Buderus startup rumble/soot -- caused by leak or something else?

ineffable

My <2 year old Buderus g115/ws3 with Beckett AFG hard locked out so I had it serviced.

The tech found that the boiler and vent pipe filled to the top with soot. He cleaned everything, changed the nozzle (.65 45b), oil filter, and pump strainer. He found the igniter was not working so right so he replaced it and also increased the pump pressure. The tech reports he got the burner running correctly, but the draft was inadequate and the boiler could not run without sooting . He suspected chimney blockage. However, chimney sweeps, whom I subsequently called, found no blockage. The tech did observe that the boiler leaks water between the sections into the combustion chamber when cold.

On startup the burner starts with a low tone for about 5 seconds, wobbles for a couple seconds more, and then shifts to a stable burning sound. Black, sooty smoke is visible coming out of the top of the chimney, and the boiler interior is caked with soot.

It is unclear what has changed since last year -- prior to it sooting up it seemed to run fine, no weird noises, no odors, no loss of flame. None of the equipment was replaced, and the boiler room, chimney (interior), and oil tank (indoor, in good shape) are the same. The tech is completely mystified by this, and I am reluctant to call him out given the last call he was here for 6 hours ($$$) and was unable to fix let alone diagnose the problem.

I am going to warranty the boiler due to the leak, but I do not want to go to the effort of reinstallation without addressing this problem (unless the soot is caused by the leak).

Has anybody else encountered this problem?

Thanks!

bburd

Does the burner have adequate combustion air? In a very tight house, this cannot just be assumed. Clothes dryers and exhaust fans can put a house under negative air pressure and cause insufficient draft through the boiler if there isn’t enough fresh makeup air. It’s not difficult to add if necessary, the easiest solution is usually a “fan in a can“.

HVACNUT

Beckett OEM spec for that boiler is a .50 45°B at 150 psi with the L2 head. 
A tech who walks into a soot disaster on a 2 year old system and can't figure it out after 6 hours is not a tech. Ask your service provider to send someone qualified. 

As far as the block leaking, it's not a knock down boiler. Did the sections need to be disassembled for installation?

ineffable

Thanks, bburd. I had a blower door test done on the house; it's actually -- unfortunately -- very leaky, especially the basement.

HVACNUT, thanks for the specs. I'll reach out and see if I can get somebody better and who installs the right part.

The boiler came assembled and was never taken apart so I must just have gotten a bad one.

EdTheHeaterMan

ineffable said:

Thanks, bburd. I had a blower door test done on the house; it's actually -- unfortunately -- very leaky, especially the basement.

HVACNUT, thanks for the specs. I'll reach out and see if I can get somebody better and who installs the right part.

The boiler came assembled and was never taken apart so I must just have gotten a bad one.

This is truly unfortunate. The problem with your situation is the boiler manufacturer only warranties the boiler, not the labor. Since it is within the first 2 years you may be able to get the Buderus to anti up some extra $$$ for install if you make enough noise. They have always been good to me when I was dealing with them. (New Rep since then so I have no inside contacts to offer)

The original installer may also be helpful in perhaps a discounted price for the boiler replacement. If you are lucky you may get a better deal than if you just acquiesce to the written warranty.

The water in the boiler combustion chamber may be the problem. You won't know until that is fixed. But if that is the only difference in the operation between the first season and the problem season, that is where I would start.

Best of luck with your situation. BTW buy a lottery ticket on Thursday. You know, Shamrocks and Leprechauns and all

Mr.Ed

ineffable

Thank you everybody for your suggestions.

After spending $1100 on boiler techs and chimney sweeps to determine what the problem was, Buderus then required the tech to come out again to confirm what he had already discovered. They made him wait on a callback on site, creating an unnecessary $500 service charge for me.

Buderus then sat on the warranty request for three weeks, now want a $200 warranty processing fee, and will only provide the block, meaning the boiler will have to be disassembled and reassembled. Per my installer, this will cost $6000 in labor.

This has been an awful experience.

Jamie Hall

Sad. You decided it was the boiler and Buderus' fault. It wasn't. It was a tech. who couldn't -- or wouldn't -- clean and properly adjust the burner. Having decided it was a faulty boiler, and not poor service, I'm not surprised at the results...

ineffable

The tech was extremely thorough in cleaning the system. I can vouch for that. This tech did properly set up the boiler in the past; he could not get it to work this time.

The section seal is leaking -- as evidenced by a puddle of water, right on top of the seal, in the combustion chamber. Mop it up and the puddle will reform, with no water anywhere else. The boiler was determined to be faulty because it is.

I can't say that the puddle in the chamber is responsible for startup problems but it seems plausible.

Jamie Hall

I'm not doubting that the boiler is -- or was -- leaking. A leak is a leak is a leak. "Faulty", however, is a very tricky -- and loaded -- term, and requires proof as to proximate cause, which I haven't seen.

That said, a leak -- unless it is a real cascade or spray directly into the fire chamber -- will not cause combustion problems which cannot be overcome. Consider: it is remarkably difficult to put out a fuel fed fire -- or even discourage it much -- with anything much less than a fire hose size water supply. Ask you fire department...