Sand insulated flue pipe?

zepfan

Just starting working in a neighborhood that was built 20 years ago. All the homes have a  5” hart Cooley b vent stack and a 75-80 mbh input furnace, an an electric water heater. One homeowner is convinced that they used sand to insulate in between the aluminum inner section, and galvanized outer section. They are stating this because they see sand like pellets around  the flue collar of the furnace. They said it gets in the burners before the furnace cycles on, and  causes the furnace to lock out.

I have never heard of anything being used as an insulator, and normally see these white sand like pellets caused by single wall pipe pipe being run to the furnace, something with soap or lint in the furnaces combustion zone, or an oversized main stack. The stack could have been 4”, seeing how the water heater is electric . I have proposed replacing the single wall pipe that runs from the main vent, with B Vent to the furnace. The furnace is draft induced. 

The one homeowner is convinced the main B Vent stack is ruined because it was filled with sand. Again I have never heard of this, and replacing the main stack would be  a lot more work and cost. Has anyone else seen this condition? If so what was the cause and solution? Thanks to all

EBEBRATT-Ed

May not be "B" vent it could ben "L" vent "metalbestoes" used on oil and other fuels. I think some of those did have some type of sand like insulation in them.

Jamie Hall

But it wouldn't have been sand -- vermiculite is a possibility. Sand is a miserable insulator.

neilc

and vermiculite "could" have asbestos in it,
just sayin,

Mad Dog_2

Very odd.  Mad Dog 🐕 

kcopp

What are the odds the B vent was installed upside down?
What brand is it?
B-vent just is an air space... Galvy outside, Aluminum inside. Sounds like there a local myth started by someone and it gets passed on.
The sand part could be sand blowing in the area and making its way down the chimney.

realliveplumber

Its most likely corrosion. We see it frequently when the vent isnt the correct size.