Chimney Caps

[taskswap]

First winter in a new house... I have an exterior chimney on a basement indoor wood boiler, and I've gone to some effort to make sure I get a good draft with it all. Insulated stainless liner, etc. For the most part it's working out well. I've cleaned it once a month mostly to inspect it, and never seen more than the usual few millimeters of toasted creosote - the good powdery stuff, almost all soot, and never too much.

The problem I'm having is with my CAP. I'm getting all of my creosote buildup there. Today I was getting smoke in the house so I checked the draft and it was almost gone. Turns out the diamond-pattern mesh (about 1" square holes, give or take) in the cap was completely plugged up with creosote.

It looks kinda like this, although with a worm-screw clamp to fasten it on:

We've had a lot of wet, cool (very foggy) weather lately - unseasonally - and my theory is the cap itself is cold enough to condense it there. This is a non-EPA stove and that's not in the budget right now. And yes, the wood is dry (it's been warm so I'm burning the 22% stuff, not the 18% I'm saving for when the weather gets properly cold again, but it doesn't hiss when it burns). This is not a lot of creosote, mind you - in a three foot stove pipe it might only amount to a millimeter or so of buildup. It's just that there's a small surface area here on this grill, so it doesn't take that much to plug it up, if that's where it wants to stick.

I'm wondering what everybody else uses for a cap and if there might be a better product. Seems like if there's anything that's even a little "better" it might be an easy/cheap fix until I can afford a cleaner-burning stove...

 

[Iron Head]

I have the stainless steel Chinese Cap style without the mesh.
I do get creosote build on it but there is no mesh to get clogged up.
That mesh design looks kinda dumb.
I suppose it's meant to keep critters out.
But the easiest solution to get critters out of the flue systems is to fire up your stove.

 

[KindredSpiritzz]

Mines a slightly different type cap but i have the same problem. Seems like once a month i have to climb up on the roof and pound a hammer or rod on the cap to clean it off and open it back up. Next year i'll find a more open type cap and use chicken wire to critter proof it.

 

[kmcinms]

I'm running two different fireplace inserts with caps on both chimneys. The one insert that is free venting into the chimney flue, hardly ever gets creosote in it and never gets it on the cap.
The other insert has a cap on the stove feeding into a 10" SS flex tube with a SS cap on top of it. We get thick gooey creosote built up on that one.

 

[Fred Wright]

Yup, cool damp weather will cause creosote to accumulate on the cap screen. Our wood is reasonably dry, around 19 to 23% MC... and I still have to get out the extension ladder and climb with a wire brush to clear the screen at least once once during the burning season.

It's not as bad as long as the firewood doesn't go in the stove right after it's been rained on. Moisture in the exhaust will contribute to screen clogging.

The screen is actually a spark arrestor. It's there for a reason. It keeps out birds and tree rats, true. But I wouldn't suggest removing or modding it.

Caps are available without spark arrestor screens, designed for a good draft and critters can't get in.

Hope it helps.

 

[taskswap]

It's easy enough to clean, it's just not something I'd want my wife to have to do while I was away. It would be nice if I could rig up some "get through the day" emergency alternative. Getting up on the roof after a 4" snowfall wasn't my favorite job to do in a hurry. I wonder if maybe I could rig up a bit of chain and a rope hanging down the side of the chimney, something you could shake a bit from the ground and knock off the worst of it - enough to last to the weekend, anyway, if there was unexpected buildup.

Or maybe during the burning season I could switch caps. I'm not worried about critters in the middle of winter - mostly we get squirrels in the fall, and I can't imagine one trying to poke its head into a hot flue with the furnace going. In the summer I could put on a cap better designed to keep them out while it's cool. But I hear what you're saying about the spark arrestor, although I'm having trouble seeing how this actually serves that purpose. It's not like the arrestor in a chain saw - the holes are over 1" square. It wouldn't stop much short of a full-on chimney fire, and even then I have my doubts.

 

[zogger]

The only thing I could think of is a couple fast blasts with a pressure washer from the ground. maybe a long wand to get closer?

Our brick chimney is completely open to rain, etc and I just laid a 1/4 inch mesh piece of screen scrap over the top and weighted it down with some bricks. It hasnt clogged up yet, using it ..hmm this is the 7th winter.

The chimney seems quite old and I dont think it ever had any sort of cap.

I get some creosote but not much, I think because I dont run an exhaust damper. Stove is pretty much running wide open in use, I adjust heat output with size and species and just a little intake adjusting.

 

[stihly dan]

Just take the cap off. Some stoves suggest it, others say remove the mesh.

 

[Eric Modell]

We are old school, we do not use chimey caps. In the summer we put a bucket over the pipe. I would like to upgrade to a cap in the shoulder season, and no cap during the twenty four- seven burn season.

 

[whatscooking]

I have my own brush and keep a close eye on build up, years ago i had a flue fire. I burn two plus year old dried wood that has a roof over it, oak and other hard wood. I still get build up on the cap, the screen is long gone. I can see how the build up can happen, smoke hits the cold cap and over a short time build up happens and the cap slows down smoke comming out the top.. A few days ago i cleaned the pipe and have left the cap off to see what happens, with this drastic drop in temp comming and no rain in site i thought it would be a good time for a test. I would like a easy way of putting a tighter cap on when it rains.

 

[Encore]

When we used our stove exclusively, we would take the screen out. I had the same problem of the creosote building up on the screen.

You don't need the screen on there except in the warm months when you aren't using the stove. Its more to keep birds and squirrls and whatnot out of there.

Once we took ours out, we had no problems at all.

 

[BrokenToys]

I have a chimney cap similar to that on my flue pipe; we've gotten some random dumba$$ squirrels deciding my chimney looks like a nice place to live the first 3 years in our house.
I've gotten to use a long pool skimmer pole and sticking a wire brush in the end and scraping it if i see a lot of buildup; but it's once a season [maybe] since we burn our stove 24/7.

 

[Ayatollah]

The only thing I could think of is a couple fast blasts with a pressure washer from the ground. maybe a long wand to get closer?.

I wouldn't do that. A pressure washer at that distance isn't going to be effective at anything but delivering a fine mist that will drip down the chimney. You want that stuff off and out, not back down the pipe.


I have just seen that too much damper use when the fire was going severely increased the creosote build-up on our screen. We still got it before the install of the damper, but not as quickly. Now I only apply the damper when the fire turns to coals.

By the way, I have seen sparks and a few burning embers make their way up that pipe. That screen may also keep you from starting a fire on a pile of leaves in your roof peak, gutters, or back yard.

 

[allstihl]

i threw out my cap 17 yrs ago

 

[taskswap]

By the way, I have seen sparks and a few burning embers make their way up that pipe. That screen may also keep you from starting a fire on a pile of leaves in your roof peak, gutters, or back yard.

In principle I would agree. But in practice, I think the holes in the screen are so large as to make that use ineffective (the screen probably covers 1% of the total surface area of the exhaust - until it's covered with creosote, anyway... which probably creates the exact risk you're describing).

More important, here in CT everything is covered with snow and ice. You couldn't start a fire out here with a blowtorch. We ran out of "small stuff" (twigs for kindling) the other day and were stuck until we split some from dried firewood, because they're so damp even if we collected more twigs they wouldn't burn. That doesn't mean chimney safety isn't important, but in my judgment removing the screen for the burning months is worth a try.

 

[MISERY]

I clean my cap from inside the house with a SootEater. Much easier and safer than going on the roof.

 

[taskswap]

That's a nice looking system. I can't use it because I have three 90-degree bends, one of which is "permanent" (inside the chimney, a Tee and and a long Snout). I already have a decent set of fiberglass rods and brush, but if I didn't I might get this setup. It's not very expensive and I like the snap-together connectors. I'd need extra rods, though, I have a 30' chimney.

 

[mizzou]

By the way, I have seen sparks and a few burning embers make their way up that pipe. That screen may also keep you from starting a fire on a pile of leaves in your roof peak, gutters, or back yard.

No. Had a flue fire a couple of weeks ago and the screen didn't stop hardly anything.

 

[Preston]

Yup, cool damp weather will cause creosote to accumulate on the cap screen. Our wood is reasonably dry, around 19 to 23% MC... and I still have to get out the extension ladder and climb with a wire brush to clear the screen at least once once during the burning season.

It's not as bad as long as the firewood doesn't go in the stove right after it's been rained on. Moisture in the exhaust will contribute to screen clogging.

The screen is actually a spark arrestor. It's there for a reason. It keeps out birds and tree rats, true. But I wouldn't suggest removing or modding it.

Caps are available without spark arrestor screens, designed for a good draft and critters can't get in.

Hope it helps.

I would like to see a cap the birds and snakes can't go through without the screen. My biggest problem is during the summer is the swallows wanting to build in the chimney. I have have a snake drop in once though. I can't keep a fire going all the time cuz here in middle Georgia during the summer it's just to damn hot.

 

[taskswap]

I would like to see a cap the birds and snakes can't go through without the screen. My biggest problem is during the summer is the swallows wanting to build in the chimney. I have have a snake drop in once though. I can't keep a fire going all the time cuz here in middle Georgia during the summer it's just to damn hot.

I tell you what, I thought squirrels were annoying. It never occurred to me to worry about snakes! I don't really MIND those things but I'm not a great fan, either, and let me tell you, the wife would FREAK if she found one in the wood stove at the start of the season! I guess I'll stop #####ing about squirrels.