Old Fireplace

[caryseidner]

I saw these high and low registers on either side of this old fireplace (the house was 100 years old). I am assuming that the high and low on the left-hand side, and the high and low on the right-hand side are connected by a duct creating a convection loop on both sides. Is that right?

I peered into the high registers and saw they were lined with asbestos. Is that common? Was the temperature passing through the ducts high enough to necessitate this? If so why was the asbestos inside the duct and not outside the duct.

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[Jim Katen]

Originally posted by caryseidner

I saw these high and low registers on either side of this old fireplace (the house was 100 years old). I am assuming that the high and low on the left-hand side, and the high and low on the right-hand side are connected by a duct creating a convection loop on both sides. Is that right?

I peered into the high registers and saw they were lined with asbestos. Is that common? Was the temperature passing through the ducts high enough to necessitate this? If so why was the asbestos inside the duct and not outside the duct.

That's a heatilator design. Actually, Heatilator is, I believe, a brand name of a prefab metal firebox with heating channels. Your example is just a masonry version. It works exactly as you guessed. Air enters in the low vents, is warmed by the back side of the firebox and rises out the upper vents. This design is extremely common in older homes.

I've never seen one with asbestos inside. From your pics, I don't believe that there's asbestos in the one you saw either. I think that's just mortar parging. There's really no need for asbestos in those passages because they're surrounded by masonry on all sides.

- Jim Katen, Oregon

[caryseidner]

Thanks Jim. I wish those pics would have turned out better. I could see the familiar checkerboard pattern in the grayish paper inside the duct. Maybe this pic is clearer.

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[Bill Kibbel]

That's a site-built, air-circulating fireplace. Heatilator is a factory-built version.

That is asbestos on the inside of the air-circulating ducts. Don't be surprised if the ducts were formed with wood - I've seen it.

[caryseidner]

I couldn't tell what the duct material was, but if it's wood, that would sure be a good reason to wrap the interior of it with asbestos. Thanks Bill!