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peppie35 03-15-2007 03:05 PM

Furnace & Building Guidelines...
Hey Everyone,

I will be refinishing my basement shortly. The furnace is in the middle of the basement I am assuming for a reason, so I won't even bother moving it. question is whether or not there is a guideline as to how close the walls can be to the furnace. Right now it is in a rather large room and I would like to make it smaller to accomodate more bedrooms and would like to know how close I can close the walls in on the furnace.

Thanks for your advice:)

harleyrider 03-15-2007 03:18 PM

1 inch sides and back.............but in the front i would do a minimum of 3 ft..............leave room for us well fed service techs...........and put a good light and a out let in the room.

peppie35 03-15-2007 03:30 PM

Thanks so much! Because of where the furnace is located there would be at least 5ft in front of no worries It's only the sides that I want to change anyhow :)

Thanks again!

beer_geek 03-15-2007 05:14 PM

I'm guessing they put it there because that was the easiest place.

pjpjpjpj 03-16-2007 06:13 PM

Something seemingly missing above is this: is it a high-efficiency unit with direct-piped combustion air (easiest way to tell.... are there both inlet, and exhaust flue, pipes)? If so, then you only need to have clearances for access and maintenance as the others posted.

But if it is not - meaning it has a big metal flue up and the intake is from the room around it (is there a slotted "grille" look on the burner section?), then you need to make sure you have proper combustion air for the furnace. Local codes usually prevail, but they are often the same as national codes. The size of the opening required will vary with the amount of gas input BTUHs - the code will say something like "x-square inches of opening per y-thousand BTUHs gas input". Many jurisdictions require one opening "near" the floor (typically 1 foot off the floor) and another "near" the ceiling (1 foot down), but some only require one larger opening, anywhere in the room. In indoor applications, these are usually installed just using typical store-bought "return air grilles" that are used to cover an opening through the wall into the furnace closet. Be sure that you are counting "free space" if you use a grille, and not just the "face area" of the grille (typical residential grilles will be "free" 70%-80% of the face area, commercial grilles even less).

Once you have these openings in the furnace room, you also have to be sure that you have enough open area in the adjoining space. If you have a certain room volume per BTUH input (not square footage, but multiply it by ceiling height to give volume), then the space is considered "unconfined" and you do not need air ducted from outside.

I know this sounds complicated, but if you do not check this, you risk the furnace having combustion problems, or at least running very inefficiently. Of course, as I stated above, if you have ducted/piped intake air, then you don't have to worry about all of this.

coolmen 03-17-2007 02:14 PM

Whats the furnace btu (size) ? size of basement sq' , whats the chimny look like ?. most often a louvered door to the mechanical room would work for your combustion air to the room. And is very important for the furnace to work properly .

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