Insulation around Furnace

I am finishing my basement, and building a utility room with my furnace and water heater. Because of maximizing my space in the usable area, I have a stud wall directly along my furnace(almost touching the furnace). I would like to insulate the utility room, because all of the sound travels straight through the furnace to the rest of the house. I'm hoping that putting the insulation around the utility room will prevent the sound from carrying as much. My question is, can I put fiberglass insulation in my stud walls directly against the furnance? Since the wall is about 1/4 inch away from the furnance, the insulation might rest up against the furnance. Would that be bad? I have both faced and unfaced insulation, and didn't know if one would work or not. I read the vapor barrier instructions, and it did indicate that the vapor barrier should stay away from open flame, but the flame is enclosed within the furnance. Thoughts?

Do you have the specs for the furnace and the clearance need around it, seems to me 1/4 is a tad small, plus what about service on said furnace,Are you planning on drywalling both sides or just one, drywall can be closer then just standard studs. Does this furnace take combustion air from with in this space your enclosing if so you might want to do some checking, I thought I had read that it was 50 square ft per 1000 btu just some thing to check on before you button it all up and cause yourself headaches in the furture.

No, direct contact with HVAC equipment with building insulation is not acceptable. The composition is such with BI that prolonged contact with sheet metal may cause corrosion. Also, the cabinet of the unit may heat excessively in that area causing who knows what kind of failure. In many cases, equipment is designed so that heat loss is a way of keeping the temperatures on the surface low enough. If you stop that air circulation, the heat loss dynamics change. Lastly, faced BI may get hot enough to smolder or char the facing. Can be dangerous.

Unless that furnace is "zero clearance", your walls are already too close it.

Adding insulation to THAT would be referred to more accurately as "adding fuel".

If it IS, in fact a zero clearance model, then, no, it wouldn't be bad, unless it impeded access to important parts of said furnace.

Well I'm glad I posted in this forum before continuing on, as you have asked some interesting questions, especially about the limited space. The furnace I have is an American Standard Freedom 80 Single-Stage. I went to the American Standard website, but couldn't find the specs on whether or not it's a "zero clearance" furnace or not. Just as some more information to provide. I have 2 feet open in front of the furnace, where I was planning on putting bi-fold louvered doors. To the left of the furnace I have 4 feet until the wall. Behind the furnace I have 3 feet of open space, and then to the right I have about 1/4 of an inch of space. The question on taking combustion air from within the space, I am not sure on. I really appreciate your help on this so far. Thanks

Do you have the original paperwork for the furnace?

I only have the User's information Manual, which didn't provide much. The contractor didn't leave me with anything else.

I would suggest calling him up and finding out what the deal is.

You sohuld have possesion of ALL the paperwork that came with that unit, including the Installation manual. You paid for it.

I found the installer's guide, and the BTU rating is 80,000. All air is coming from inside the building, and it indicates that there needs to be 2 permanent openings communicating directly with an additional room with at least 500 square feet. It does point directly to a room of this size. However, I was planning on putting louvered doors in front of the furnace, seperating the utility room and the 500 square foot room. Since they are louvered, would that be considered a permanent opening? I am putting 2 36'' louvered doors, which means in total I have 72 inches of louvered doors. Would that be sufficient?

I prefer that combustion air be piped into the furnace housing, from the outdoors.

If you're talking about two 36" square doors, entirely louvered, equalling 1296 sq' each, sure, it'd be sufficient.

See if you can find the minimum clearances in that book somewhere regarding your original question.

Thanks for the help. You opened my eyes to some things I was not thinking about that could have been damaging to the system. I didn't find anything about minimum clearances for the system in regards to the insulation on whether or not it can be that close to the furnace, so I will contact the company to see if they can provide some assistance on that.

My doors are entirely louvered, and are 36'' square doors. (36'' * 80'' per door). The only part I didn't understand was the "equalling 1296 sq' each"

Unfortunately, the air is not piped in from the outdoors, as it is an existing system, and it would be a little challenging to modify that setup at this point. Good to know though for the future.

Thanks again.

1 sq inch per 4,000 BTUs
100 sq inches min.
2 ducts: top within 12inches of ceiling; bottom within 12 inches of floor
any one single dimension min. 3 inches
If no published data on louvered doors, must use 25% of cross sectional area as available. Metal louvers 75% unless stated by mfr.
Must add up the aggregate BTU inputs. Furnace, DHW heater, dryer, etc.
Can pull from rest of basement only if it combined with CAZ is unconfined based on 50 Cu Ft/1000 BTUs.
Clearances are air spaces. Packing insulation into stated clearances is a major fire hazard. You keep adjacent combustibles warmer while blocking cooling air. Check elsewhere on appliance cabinet for clearances. If not there, contact Mfr with model and serial #. If they say they cannot look up, send Cert. Letter Ret. Rct.
HTH, Doc

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Originally posted by jasonwiest
I found the installer's guide, and the BTU rating is 80,000. All air is coming from inside the building, and it indicates that there needs to be 2 permanent openings communicating directly with an additional room with at least 500 square feet. It does point directly to a room of this size. However, I was planning on putting louvered doors in front of the furnace, seperating the utility room and the 500 square foot room. Since they are louvered, would that be considered a permanent opening? I am putting 2 36'' louvered doors, which means in total I have 72 inches of louvered doors. Would that be sufficient?

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Spend more time reading the book clearance to combustibles should be towards the front of the book.