Gas and Oil Home Heating Furnaces - combustion air required

The oil fire furnace will get enclosed in a "closet". How many square inches of ventilation (passive, ie louvered vents) are needed per btu of furnace?

Thank you

Instead of using a louvered door, I much prefer to bring in outside air directly to the burner. There are combustion air kits available for most oil burners. I've installed many where we bring the combustion air in from either a crawl space or attic. Either of these is actually preferabe to the intake going directly outdoors, in my opinion.

Grady,

thanks for the reply. I know this method is an option. I would like to get an idea how much ventilation would be required and then I can weigh the pros and cons of each method.

Any idea on the square inches / btu requirements?????

Thank you

MINIMUM free area of 2 sq. in./1000 btu input. This is the requirement but I can almost guarantee you will have problems. For my money in a closet installation, a combustion air kit is a no brainer. EVERY furnace I install in a closet gets one. The money you will save by not installing one will very soon be eaten up in service calls.

Check your local mechanical code, there will be a minimum size then everything over that has to be figured if the BTU's are more. Lovered wood slats cut down the free area which is also addressed by the local code, so the slatted area must be enlarged to allow for this.

You probably wanted to hear exact size for your unit, but then, you never provided BTU. You need to know this to figure combustion air.

On your closet, another consideration besides clearances would be the room to service the unit. Just something to consider when you box it in.

I agree with Grady..

You're best to go with the kit..

Pro of the kit?

-Your burner is getting fresh air at all times from the outside.
-Cuts down on drafty windows/fireplace/doors.
-flame may burn cleaner.
-Do not need the "eyesore" grills on closetdoor..
-Sound is sealed behind the door since you don't need the grill for fresh air on the door.

Con
-Depending on the layout, may be harder to get to the outside wall
-May be a higher upfront expense


Pro for the door grill
-Cheap
-Easy


Con
-Air is drawn out of the house, so the lost air is coming in your windows/doors, and other leaking area from the outside.
-Open grill in door maybe noisey
-Burner may not burn clean since who knows what maybe in the air.