My basement presently gets heat from one register and from the heat radiated by the furnace itself.
When the 80% runs it seems like it keeps the utility room toasty. If I get a 90%, with an enclosed combustion chamber, and a well insulated furnace cabinet, then won't it be radiating less heat into the utility room ?
To me it seems like the draft inducer on an 80% is basically an air pump that sucks air from the basement and exhausts it through the chimney. The air that is being sucked into the basement can be coming from anywhere air can infiltrate into the basement which includes cold outside air.
But with a 90% it seems like their is no such vacuum in the basement. The inducer is getting it's air from a special air intake pipe to the outside.
So would it be correct to conclude that a 90% will reduce the amount of outside air being infiltrated into the basement ? All things being equal then it seem like a 90% would cause the basement to be warmer since less cold outside air is being sucked into the basement.
I'm probably overanalyzing all this. Practically speaking does any of this matter ? If the radiated heat from the furnace is much less with a 90% then maybe another heat register need to be added ?
Call a local contractor out and see what there thoughts are.
If it were me I'd find a way to run a duct into the utility room so you are heating it the right way.
air takes the path of least resistance, therefore, your combustion air may be coming down the basement stairway and leaking in around you old leaky windows(?)
a 90% will use outside air for combustion creating a more positive air pressure inside the home. the furnace and ductwok will still convect some heat to the basement, but in all reality, you have probably been heating your basement from the combustion air draft down the stairway, or from the leakiest point in your home.(fireplace?)
Billva is right on the money! Combustion air has to come from somewhere. With the 90% furnace it will be directly from the dedicated pipe. That's why direct vents are the most desirable. They do not create a vacume inside your home. A lot of people don't realize this. Especially if you have a wood stove. They need tremendous amounts of oxygen to burn properly. When I had a woodstove I always had a window cracked open near the stove. When I replaced the woodstove with a free standing gas stove I put in a direct vent.
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