Ice on the cap...

[Slow1]

About 9* outside as I left for work. House nice and comfortable - had a beautiful fire going for the day. Looked at the stack and saw a bit of steam blowing and icicles growing off the bottom of the cap - looked to be pretty clear ice from the road, will have to check out the color when they fall off to see how clean they really are.

Then driving to work I passed another burner often times is billowing smoke (his cap looks to be dripping with creosote about this time of the year). He too had ice on the cap, but it looked to be very dark brown, almost black and significantly more of it.

So ice on the cap must be fairly common in this cold weather - I wonder if it implies anything about what is going on inside my exterior SS pipe etc. Thoughts? Opinions?

 

[Jags]

Hmmm...If you are getting ice, you know the cap is not very warm and the pipe up there isn't gonna be very warm either. Might be time to inspect. What type of stack temps are you running?

 

[Highbeam]

Ice on the cap even happens here in the NW. The cap is a single layer of SS and even with a hot flue interior, it might not see much heat. The flue is insulated pretty well.

Here is mine with ice when burning the heritage non-cat which sent huge amounts of heat up the flue. My flue temps are now 50% of what the heritage wasted so I expect even more ice.

 

[jharkin]

I've had icicles hanging down from the cap in previous years. Did not find unusual buildup up these in the annual cleaning.

 

[Slow1]

Hmmm...If you are getting ice, you know the cap is not very warm and the pipe up there isn't gonna be very warm either. Might be time to inspect. What type of stack temps are you running?

Surface temps on my double wall is reading around 150-175 about 18" above the stove. IF we accept the "triple the temp" argument then that would be something like 450-525 interior temps, but that would be an estimate.

Note that I've had ice in the past with the FV and never really worried about it. I do have more fluff at the top of the stack but I assume that is normal, but maybe that is just normal for me?

 

[PapaDave]

Older, non-EPA stove, and I get that even though I'm burning hot. Mine is light brown, which has to be due to more crap going up and out than a newer, cleaner burning stove.

 

[Jags]

Surface temps on my double wall is reading around 150-175 about 18" above the stove.

Surface temp of double wall means little to nothing. Very little correlation to any real temp going on. Heck, you are probably getting just as much radiant temp off of the stove as you are from the pipe.

Get a probe and work with the real numbers.

 

[Highbeam]

Since folks often get steam very near their caps we can assume that the temperature of the flue gas is nearly 250 at the cap.

Also, there is the possibility that the water which forms this ice is from precipitation perhaps falling as snow and then melting on the cap, running off, and forming icicles as it drops. You'll notice in my photo that I had ice on my gutters too.

My BK's owner's manual identifies the problem of ice forming inside the flue and/or cap to the extent that it blocks the flue. You are supposed to crank up the fire for awhile to melt your chimney.

 

[Jags]

You are supposed to crank up the fire for awhile to melt your chimney.

I know what you meant, but that sounds funny.

 

[DanCorcoran]

Just returned from the cabin. First time I 've noticed short (2-3") icicles hanging from the cap. I would occasionally hear them dropping onto the metal roof. Low yesterday morning was 3 degrees, high yesterday was 12, 4 degrees low this morning. I'm assuming it's just the unusually frigid temps that are causing it. I got very little creosote when I swept the chimney. I tried to get the flue temp up to around 1,000 degrees for a few minutes each day, then ran it in the "normal" range.