plumb in for make-up air for the furnace.
Since I installed the Radon abatement with a sub-slab depressurization system as well as taping up the two vents in the utility side with foil duct tape, I noticed over winter that a couple times I have had the heat-vent safety switch trigger because hot air was not being pulled up the chimney flue because of a downdraft condition where makeup air was being pulled through the chimney.
At this point I am left with very few options to be able to get makeup air into the utility area. Due to the construction on this place I do not know if it is feasible to get makeup air from above the house (no idea how viable it would be to go through the walls down to the utility area) and putting vents out eh back of the house is damn near impossible unless I go out the basement into the garage and out the back of the garage. My issue there is everything here is finished walls (and I mean plaster over drywall and insulated to the hilt) and i really do not want to lose space in the garage due to piping.
Outside of the makeup air issue I am also looking toward the future and if I ever have to replace the furnace I would probably have to go with a dual-PVC install like more HE systems have and the only thing i could find that looked even viable would be one of those tube in a tube systems that vent above the roof and put the makeup air pipe inside the exhaust pipe. Personally I think that I would prefer to put a system like that up the existing chimney flue instead at that time, but still am concerned because I have a decorative chimney pot at the top and wouldn't want something jutting out above it, so that may be fine for the exhaust, but I still have an issue with getting makeup air in.
Any and all suggestions would be appreciated. I would rather deal with this now before fall gets here. I already know about the nice makeup air vents and how they work, just that I am having a hard time coming up with a way to get air in that wouldn't cause a major eye-sore on the exterior of the home.