Metallic/rusty flakes inside gas forced air heater

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 recently 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 dark colored dust around them.

Someone on another message board said he thought it sounded like the “silver paint” from the inside of the draft hood, which got me worried about lead content. But a little research led me to believe it would more likely be flakes of zinc based corrosion resistant coating. Does that sound more likely than paint?

Do you think lead content is anything to be worried about here? Their proximity to the intake blower is what concerns me since they are so light and dusty.God forbid if some lead dust got sucked in and blown all over my living room. BTW, I haven’t used the heater since discovering this.

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.


Condensation issue possibly.
This can mean an improper air/ fuel mix or a flue issue.
There are other problems also that it could be.
You need to call an HVAC guy.

There should not be paint in a HVAC unit.(so I doubt lead is your main worry).

Bob, thanks very much for the reply. Ventilation in the house is generally poor and it rains a lot here in Oregon so I’m sure there are moisture issues. This is a rental so the landlord will have to deal with it before next winter. I mainly wanted to dispel the lead concern since this didn’t look like simple soot or strictly rust (although it is rusty on one side).

I don’t know how long this stuff was accumulating and possibly getting into the blower so I got pretty worried.

I looked quite a bit online and couldn’t find any evidence of lead being present in any kind of (zinc) galvanizing substance, if that’s what this is.

Thanks again for you comment.


At the very least go to the hardware store and get a Carbon Monoxide Alarm and install it in the house…for your safety.