SHOP FURNACE HELP

[WAYNE0]

I finally got my small addition built to get my oil furnace & compressor out of the work area. It is 6ft x 8ft I do all my body work & paint in a 16 x 30 garage. With the furnace in such a small area can i pull air from outside ? I was told i had to put duct work from the furnace to the inside of the garage its self to get air for the furnace. The issue with that is when i run my exhaust fan when im painting. The exhaust fan will take air from the furnace. I had that problem when the furnace was in the garage.

 

[Dana67Dart]

On a forced air nat gas furnace, the air for the burner combustion comes from the ambient around the unit itself.

On a direct vent system the combustion air comes in from outside and exhausts outside

It sounds to me like you have moved your oil fired furnace to a shed outside of your garage.

The combustion air should come from the ambient air around the unit in the shed, or a dedicated intake to the unit if it is a sealed combustion type.

Then a Separate supply and return of heated air from the unit to the garage and from the garage back to the unit, would separate the combustion gasses from the garage space.

How about a photo of your oil fired furnace

 

[67Dart273]

The whole deal is, an exhaust fan (WHICH SHOULD have "makeup air" from the outside)---will cause a vacuum in that space. Your burner is combustion air into the combustion chamber through the burner---up through the stack and draft regulator--to the chimney device. You are pulling a VACUUM on that burner inlet, which in "worst conditions" can actually suck BACKWARDS down the chimney and out the burner!!!

YOU MUST have the furnace in an area SEALED OFF from the garage.

YOU MUST have ductwork SEALED to the furnace to provide RETURN air from the heated space, and HEATED supply air to the heated space.

This leaves COMBUSTION air to the burner, which now should be SEALED and SEPARATE from the garage work area.

Now you MUST deal with the confined space in which the furnace is installed. You can find charts that relate furnace burner BTU to square inch area of combustion air vents. These vents, if screened must be made larger

because of the screening. This is because in a "static" (non forced air) vent, the screen can reduce the effective vent area by as much as 50%. You want a vent up high on the all, and a vent down low. I do not remember, anymore, what the minimum figure is. Also, in a hazardous area, you want any source of ignition 18" or more off the floor

 

[67Dart273]

EXHAUST FAN makeup air: Regardless of your furnace condition, in the winter you would be pulling OUTSIDE air into the building (and should at least have a door/ damper/ window for that purpose). Larger / better shops would have a DUCT FURNACE, in other words a furnace right in ductwork, to heat the incoming cold air and discharge that right into the shop.

MANY makeup duct heaters are DIRECT FIRED which means the "fire" (gas/ LP/ whatever) is "right in the duct." HOW does this not poison you? AIR DILUTION. A duct heater pulls in WAY more air than the burner uses, so the CO2/ other burner combustion products are mixed into the incoming makeup air such that "it does not hurt you."

 

[WAYNE0]

What i ended up doing is taking a clean 55 gal. drum & using it as my oil tank for now. I put it out side right beside the furnace and higher. Also i replaced the nozzle. The nozzle was new from last year but that did the trick. It runs good now. I made sure the nozzle was the same. The only difference is the GPH The nozzle i took out had 100 GPH on it & i couldnt find one so i got one that has 70 GPH on it. Thats the highest one i could find. Not sure if that will make any difference. It seams to be running fine.

 

[WAYNE0]

yes sir

 

[67Dart273]

It would not be 70 per hour. Think about that. Your 55 gal drum will be gone in less than an hour. More like .7/hour

If you can, you should consider no1 for an outdoor tank. Is the burner double lines? Suction plus return? That would help some with an OD tank to keep things flowing.