Thread: Scorch at oil furnace

Can anyone explain what would cause this condition?

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Originally Posted by Jon mackay

Can anyone explain what would cause this condition?

That would be backdrafting, I think.
Do you have a picture of the vent pipe? If it does not have a barometric damper installed, that could be the cause. The damper may have been stuck at one time.
If there's a chimney cap, it may catch wind from a certain direction and cause that. It is not uncommon to see that on an older oil furnace.
I call for the nozzle to be changed every two years. There should be a record of the last time it was serviced.

Here is the vent, the damper was free of blockage. The unit is only 12 years old but I'm thinking it has not had any maintenance.

Oil burns dirty and clogs up the show. If you open the port at start up and get a blast of exhaust gas coming out at you, it means the unit is plugged. Needs to be serviced.
It could also be just poor draft, high wind storms, lots of things. Typically though the hand test over the port will tell you how it's drafting, or you could buy a kit like service techs use.
Then you would have to use it though.

It doesn't look like there's adequate clearance from the studs at the smoke pipe.

The beckett burner usually has a 80 degree nozzle and it builds up carbon around the difuser. If the sight door is not secured closed, the unit will blow back on start. Looking at the stack damper it doesn't lok like a draft problem. Shut the switch and take a lok inside the sight door. Sometimes the metal chamber gets burnt up and the unit will need to be replaced.
Hope this helps

I did see some dark staining above a couple of the registers. Could there have been a puff back?

These burners should be cleaned and set up yearly. The scorching you are seeing is from a positive pressure in the firebox hopefully only at startup,it should have an overfire draft once it has run for a minute or so. Proper draft in the flue should be checked as well as the correct nozzle size and spray pattern.

By the way, there is no fire valve on the oil line at the burner, the flue pipe is not up to code, and I did not see a service switch or thermal safety anywhere.

At which registers did you see the darkening? Were they in the same room or different parts of the home. You may have a damage pelum in the chamber area if they are in different registers

I'm quick to call for service on gas furances... even quicker on oil. Oil is a very dirty fuel compared to natural gas and propane. My diesel truck fuel filter needs to be changed every 10K miles if that's any indication (same fuel as an oil furnace). On oil furnaces nozzles get clogged and filters get plugged quickly.

I'm not sure if these things have anything to do with the picture. I don't spend much energy problem solving furnaces... leave it up to the pros.

Originally Posted by Dave Wheeler

At which registers did you see the darkening? Were they in the same room or different parts of the home. You may have a damage pelum in the chamber area if they are in different registers

The staining was at 2 separate bedrooms but I didn't see anything anywhere else. see pics.

Lack of filter changes maybe, but from what little I saw of the ductwork it was sealed with silver tape. I can only expect to see the same on the return leaving the opportunity for unwanted air from the basement being introduced to the system. This could include backdrafted air from the heating system or water heater. along with any associated by-products of basement useage.

The chimney connector is undersized, unsupported, taped joints, and inadequate clearance to combustibles. Technically, it would need a listed pass-through to penetrate that combustible wall. Is that a gas WH common vented into it? If so, what does the top of the WH look like at the draft hood or at the TPR valve? Burner compartment?

David covered a lot of good points. Oil definitely needs annual service including changing nozzle, filter, strainer, gasket, clean & inspect electrodes, test function, test cad cell, check pump pressure, check fuel vacuum, and full combustion analysis once unit is cleaned up.

I can't make out which Honeywell primary you have but if it doesn't have a pre-purge and post-purge, I'd recommend it. That will minimize that mini puffback you get on initial firing and cut down condensation.

Yes, a lot we can't see where. I would be esp. concerned about ducts sealed with the BPM all over the house. BTW, the homeowner insurance should be called to clean this up. What you see on these walls is the tip of the iceberg. Could have a field day with this installation.

What kind of chimney? I didn't see a cleanout but it appears to be a factory chimney. Any pics of vent termination? Inspect the flue?

Never enough pics....

Originally Posted by Jon mackay

The staining was at 2 separate bedrooms but I didn't see anything anywhere else. see pics.

are those bedrooms above the furnace? I would recommend performing a "smoke test" in order to check the condition of the pelum. they put a smoke bomb in the furnace and run the fan only to see if you see smoke or you can use a carbon monoxide test and see what readings you get when the furnace is on.

Originally Posted by Bob Harper

What kind of chimney? I didn't see a cleanout but it appears to be a factory chimney. Any pics of vent termination? Inspect the flue?

Never enough pics....

Here is the chimney, thread of its own..http://www.inspectionnews.net/home_i...mney-type.html

a draft test should be taken. You may need a larger squirrel cage on the top of the chimney

Well, that explains a lot. That unit needs a decent set of lungs first. FYI, you cannot install unlisted terminations onto factory chimneys.
You may not be seeing BPM all over the house but its there-trust me.

Damaged heat exchanger.

Originally Posted by Raymond Wand

Damaged heat exchanger.

Tough call if you can't back it up.

Tough call? I guess its like all the other guesses above. Besides I wouldn't leave it at that, I would be putting in my report to have the furnace serviced by technician prior to close of title.

I have to agree with Raymond. Put it in your report to have it checked out by a pro.

Originally Posted by Bob Harper

Well, that explains a lot. That unit needs a decent set of lungs first. FYI, you cannot install unlisted terminations onto factory chimneys.
You may not be seeing BPM all over the house but its there-trust me.

Bob Harper,

Chalk it up to a senior moment...after too much time with the cardiologist recently, having a brain f*rt on the TLAs (Three Letter Acronym/s) tonight...BPMs? all over the place?

BPM - brushless permanent magnet motors? all over the place??

Beats Per Minute??

Burnt Particle Media?

Lost on the TLA.

Batch Processing Monitor - What does BPM stand for? Acronyms and abbreviations by the Free Online Dictionary.

LOL HG!

Black Particulate Matter--It's an acronym I've used here many times in lieu of "soot" because, once it's outside the combustion chamber, you cannot assume it is indeed, soot. I have worked for years on cases where a house is "sooted up" only to find out the black stuff or BPM turned out to be other particulates such as dirt, mold, metal filings, skin cells, etc.

There are many labs who will tell you a sample is soot based upon improper tests to make this determination. The lab I use begins with Polarized Light Microscopy or PLM to determine morphology. You can usually distinguish hydrocarbon soot from other particulates simply by PLM and referencing known traits about various particulates. For instance, soot from short chained apliphatic hydrocarbons such as NG or LPG is a light, friable, crumbly matrix that crushes into dust on a slide using a micro tool and disperses. Soot from long chain aliphatic hydrocarbons such as diesel fuel, heating oil, cooking oil, candles and scented oils appear as a greasy non-dispersing matrix and often has yellow specks in it. Then, if you really need to determine exactly what the particulate is, you run Gas Chromatography with Mass Spectrometry (GC/MS) to identify the actual compounds in the matrix. You could use Scanning Electron Microscopy (SEM) but that would simply give you an elemental analysis and not prove just where the particulate came from.

Then, the researcher must have a knowledge of buildings and systems to inspect the home and determine the mechanism for distribution of the particulates and why it deposited where it did. Insurance companies are finding it cheaper to pay me to do this investigation and get to the root source then prescribe measures to prevent its reoccurence.

Class over. HTH,
Bob

B.H.,

LOL back at you! I knew I had seen your TLA: "BPM" before - just couldn't get over the brain strain after having it used regards "the ticker" so frequently in the recent past.

Thanks for the clarification. At least I got the "particle"/particulate part almost right

Have a great week.