# Building walls around a furnace



## amazinlittledevil (Jan 4, 2007)

I am finishing off a basement and want to enclose my furnace in a room with a door. Does anyone know how far from the furnace the wall should be?


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## #CARRIERMAN (Oct 18, 2006)

Hi amazinlittledevil

If you can find the owners manual to your furnace, inside the manual will be the clearance guidlines. My preference as a servicer, is enough room to comfortably service the equipment or change it out. But I believe the standard rule is 3" back and sides 18" front and 24"top. But like I said, check your manual first, this may not apply to all furnaces.

Good luck 
Rusty


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## amazinlittledevil (Jan 4, 2007)

Thanks I'll try that.


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## redline (Mar 5, 2006)

Depending on the type of furnace you may have to allow for air to enter this enclosure.


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## concretemasonry (Oct 10, 2006)

If you have a fresh air intake into the area around your furnace, you may be required to insure that the fresh air (usually cold) gets to the furnace and is not spread into the rest of the basement.

This helps with energy, CO and venting.


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## amazinlittledevil (Jan 4, 2007)

I do know it has a fresh air intake from outside going directly into the funace, its a white PVC pipe that reads "intake". There is also ont that reads "outlet". I'm assuming this is the fresh air for the combustion. The funrace also pulls return air from many return vents in the house. I do now that Im going to have to provide some fresh air for the gas water heater that is in the same room right next to the furnace. Im just not sure how to do that?


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## trollmastergeneral (Dec 19, 2006)

What you should do is get two 4 inch fresh air vents.Then you can get 4 inch insulated flex to run into your mechanical room.One vent you will want up high the other you will want by the floor.:thumbsup:


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## amazinlittledevil (Jan 4, 2007)

Trollmastergeneral,
Once I box in this mechanical room I will have a large open space in the basement. Should the vents pull air from that space _*into*_ the mechanical room or from outside?


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## trollmastergeneral (Dec 19, 2006)

codes usualy require you to pull the fresh air from outside.The reason for this is so the air that is taken from the house and sent up the chimney is replaced so there isnt a negetive presure in the building


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## #CARRIERMAN (Oct 18, 2006)

Hi amazinlittledevil

All the points that these guys brought up are extremly valid. You have one advantage that would make your inclosure alot easier. Apparently the furnace you have is a 90 plus furnace and does not require another source for combustion air. This will save you a ton of trouble. But without adding the combustion air into the closet you ar limited to this style of furnace, but with fuel costs skyrocketing, thats not a bad thing.

Good luck
Rusty


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## concretemasonry (Oct 10, 2006)

amaxinlittledevil -

Keep in mind the difference between "vents" and cold air returns.

Vents supply air for combustion.

Cold air returns allow the cold air in a room get back to the furnace to get reheated and recirculated. If you do not have returns in your basement, it can be hard to heat and the air will be stale.

The two (vents and returns) are separate and should not be confused.


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## trollmastergeneral (Dec 19, 2006)

I beleive there is a water heater that still needs make up air


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## amazinlittledevil (Jan 4, 2007)

The furnace has both supply air for combustion and return air vents. The return air vents are located in the upstairs as well as the basement. The fresh outdoor air for combustion goes directly into the furnace with a white pvc pipe. I now that the furnace has everything it needs to operate in an enclosed space. Im just not sure what i need to do to provide to the water heater once I close in this area with walls. Will this small room need frehs outside air or can I simply draw air in from the the rest of the basement via some vents in the walls that I build around the furnace and water heater.

Its the water heater I need to know about.


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## #CARRIERMAN (Oct 18, 2006)

Hi amazinlittledevil

You will want to bring fresh air into it for the water heater from outside the house. Sorry, I about mislead you there. Trollmaster was on the money with his response.

Rusty


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## amazinlittledevil (Jan 4, 2007)

Thanks everyone for the good advice.


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## MLO (Jan 7, 2006)

Can supply air come from a vented crawl space or even a vented attic, or does it have to come from outside the building?

I am wanting to do a very similiar type enclosure and was going to install ducting in the stud cavaties of the new furnace room with one venting from the crawl space into the furnace room (floor level) and one going from high in the furnace room to the vented attic. 

Sorry for the interuption...


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## #CARRIERMAN (Oct 18, 2006)

Hi MLO

It is actually best to bring it in from both if you have that option. This gives you the required high / low combustion air. The only thing you are not supposed to do is draw it from the living space. However as I have found out on this sight, it is apparently legal in some parts of the country to draw off the living space. Make sure to check your local mechanical codes to be sure.

Good luck
Rusty


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## KUIPORNG (Jan 11, 2006)

Don't see that upstairs, but may be you can use those special door for the furnance room which has a lot of slots in it for air flow then you don't need to open up vent for the wall...


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## pjpjpjpj (Aug 31, 2006)

If the adjacent "open" space is large enough (based on room volume), many codes consider it "unconfined" space, and you can use this for combustion air for the water heater (or any gas appliance), rather than having to duct from the outdoors. It is a simple calculation if you check your local code, although often the adjacent space is not large enough (code people couldn't make it THAT easy on us, could they? :no: )

Usually, you will first have to compare the adjacent space volume to the BTUH input (gas) of the appliance, which should be on the appliance label. For every 'X' Btuhs, you will need 'Y' cubic feet of space in the adjacent area in order to consider it “unconfined” ('X' and 'Y' vary per local code). And then if you determine that the adjacent area is considered “unconfined”, then you will also have a minimum free area of vent (a wall grille, louver, hole, whatever) that you have to provide between the room with the appliance and the “unconfined” room. Many times (as some mentioned here), codes require a grille (or louver, hole, etc.) near the floor AND near the ceiling.

Check your local mechanical code – it is usually pretty straightforward.


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## nicedeals.co.uk (Jul 31, 2007)

amazinlittledevil said:


> Thanks everyone for the good advice.


How did you get on with the installation? I'm about to do a similar thing and found this thread. Good advice guys. Thanks!:thumbup:


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