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Oil burner chimney problems-need advice

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Badfish740

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Discussion starter · #1 ·
All the more reason to get cracking on installing central wood heat! Anyway, sitting in the living room I noticed a strong smell of fuel oil and went down to the basement to investigate. Once I turned the lights on I noticed a very fine haze hanging in the air. This is probably only the second time we’ve used the heat this year, and we just bought the house in June. I called the company that had installed the unit and the guy came out and quickly determined that the chimney was not drafting properly. We were able to get it to draft by holding the butterfly at the base closed and running the furnace. At first with the draft open just a bit, hot gases were blowing out forcefully into the basement. Also, when the tech pulled the pipe from the wall there was quite a bit of loose soot in the bottom. Once we forced the butterfly closed the chimney began to draft. However, he recommended we get a chimney company out to take a look. From all outward appearances the chimney looks fine. It’s a masonry chimney (12” x 12” block) with an intact parge coat and cap/screen. I’m going to try to get up on the roof tomorrow to take a closer look at the cap to see if there are any breaks in it where a bird could have gotten inside or something of that nature. I also thought about putting a mirror at the base of the chimney and then shining a flashlight from the top to see if I can find any problems-what should I be looking for? The tech guessed that a tile could have come loose inside and was obstructing airflow-if this is the case would I be looking at relining? How much does something like that usually cost? Would there be any reason I would need an entirely new chimney? If so, is there anything I should keep in mind for the new one given that I would like to install an add-on wood furnace soon?

Thanks!
 
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#2 ·
Well Badfish I can't help much with the chimney if there is a physical problem but maybe I can help with the lighting. If you happen to have sunshine and at the correct angle a mirror will give more light down a chimney than all the flashlights we both own. Good luck.
 
#3 ·
If your house is completely airtight...you will also have problems with draft...for example, you could turn on a vent fan in an airtight house and you will pull outside air in thru your chimney...
 
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#4 ·
You might want to have someone come clean your chimney. They also can tell you if you have a problem with the chimney. You can have it lined it if needed. $1500.00 and up around my area.
While many people use one chimney for a oil and a wood furnace, its better not to. If you have a wood furnace installed they most likly won't hook it up like that.
If you have a clean out door in the chimney you can use a mirror to look up threw anytime druing the day. Like was said, you just need the right angle. Take the cap of will help with light.
 
#5 ·
My uncle found out that a family of racoons would reduce the draft in his fireplace... and keep him awake at night. And on two successive days a blackbird worked it's way past my windproof chimney cap on the woodstove stack and wound up squalking about in the stove. (Talk about a "circus"!:D)

Possibly something got past a broken screen and "expired" in that oil burner chimney but more likely a wasp/bee/hornet nest. Watch yourself at this time of year with any "kleiner buzzenstingers" as they get very feisty with the approach of their seasonal demise! Arm waving and swarm swatting on a roof quickly can become gravitationally painful.
 
#6 ·
I just saw a beekeeper presentation today. They had a glass case full of bees. I wanted to open it so bad...but I probably would have been escorted out.....in handcuffs lol. College is different. :hide:





By the way, no bees escaped. :Disgus:

darn...:banghead3
 
#7 ·
Might also double check that none of the cold air return ducts to the furnace have pulled apart. That could create a vacuum in the basement enough to cause a major chimney back draft anytime the blower is running.


HydroHarold said:
... And on two successive days a blackbird worked it's way past my windproof chimney cap on the woodstove stack and wound up squalking about in the stove. (Talk about a "circus"!:D) ....
Click to expand...
Been there done that about 3 times here. Bad part of not having an air tight stove is all the flopping around in there starts kicking the soot and dust out around the door joints into the room. Still not as bad as the time mom and dad had one come out the gas furnace draft box and fly upstairs into the living room when I was a kid. Birds do seem to have increased intestinal issues when they are panicked. :D
 
#9 ·
Badfish,

Since this is an existing furnace, something has changed. It could very well be the chimney is blocked by a squirrel nest or something like that. The flue pipe will collect some carbon over the years, but usually this won't interfere with the draft. If there is any signs of corrosion on the boiler outside, especially where the copper enters and exits the boiler, this may be signs of leaks that could lead to the failure of the boiler components. Also the leaks can make servicing (cleaning) the boiler not possible and lead to declining performance, including smoke. We just replaced a boiler for this reason last November and it would smoke which would then coat the electric eye and shut the furnace off. When it restarted, the burner was fresh with unburned oil and would smoke when it would light. You may have this condition too. When was the last time the furnace was cleaned and what was the condition? :)
 
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Discussion starter · #10 ·
PaulChristenson said:
If your house is completely airtight...you will also have problems with draft...for example, you could turn on a vent fan in an airtight house and you will pull outside air in thru your chimney...
Click to expand...
Hmmm...this has me thinking. We began the buying process on this house in May and around early June a new roof was put on along with two large roof fans due to a moisture problem in the attic. The fans are each controlled by a thermostat and a humidistat. I notice that even in the cold weather they run quite a bit due to the fact that they are also triggered by high humidity. Could these two fans running be causing a vacuum in the house? The house is nearly 50 years old and I wouldn't call it "airtight" but it's not drafty either. The previous owner also recently installed new windows, so they're reasonably tight. Since the fans were installed over the summer after the previous owner was done using the heat for the year that would explain why we are having problems. Maybe I should try disabling the fans, running the furnace, and seeing if I get the same problem?
 
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#11 ·
First off, inspect and sweep the chimney. A clean chimney will have better draft.

It does sound like you have a negative pressure situation. Often times, people will go around sealing up any draft they can feel. It's easy to feel where air leaks in because of the cold draft but where the air leaks out, it may go unnoticed. Invariably, that ends up starving the house of make-up air as the stack effect lets air out on the upper portions. A proper draft-proofing requires that you seal where the air leaks out, not so much where the air leaks in.

Crack open a window in the basement. If air rushes in with force, you have a negative pressure situation either from stack effect or exhaust fans.

As for the fans in the attic, you need to make sure there is plenty of intake vents. The formula for static vents (no fan) is twice the square footage of intake than exhaust. I don't know how to calculate when fans are involved.
 
#12 ·
I would first check the chimney for blockage and then as others have mentioned for adequate air infiltration for flue draft & combustion air.
The attic fans could be causing a reverse draft and also preventing the boiler from getting sufficient combustion air. If possible, crack open a basement window and see if that helps for a day or 2. You might have to provide a ducted vent from outside to boiler room.
 
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#13 ·
Some chimneys that have poor draft to begin with will react as you have described due to the fact that the flue is cold from not being used for a long period of time,after verification that there is no blockage as others suggest , just let the boiler run to temp and heat up the flue and your draft should improve.If not there are other options to improve draft such as installing a draft inducer tied in with the burner etc., make sure boiler flues are clean also...
 
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#14 ·
Badfish740 said:
Hmmm...this has me thinking. We began the buying process on this house in May and around early June a new roof was put on along with two large roof fans due to a moisture problem in the attic. The fans are each controlled by a thermostat and a humidistat. I notice that even in the cold weather they run quite a bit due to the fact that they are also triggered by high humidity. Could these two fans running be causing a vacuum in the house? The house is nearly 50 years old and I wouldn't call it "airtight" but it's not drafty either. The previous owner also recently installed new windows, so they're reasonably tight. Since the fans were installed over the summer after the previous owner was done using the heat for the year that would explain why we are having problems. Maybe I should try disabling the fans, running the furnace, and seeing if I get the same problem?
Click to expand...
Yes, if you disable the fans and run the furnace and it works that also will show you that you have created a negative pressure situation in your home with the exhaust fans...

Out of curiosity, when you had the new roof put on...did they install a ridge vent system?

And did they install vents in your soffits?

Like LLigetfa said...
Crack open a window in the basement. If air rushes in with force, you have a negative pressure situation either from stack effect or exhaust fans.

And as lt230s said...
You might have to provide a ducted vent from outside to boiler room.
 
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#15 ·
If you have vent fans, you have to also have some fresh-air intake vents or you will create a vacuum. I have small welded wire mesh keeping blackbirds out of my chimney. Couple years ago my furnace would not fire & stay lit. Usually I fire it up ahead of cold weather, but I put it off too late. Turned out that my furnace shut itself down due to pressure building in chimney. It has a pressure switch that shuts it down to prevent backup of carbon monoxide should chimney block off. Well, the blackbirds had actually tore the wire loose from the mortar! Bad thing was the old chimney is crooked in the attic & plain fire brick. Had to use a piece of steel on a rope to try to beat the nest to the bottom. No go...had to drop a burning rag down till I heard it drop down. Had the wife in cellar with furnace to let me know when "fire's in the hole".
I got new wire & reinforced it with fresh mortar & no more problems.
 
#17 ·
Every time we clean a Oil fired furnace we clean the tubes that lead to your chimney out with wire brushes and compressed air..replace the igniter(check the transformer) and (fuel)filter..its a dirty job...if its not burning right chimney means nothing..B,
 
#18 ·
Regarding those attic ventilation fans excessive operation. Some short sighted installers will vent a bathroom into an attic space to save $ or time. Bad idea! It doesn't take too much to run them out a proper vent which saves energy and $ on having the attic fans do the work every so often.... Otherwise it could be a lack of proper ceiling/attic vapor barrier.
 
Discussion starter · #19 ·
Chalk another one up to the collective wisdom of MTF :trink39: It was the combination of no soffit vents and the roof fans which was causing major negative pressure in the house. Fans off = problem solved-chimney is drafting like a dream now. I'm leaving the fans off (there's a cutoff switch which disables both of them completely) is the solution for now. Eventually I'll install vents in the soffits-hopefully I can create enough openings for adequate airflow to the attic with the fans running.
 
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#20 ·
Glad to hear that was the cause. With winter coming on I wouldn't think you would want those fans running anyway, even if there was a moisture problem. They would just help suck the heat out of your house.

Like HH said check the bath fan. I replaced mine last year for a quieter one and when I put it in, the flex duct from the old one wasn't even hooked to the vent terminal on the roof.:banghead3
 
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HydroHarold
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