Black soot around gravity heat registers

anne29b

my house was built in 1925 and has the original Janitrol? gas gravity furnace.

I have owned the house for 12 yrs and was told at purchase to convert because gas bills would be bad but didn’t have the money while going thru a divorce. But she worked great! When power was out for days in Cleveland the year I moved in I was the only one with heat! My gas bills aren’t high. She heats great, but… this has been happening for the past year. Soot, and this was much worse. I cleaned and brushed inside box on side and so much soot came out. The side of furnace was black before I cleaned it. My registers all have black soot on walls.

I know everyone will tell me to replace her and if she’s dying of course I will but until lately she’s been more than fine. I love the way she heats. My house is never cold in winter. From the basement to the attic is warm. Occasionally when it REALLY windy the pilot which is easy to light may go out. I really don’t want to tear up the plaster walls with new heat ducts if it’s something that can be cleaned or fixed. A LOWES contractor is coming today and I’m sure I will hear “replace it lady”. Any expertise on gravity furnaces deeply appreciated.
Thanks Anne

mattmia2

can you show us the burner? you need someone that understands combustion to clean it and figure out why it is making soot. gas burners shouldn't make any soot. Could be the burners are clogged, could be that one of the gas controls has failed and the burner is severely under firing, could be the heat exchanger or combustion chamber have failed.

with all that soot comes a ton of carbon monoxide, it could kill you, someone that knows how to clean and adjust burners needs to fix that.

is that a bimetallic vent damper? get rid of that. especially with the return right next to the vent.

that furnace is probably from some where around the 50's.

the basement return next to the burner would not be allowed today because it is competing with the burner for air.

and get a good unlisted low level carbon monoxide detector.

Larry Weingarten

Hi @anne29b, @mattmia2 covered the points, but I'd like to focus on the soot. It is made in the combustion chamber, which should be completely separated from the air you breathe by a heat exchanger. That heat exchanger clearly is leaking. Older gravity furnaces sometimes had cast iron heat exchangers, so there could be the possibility of replacing a failed gasket. I've welded up cracked heat exchangers, but it's not a small job. Of course, there would be no soot if it were burning correctly, but the heat exchanger is the elephant in this room. The one thing I'd do immediately is to get low level carbon monoxide detectors and put them in bedrooms. Not to put too fine a point on it, but if the heat is on, you risk not waking up every morning. Currently you're doing 80 mph down the freeway and the steering wheel just fell off. 🙀

Yours, Larry

GGross

Yup the soot tells us your flue gas is going into your air ducts and that flue gas has a bunch of soot so it's extra bad to be breathing in. I would suspect some medical issues you might not even think about would clear up when you replace that with something that isn't pumping flue gas into your house. Like Larry said it might be possible to repair the heat exchanger, but I doubt you would find someone who would offer to do that as a service, too much liability for most shops to take on.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1861157#Comment_1861157

the fact that the return is on the side of the furnace makes me think it is possible the hx is ok and it is pulling soot up that way. either way there is a sever risk of CO poisoning. if the chimney is blocked it could be causing your combustion issues too.

Steamhead

https://forum.heatinghelp.com/discussion/comment/1861159#Comment_1861159

Could be that thermal "Lau-Vent" stack damper too, as @mattmia2 said. But I'd seriously consider replacing the whole unit, since something that old is probably rather inefficient.

EBEBRATT-Ed

your health is the most important thing. Yes it is more than likely tha Anyone you call will tell you to replace it due to its age.

the soot may be coming from a bad heat exchanger

It oils also be the soot from bad combustion is being pulled into the return duct

Either way someone needs to chek this out post your city and check find a contractor on this site

Some contractors will not want to work on this due to its age and the will not want the liability

JUGHNE

Those "Lau Vent" stack dampers failed after some time. And were not good for horizontal position. IMO.

You may have bad heat exchanger, but it could be only plugged exhaust vent causing flame/gases to roll out of the draft hood.

captainco

Stack Heating is one of the best. One of NCIs students

HVACNUT

Please check back in @anne29b. But turn off the gas and electric to the furnace first.