Combustion Air Problem

Jim Davis_3

Draft reading is a good way to indicate if you have combustion air or not. You can't have draft if you don't have combustion air. The key is what happens to draft after the burner shuts down? Does it disappear instantly or slowly fall? Using O2 readings would be the next ost affective way to determine combustion air problems. If the O2 readings falls continuously during the burner operation this is an indication of lack of combustion air. Unless this is a really air-tight room the odds are against combustin air being your problem.

Harlan_2

Combustion Air Problem

How can I determine if there is a lack of combustion air for my oil furnace. I have a draft gage. The oil furnace sometimes emmits soot out the flue. The furnace is a Thermo Pride OL16-125, 156,250 btu per hr output.

JackFre

\"furnace emits soot from flue\"

You HAVE found out that you have a CA problem. Check out the Tjernlund Inforcer. Operates only when the furnace runs.

Empire_2

You Must

perform a complete combustion test before adding anything. draft guage alone will not do it. Aslo nees smoke test results. Does furnace have a barometric damper? What is the OF draft and the Stack draft? Is the furnace comb. blower clean? There is no easy answer without information.

Mitch_4

SOOT

Soot is either insufficient air, inadequate chimney or draft, or improper combustion set up.

At 156,250 output I'm guessing 1.35 USGPH nozzle @ about 80% eff. resulting is an input of 189,000 (Not familiar with Thermo Pride, so I am using generalities)

At that rate, you need about 10 cu.ft/1000 btu, 50% excess air, and an equal amout for dilution air for the venting. resulting in 30 cu.ft/1000 btu, or about 5700 cubic feet of air available to sustain proper combustion and ventilation. If the room is 8' high this results in a 20 x 35 x 8 foot room.

Do you have it? probably not. Most mechanical rooms I work in are about 1/10 of that. Likely you need to add fresh air, or a means of connecting the mechanical room with the rest of the interior structure.

Is it in a laundry room with a door? when the dryer runs do you have a negative pressure as a result? do they keep the door shut.

Lots to look at. Had a similar situation where the furnace ran fine for 5 years, small mech room no basement. suddenly started sooting. Finally found that the HO installed a new tile floor, and the flooring guys covered the large grated opening that communicated witht he crawl. This was the fresh air inlet to ensure adequate combustion. Breaktile, re-install grate. Problem solved.

So look at if the problem is new,and the furnace is old. What has changed?

Give additional details for mare help on this site. Cant say..its not working, I have soot, what is wrong... details please, room size, input, chimey size, burner settings, combustion analysis.. the more the better.

Mitch

Harlan

I will get details this weekend and post on Monday. Thanks for the help.