Boiler smoking like crazy

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PanteraMatt

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I have an old Weil McLain. My wife was in our basement yesterday and noticed it had a strong odor. I went down later in the day and noticed there was a lot of soot in the boiler and pipes and I just had it serviced. Then when it kicked on it POURED black smoke and the fire box was way too hot like there was too much flame, it actually was coming out of the peep hole. It's also very loud. Is there anything I can check?
 

Dana

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An oil fired beast, right?

Make sure the flue isn't obstructed with a bird nest, spalling masonry (assuming it doesn't have stainless liner) or a dead raccoon or something. If it's all clear, make sure it has the manufacturer's recommended jet sizing on the burner, or just call back the tech to re-tune the thing, or even down-size the jet (to within manufacturer's parameters), since nearly all oil boilers are ridiculously oversized for the space heating loads, causing it to run at a low duty cycle and poor AFUE. They may have installed the wrong jet, or failed to properly adjust the air/fuel mixture.

Oil burner mixture & combustion efficiency usually drifts over the course of a couple of years, and it's not crazy to have somebody with the experience & combustion analyzer tools to dial it back in at least every other year, if not annually. It's not rare to find an 85% efficiency boiler running at 75% combustion efficiency after a few years of benign neglect. But once it has been tuned and serviced you shouldn't have problems of this magnitude for years unless they screwed it up , or maybe your chimney is clogged/collapsing.
 

Dana

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You're just assuming it's firing too much, which it may or may not be. If the flue is clogged the air drafting through the burner goes to the slightly fuel rich (= smokier) level, and the flames the combustion chamber becomes pressurized, with the potential for flames coming out of other places. This isn't something you want to mess with. But since you asked for something to check that might contribute to those symptoms, a blocked flue is something that you can check for without firing the boiler that could contribute to soot and smoke pouring into the basement.

Most oil boilers on masonry chimneys have barometric dampers on the venting to dilute the exhaust with room air to lower the risk of flue condensation. If that is stuck/jammed such that it doesn't swing freely, that too could contribute to the problem somewhat. If it swings freely when tapped by a finger, but doesn't appear to open or open only slightly when the burner is firing it could be an indication of a constricted flue.

The round thing sticking of the side of the vent pipe is a barometric damper (which the tech should have tested and adjusted during an annual/bi-annual service)

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PanteraMatt

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Yes I have a damper and it swings free as I checked it last night by pushing on it. I did not check its movement with the boiler firing though as smoke quickly filled the room. SO, when I get home I'll climb on my roof and check the chimney for an obstruction. Anything else I can check while I'm at it?
 

Dana

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If it's a straight shot from the damper to the chimney (as it is in the example pic above) you may be able to see if spalling chimney crud has blocked or partially blocked where the vent pipe enters. You'll need a mirror on a stick and a good flashlight. If the chimney flue is super-straight you might be able to see daylight with the mirror too, without having to climb up on the roof.
 

PanteraMatt

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Looks like the chimney was plugged. For some reason he also fully tuned it which he just did but whatever. He said the end cone was worn and the combustion chamber was deteriorating and said parts were not available. Can I find these parts cause I don't plan on living in this house too much longer so I don't want to dump anymore $ into it.
 

Dana

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I'm not the right person to assess parts availability, but it's impossible to even guess without a model number for the boiler & burner to refer to. If the thing predates the Nixon administration it could be tough.

But if the flue is clear and the thing tests at 70% steady state efficiency or better there's no reason to believe it's in imminent danger of falling apart, even if it's clearly wearing out.

If the guy tuned it there should be on a tag with the date of service on the boiler or burner with at least some of the combustion analyzer data on it, including it's efficiency. If it's steady-state efficiency is much lower than 70% it's probably worth coming up with a plan-B. New, right-sized HVAC equipment will make it easier to sell, is often subsidized by state efficiency programs (sometimes on financing, sometimes rebates, or even both), and can will save you on operating costs while you're there. If you're moving out before spring, don't bother, but if you're thinking you'll be moving in spring 2020 it's worth considering, especially if NJ will subsidize the work in any fashion.
 

Jimna01

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Was this smoking before you had the tech come out? If it wasn't then he needs to come back and complete the tune up properly and use the appropriate combustion analyzer tools to properly adjust the burner . He did not complete the job properly . Maybe it's worn out beyond ideal repair but if it's smoking in the basement it needs to be adjusted or the minimal repairs completed so it doesn't' .

I know you said you are moving soon and don't want to spend a lot of money. I am not sure what is customary in your area but I if we're looking at your house as a potential purchase and saw a boiler in this condition I would as a condition of sale expect you to replace the boiler or make allowance on the sale price for the cost of a new boiler, incidentals and installation . I the buyer would likely choose the later so I could choose one to my liking . So it may be cheaper for you to replace it now before you put your house on the market and perhaps choose a lesser boiler which won't be as expensive for you as the amount I may ask for compensation. That way you can put the house on the market with the claim of new boiler which should help your listing price .
 
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