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55 y/o gas boiler - smell, percolating sound, and now CO

Jason777 Member Posts: 1
My natural gas boiler is the house's original - 55 years old.

For about a month now there's been a bit of a smell when it's on - not overbearing, but noticeable. It's also been making percolating sounds - more of a stovetop coffee pot brewing than popcorn in the microwave.

For about 1.5 weeks now the CO detector has been going off when the boiler is on. Purchased a new CO detector - same thing.

It's on a ground floor utility room with front and back windows, and keeping the windows open was keeping it ventilated enough to prevent CO build up. The last few days it's gotten worse, and even a pedestal fan blowing toward the window isn't enough to keep the CO detector from going off.

The boiler now runs about 20 minutes before the detector goes off.

The flame seen from beneath are burning yellow, which I read means the boiler isn't burning the gas effectively, and causing CO.

It's the end of the heating season, and I go without it for a couple of weeks more. I'd rather replace it in the fall when it will operating more regularly, in case there's a problem with it in the weeks following installation. If I replace it now, I'll be stuck for a repair bill if it fails in some way in say, November.

The unit is 250,000 BTUs, and a guy that came out a few years ago measured all the baseboard radiators, and said the house only required a 125,000 BTU unit. He said gas was cheap in the '60s and they figured bigger was better - hence the overkill.

Is that true?

Is there way to be certain the boiler's problems aren't the result of a venting problem rather than the boiler itself?

The unit is so old, and it's a 3-zone system, that the kids that come out to look it (for things in the past), don't even know what they're looking at.

Should I be looking for a plumber rather than an HVAC person?

I don't know anything about boilers or plumbing, and have heard horror stories from others with some local contractors.

What would something like this cost, approximately in upstate New York?

I know if you get 90% efficiency you need additional venting, and it's more expensive - so I'd probably go with the 85% one. I'm sure I'll cut my heating bill by 60% either way.

Are there brands known to be better than others - or ones to avoid?

How can I find an older guy that knows what he's doing? Are there certain things I should be asking for?


    HVACNUT Member Posts: 5,025
    Yesterday was April fools day. It's no where near funny in any case.
    Shut off the gas.
    Shut off the electric.
    A pro needs to check the boiler and chimney draft.
    If you need a new boiler, well you need a new boiler. If those headaches get any worse you wont be around in the fall to keep our trades working.
    No pricing is discussed here.
    Click on find a contractor in your area at the top of the page. Maybe someone here can help.
    No offense but you should have addressed this a long time ago.
    STEVEusaPASTEAM DOCTORIntplm.HotanCool
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,131
    edited April 2019
    I'd immediately stop using that boiler until you solve your CO problem. Just leaving a window open isn't going to do it as CO builds up in your body quickly, and dissipates slowly-so you won't completely clear your body of CO while the boiler is off. You have to determine, among other things, do you have a blocked flue, blocked heat exchanger, negative draft situation, flame roll out, lack of combustion air-or a combination of things.

    I'd prefer an HVAC person versed in hydronics & combustion over 'just a plumber'. "Just a plumber" tend to oversize, cut supply/return and swap out the unit. Don't necessarily understand near boiler piping (and optimizing), newer equipment, proper sizing, newer controls, proper air elimination, etc.
    You might not even need it to be 3 zones, maybe trv's or zone valves (hopefully not 3 energy hogging circulators).

    I'd also prefer you get a proper heat loss (not just measure radiation) to get an accurate boiler size. Yes bigger is never better.

    You should replace it now or early summer before AC season kicks in. If you wait until fall, good people tend to be too busy, and then you're rushing it in because it's getting cold.
    A good contractor will give you a warranty. If it were me, I'd even come back when you first turn it on and check the operation, water/pressure level, and do a combustion test.
    EBEBRATT-Ed Member Posts: 13,435
    I don't mean to sound harsh but don't you read the papers? CO kills people. You have a CO detector going off you know what you have.

    Shut that thing off your harming yourself and your family.

    CO poisioning is cumulative. What happens if you don't wake up tomorrow?
  • Steamhead
    Steamhead Member Posts: 15,988
    @Jason777 , where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • DZoro
    DZoro Member Posts: 1,048
    All great advice, shut it down. (hopefully you already have)
    Yes 250,000, too big.
    The guy who does a heat loss, measures radiators, calculated needed water temperature at design load (worst case cold) . That guy (s) should be in the running for your business.
    When those are known numbers then you can start looking at what class boiler, 95%, or 85%...…
  • Jamie Hall
    Jamie Hall Member Posts: 21,102
    Steamhead said:

    @Jason777 , where are you located?

    Indeed. "Upstate New York" is not a useful term, really -- to a guy in Brooklyn it means White Plains. To a guy in Syracues, it means Watertown.. so. What town are you in?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • HotanCool
    HotanCool Member Posts: 54
    Sounds more concerned with money over safety! Any reputable Contractor will stand behind his install less than a year old. Do it now! Sizing a Boiler requires more than measuring baseboards.