Flakes inside forced air heater

[dperry]

Hi everyone,

I'm not an inspector but have noticed an issue with my gas heater so I hope you won't mind me posting here about it.

I have an old Holly (like Williams) gas forced air wall furnace and today I noticed a small pile of flakes in the vent at the top of the unit, below the blower. I assume this is probably the flue vent. The flakes are rusty on one side and sort of dull metallic silver-grey on the other and they instantly turn to dust when touched. There's also a lot of dust around them.

Their proximity to the intake blower is what concerns me since they are so light and dusty and because of the age of this thing and the likelihood of lead paint. God forbid if some lead dust got sucked in and blown all over my living room. However, I'm thinking this may be cold galvanizing compound/paint, which is used to treat steel in corrosive conditions. In that case, it would be mostly zinc. I don't know about lead content, though.

Unfortunately, it looks like these Williams-type wall furnaces have no filter. I'd like to know what most likely origin of the flakes is and if they are anything to be concerned about. I can only guess at the age of the furnace but it looks '60's.

Thanks in advance for any advice you can give.

Dave

[kurt]

The older Williams have an open heat exchanger; the bottom isn't sealed. Air blowing across the heat exchanger can pull combustion gas out, and into the room.

That means folks can get sick, or die. If I had one of those, I'd tear it out and replace it.

I don't know about the flue dust, though. Not without a picture.

[Jim Katen]

Hi everyone,

I'm not an inspector but have noticed an issue with my gas heater so I hope you won't mind me posting here about it.

I have an old Holly (like Williams) gas forced air wall furnace and today I noticed a small pile of flakes in the vent at the top of the unit, below the blower. I assume this is probably the flue vent. The flakes are rusty on one side and sort of dull metallic silver-grey on the other and they instantly turn to dust when touched. There's also a lot of dust around them.

What you describe sounds like a form of soot that's formed on the interior of the vent. After a time, especially if someone knocks on the vent, this soot will flake off and fall out. If you pick up a piece and rub it between your fingers, it feels like very fine powder, not gritty. If that's what it is, it's a sign that your flame is poorly adjusted.

Their proximity to the intake blower is what concerns me since they are so light and dusty and because of the age of this thing and the likelihood of lead paint. God forbid if some lead dust got sucked in and blown all over my living room. However, I'm thinking this may be cold galvanizing compound/paint, which is used to treat steel in corrosive conditions. In that case, it would be mostly zinc. I don't know about lead content, though.

If it's flakes from the zinc coating, it will feel gritty -- like rubbing rust between your fingers. I wouldn't worry about lead here. If you want to worry about lead, look at the painted woodwork in the house and look for places where it's abraded such as windows & doors.

Unfortunately, it looks like these Williams-type wall furnaces have no filter. I'd like to know what most likely origin of the flakes is and if they are anything to be concerned about. I can only guess at the age of the furnace but it looks '60's.

I think the flakes are harmless. Vacuum them up.

Kurt mentioned one hazard of these furnaces. Another is that the heat exchanger might be cracked. If you're a handy sort of person, get a screwdriver and remove the outer metal cabinet. Then look carefully at the heat exchanger. It'll look like a tall, rectangular metal tube. Use a mirror and a strong flashlight to look at the back as well. You're looking for holes, cracks, or separations at the joints. I find them all the time. Some pictures are attached.

If you find holes, cracks, or separtions, it's time for a new furnace.

If you don't, hire a HVAC tech to come out, clean up, and tune-up your burners. Then install a carbon monoxide alarm.

- Jim Katen, Oregon

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[dperry]

Jim, thanks so much for the detailed reply.

A repairman on another forum said he thought the flakes seemed like what he called "silver paint" from the draft hood, which got me worried, but the only thing that would fit that description that would make any sense in this context would be galvanizing compound, and my research hasn't given me any indication that it would contain lead.

The rust on one side indicates iron, but the dull silver on the other side made me feel it was something other than soot. The fine dust accumulated in that area does have a dark color, though.

Thanks to both of you for the warnings about the age of the furnace---this is a rental property and the landlord will definitely be notified about the unit and asked to have it inspected before I start using it again this fall (the blower also started squeaking badly so it may be time to demand that the whole furnace be replaced). I've stopped running it though, so my main concern was whether I was going to have to do a very thorough cleaning of my entire living room in order to remove leaded dust that had blown around. I'm not as concerned about that now, though, so thanks for that.

BTW, cheers from a fellow Oregonian! [:-thumbu]