Falling Ice

KDF

I have an older low efficiency natural gas furnace in a basement with the exhaust chimney out the top of a two story house. The chimney drips and forms ice on the chimney chase cover, it is never close to ever blocking the chimney but when warmer temps come these ice stalagmites fall and damage my neighbor's house. I don’t think this is anything new, it appears it has been this way since the house was built ~20 years ago. The only solution I can think of is heat tracing, but that is no easy task given the location. I also can’t get up there in the winter to knock them down. Any other ideas?

Larry Weingarten

Hi, Could you post some photos of the chimney top and the surrounding roof? I think that would help us get a better picture of what’s going on and how to fix it.
Yours, Larry

HomerJSmith

Is "Falling Ice" related to that Indian "Falling Rock"? Just asking.

KDF

Here is a pic from the ground, pretty icy up there this week. Should be better next week so I can get a closer pic. Of course, there are no large icicles at the moment. I appreciate any ideas you may have.

EdTheHeaterMan

HomerJSmith said:

Is "Falling Ice" related to that Indian "Falling Rock"? Just asking.

Did your father tell you about that missing American Indian baby Falling Rock also?
Such a tragedy back in the 1950s when that baby went missing. The entire country was on alert for Falling Rock. All the highway departments across the country helped, by posted signs to Look For Falling Rocks, or Watch for Falling Rocks.

I don't believe they ever found the missing baby. He is probably over 70 years old by now... if he survived

Larry Weingarten

Hi @KDF , I'm guessing the icicles are forming at the edge of the chimney top? If so, would wrapping that edge with chicken wire be something the ice could form in and around? If it did, it would have to melt to escape, so big chunks couldn't fall on your neighbor. Just an ugly thought...

Yours, Larry

psb75

Maybe rather than that flat metal surface on the larger chimney, have something fabricated with "some" pitch/slope to all four sides. I guess that would be..."pyramidal" with the stack coming out of the apex.
A "fun project" for a good "tin-knocker."

HomerJSmith

I would think that the chase and the chimney metal are too exposed to the cold environment and condensing is occurring just as soon as the flue gasses leave the chimney. I would insulate the metal flue pipe as much as possible, starting in the attic, chase, and then the flue itself. To keep the flue gasses a hot as possible.

I would remove the cap and storm collar and cover the existing flue with a larger 26 ga , conductor pipe at least 2" larger than the existing flue and place it over the flue, center it and fill it with non expanding foam (window and door foam) and put the storm collar and cap back on.

EdTheHeaterMan

A next size larger flashing with a same size storm collar may offer you a place to spray foam with non expanding window and door insulation as shown in this illustration

https://www.supplyhouse.com/Hart-Cooley-16320-6-Gas-B-Vent-Storm-Collar

https://www.supplyhouse.com/Hart-Cooley-16415-7-RTF-Tall-Cone-Flashing


Also use some high temperature pipe insulation to keep the B-Vent warmer in the attic.
https://www.amazon.com/JZWJH-Insulation-Fiberglass-Steam-Thickness/dp/B09L7K2XHD/ref=sr_1_75?crid=L8DJAHJNC6XL&keywords=fiberglass+pipe+insulation+7"&qid=1666802689&refinements=p_n_availability:2661601011&rnid=2661599011&sprefix=fiberglass+pipe+insulation+7+,aps,135&sr=8-75&ufe=app_do:amzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc&th=1
I believe you have 6" B vent but you must measure the outside circumference, then convert it to a diameter. The outside diameter of B vent is usually 1" larger than the inside diameter of the pipe. B-vent is sized by the inside diameter.

For example: If your B vent in the attic has a 22" to 24" circumference you would divide the circumference (lets pick 23") by 3.1428. That will equal about 7.3". By subtracting 1" from 7.3" you get 6.3" The closest B-Vent size to 6.3" is 6". so when purchasing B vent parts use 6" as the size. Use the 7.3" outside diameter for purchasing the pipe insulation. Purchase a pipe insulation that has a larger inside diameter that 7.3"

Your actual measurements may be different. Batteries not included. Some assembly required. Your actual milage may vary. Save the instructions. Do not call the store if you have a problem with this product. Void where prohibited.

pedmec

what type of equipment is venting into the chimney? A furnace is warm air and boiler is hot water