Chimney Staining From Boiler?

[Joe Coastie]

Hi, I'm a new home owner since 2009 and have been plagued for the past year with brownish staining running down my white chimney. I've repainted several times with mansonary paint only to have the staining come back gradualy after rain or snow. The staining appears to be dripping off the corners of the stainless steal cover which leads me to belive that something is being expelled from the boiler which condenses on the cover and drips with the outside mosture.

I've been going back and fourth between my oil company who services our boiler and the chimney tech who cleans our liner, installed the last liner and chimney cap. Oil company says there is nothing wrong with boiler, must be rust or corrosion in the liner or cap. Chimney tech checked everything and said there is nothing wrong with chimney, liner, or cap. I have to agree with the later because as long as the weather is fare, no staining appears and there is no visable rust on anything up there.

I purchased the home directly from the owner of one of the leading home heating oil company's in my area and was told the service tech that the boiler is old but it is a tank and the best the company made (at the time of purchase). And until now has been touble free. I've talked to the owner's son who now runs the company and two of the service techs and they have never seen or heard of this problem before. I'm more than willing to replace the system to fix the problem but my oil company is telling me there is nothing wrong with the one I have.

Please help. I've attached photo's and will list as much info as I can figure out.

Heating System: Last inspected/tested: Oct 2011
Boiler: Burnham V-35
Burner: BKT (?)
Nozzle: size .75; Angle 70*; Spray B
(nozzle was replaced during trouble call for staining, current info follows)
Nozzle: size .85; Angle 80*; Spray A

Combustion Test:
Gross Stk temp: 500*
Net stk temp: 450*
CO2%: 11
Smoke: 0
Breech draft: -04
Overfire Draft: -02

Efficiency Rating: 81 1/2%

[Joe Coastie]

More photos.

[Chuck]

Flue gases are very corrosive, if any part of that meshing or cap is not stainless steel it will rust and the normal condensation will wash that rust down.

Those combustion numbers are ok, flue temp could be a bit higher but is not too bad.

May need to buy a new boiler soon.

[beenthere]

Is the boiler now a cold start boiler.

[qwerty hvac]

It looks like the rust is coming from the bird screen in your pics. Are you sure it is stainless?


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[motoguy128]

I agree. It looks like the very bottom edge of the mesh is rusting. It looks like water can accumulate there. IF hte brown was form the flue gases, all of the mesh and under the cap would be stained brown and the pattern would be less symmetrical.

You may need to remove that cap, replace the mesh with 316 Stainless steel (you cna buy it through Grainger or Mcmaster Carr if you want to DIY) and clean up the surface so that rain drain off properly. The coners should be stainless bars bent at the bottom so it can be bolted down and support that cap. But hte mesh should rest on hte mosonry and be clean, clear and open. No gobs of paint. Any standing water will be acidic and can be hard on the masonry as well.

[heaterman]

Remembering that you are burning a fossil fuel, and as such there will ALWAYS be residual products of combustion, it appears that these products are accumulating on the chimney top. When it rains, the moisture present in conjuction with the heat produced is washing down the accumulation. My only real suggestion outside of cleaning and painting would be replace that particular cover with one designed to fit stainless liner you have now. This staining would not be quite as obvious if you chimney was a tatural brick finish rather than sealed and painted masonry.

[STEVEusaPA]

also, you're barometric damper, and flue pipe are installed incorrectly for oil. Being that someone was up there taking pics, what was the temperature at the top of the chimney?
You sure its a "V35"?

[Joe Coastie]

Wow, thanks for the quick reply. I'll try to hit everyone in my reply.

The cap is SS and gets a very dark chared spot directly above the exhaust pipe. It's my theory that whatever is being ejected in the exhaust is condensing under the SS cap and dripping down with outside rain/snow moisture. The first staining appears just off the chimney corners directly below the corners of the SS cap on the boiler exhaust side. Only later does the staining make its way to the painted bottom portion of the mesh and the corners on the other side of the chimney.

Since these photo's have been taken I have had the chimney recrowned, added 4" to the pipe, and installed a beautiful new roof. Unfortunately the staining continues and is now restaining the newly shingled valley. Everyones first responce has been "rust". Rust in the flange, rust on the mesh, could be rusting rebar in the chimney, and I can't rule that out, but I just don't see it. The staining on the bottom of the mesh(on my sloppy overpainted area) doesn't appear to be rust from the bottom flange. I've inspected that area and can see no corrosion. I think the stain is running down the mesh but can only be seen when it runs on the painted surface.

Just to see what would happen I removed the top SS cover both before the recrowning and after.
Before, during calm dry weather I would see a circular pattern of brown/rust colored specks appear around the pipe. During rain, the crown filled up like a 1/2" swimming pool and staining would run down the chimney.
After, The results where identical with the exception of the standing water which was cured by the recrowning.

I believe the boiler is a cold start. Which if I'm correct means that the boiler pretty much sits dormant until called upon to heat water for heating the home or for general useage.

There seem to be lots of loose debris in the boiler. It's red and crumbles easily. I mixed some with water and prodused a red stain. Not the same as what's on my chimney but maybe if it was diluted it could be?

I would like to be able to rule out or rule in the rust once and for all. Is there any chemical test I can perform on the staining such as litmus paper or some type of solution?

Chuckcrj, you mentioned it might be time for a new boiler, does it look that bad? I have no problem with replacing the boiler but if that didn't cure the staining I'd probably go nuts.

SteveusaPA, how should the barometric damper and flue pipe look? Also, how do I take the temp at the top of the chimney correctly? Don't worry, I won't fall off Beside's its a ranch house and I'm the one taking the pics. Is there a certain thermometer I should use or will the one from my oven work? How far down the pipe should I take the temp? How long after the boiler kicks on do I wait? Also, taking a second look at the boiler number plate it appears to be a V-33 and not a V-35.