I guess I need a screen on my chimney

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blacktail

Minister of Fire
Sep 18, 2011
1,419
Western WA
I was burning some bank statements and junk male the other night. After the fire had been burning for a minute or two, this guy made his way onto the hearth. I thought it was a piece of charred paper and was about to scoop it back into the stove. When it started crawling I realized it was a bat suffering from smoke inhalation and 3rd degree burns. I whacked him and sent him back into the stove.
Will there be a noticeable change to my draft with a screen on the chimney?
 

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With my old smoke dragon insert and 13" x 18" tile flue I used to get birds and bats both nesting down my chimney and on top of my insert. I had an open top on the chimney at the time. I once looked down the chimney and saw a rotating black ball down there that turned out being an entire colony of bats all clinging to one another! I ended up making a wooden cap to put on top of my flue opening once I stopped burning for the season. With my new set up I have regular chimney caps with mesh coverings over the side openings.

As to your question about whether a screen on your cap will affect your draft: Yes, there is definitely some restriction to your draft with a screen over the opening. It's basic physics. You will be forcing the same amount of volume (gas and smoke) through a smaller opening (the existing opening minus the area now covered with screening - the solid part of the screen). As to whether or not this will hurt your draft enough to notice a difference in how your stove burns, that all depends on how good a draft you have now. I'd guess if you have a good draft there shouldn't be a problem since most stove burners use such a set up. If you have a weak or marginal draft it would of course make it that much worse. One thing for sure, once you have a screen covering the opening in your cap you will need to monitor it closely for creosote build up until you see how quickly or slowly it gathers on the screen. If you burn wet wood you'll get a very quick build up of creosote on the screen and that definitely will stop up your draft.
 
All chimneys should be capped... I once had a squirrel come down the fireplace.... That wasn't pretty...
 
I once had a bird in our wood stove during the summer months... I had just got done painting our ceiling in our living room... Well I opened the stove door very slowly , just enough to get my arm in to reach the bird... Out he shot , banging against my nice white ceiling leaving black ash marks all over;lol
 
There should be no noticeable change in draft from adding a screen, unless the screen builds up with ash/creosote.
Burning waste paper and junk mail is not something you will find applauded on here, but its your place do as you wish.
The ash from the paper may help clog a screen. Colored circulars etc. are considered even worse.
When choosing a screen, I suggest you use a material that has a larger hole size. 1/2" or larger openings would be best.
As noted already, keep an eye on the screen the first year of burning to keep it from getting clogged.

On another note, wacking the bat and putting it back in the stove to suffer is pretty heartless. Especially since it found its way in there due to someone being lax and not having a screen installed in the first place.
To each his own, but if it would not have survived releasing it outside, you may want to consider a lil more compassion and just put it out of it's misery quickly.

Bats are having a hard enough time surviving with white nose syndrome.
Some food for thought.
http://www.nwhc.usgs.gov/disease_information/white-nose_syndrome/
 
My wife once peeled a live bat from a fly paper strip we had hanging, without gloves! Got it freed enough so it could grab onto a tree, then we applied olive oil between the glue paper and the bat unit we could peel him free... I never forgot that! Never give up hope.. I first saw that, I figured he was doomed!
 
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On another note, wacking the bat and putting it back in the stove to suffer is pretty heartless. Especially since it found its way in there due to someone being lax and not having a screen installed in the first place.
To each his own, but if it would not have survived releasing it outside, you may want to consider a lil more compassion and just put it out of it's misery quickly.

The first thing I could grab was an alder round about 3" thick. He was very much dead when he went back into the stove.
Most junk paper goes into recycling, but any bank statements, credit card statements, or credit applications go up in smoke.
 
My grandfather used to only put a chimney cap on for the summer and take it off during burn season. But, I'd give it a try and see how you make out first. Just keep a good eye on it w/ a pair of binoculars to make sure it isn't plugging up that first winter.

If you burn good hot fires with dry wood, you shouldn't have a problem with creosote blocking it up so long as the mesh isn't too restrictive. However, watch burning that paper with the cap on as it could fly up and plug the mesh.
 
I have a 6" liner that was installed by the shop that sold me the insert. They never mentioned a screen. My stove drafts fine, though it can be a bit lazy sometimes during shoulder season. It should be easy enough to get a screen on there this weekend. If it hurts the draft I'll just fall back on a seasonal cover.
 
Go with a screen that has 3/4" openings and you should be good to go.
 
There should be no noticeable change in draft from adding a screen, unless the screen builds up with ash/creosote.
Burning waste paper and junk mail is not something you will find applauded on here, but its your place do as you wish.
The ash from the paper may help clog a screen. Colored circulars etc. are considered even worse.
When choosing a screen, I suggest you use a material that has a larger hole size. 1/2" or larger openings would be best.
As noted already, keep an eye on the screen the first year of burning to keep it from getting clogged.

On another note, wacking the bat and putting it back in the stove to suffer is pretty heartless. Especially since it found its way in there due to someone being lax and not having a screen installed in the first place.
To each his own, but if it would not have survived releasing it outside, you may want to consider a lil more compassion and just put it out of it's misery quickly.

Bats are having a hard enough time surviving with white nose syndrome.
Some food for thought.
http://www.nwhc.usgs.gov/disease_information/white-nose_syndrome/
That fungus is really terrible. Both the bat and bee populations are really on the decline.
 
I have a 6" liner that was installed by the shop that sold me the insert. They never mentioned a screen. My stove drafts fine, though it can be a bit lazy sometimes during shoulder season. It should be easy enough to get a screen on there this weekend. If it hurts the draft I'll just fall back on a seasonal cover.

It's pretty uncommon for liner caps to have mesh, that's why they didn't mention it. In fact, most caps even for class a no longer have mesh. Dura-Tech quit using it a few years ago because of the problems associated with it.

But, if you use dry wood and burn the stove properly there is no issues with the screen. Just make sure it's at least 5/8".
Your stove shop should have some SS mesh around, Excel makes it in a roll that you cut to fit. It works nice.
 
I have 2 Dura-Tech caps that both have a screen that came with them.
How are companies selling their product in the PNW and other areas that require cap screen by law?
 
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I used hardware cloth to make screens for my fireplace chimney. I checked them just last week, up on a ladder, and after ten years there was no soot build-up except a tiny dusting. No birds down the chimney since I made the screens. I have noted no decrease in draft, so any hampering of the air flow is very minor and of no consequence.
 
I have 2 Dura-Tech caps that both have a screen that came with them.
How are companies selling their product in the PNW and other areas that require cap screen by law?

Like I said, they used to come standard on 6" and 8". Not any more though.
 
They did not quit using it. The merely made it an optional item for purchase on the DuraTech cap, and still comes with the DuraPlus cap.
At least that is what 3 different web sites that sell the stuff note in their specs.
Regardless, the debate over screen vs no screen will go on like cat vs cat, ploy vs steel etc.
I have never had an issue with cap screen accept the first year I burned, and that was due to poor wood and my own operator error.
Never had a problem since.
I still believe anyone that can't burn with a screen without clogging it up, needs some more learning. No excuses for clogged screen, cap or pipe, period.
Burn dry wood properly, and there should be no issues.
 
They did not quit using it. The merely made it an optional item for purchase on the DuraTech cap, and still comes with the DuraPlus cap. At least that is what 3 different web sites that sell the stuff note in their specs.
I glad you did all that research!
If you notice I said it no longer comes standard and I never mentioned Dura-Plus at all. I mess with Dura-Tech nearly every day, so no lesson is necessary, I was simply trying to help answer the OP's question.
 
I put a screen on yesterday morning. Very easy. Someone gave me a whole roll of galvanized screen. Stainless would be better, but this was free. My chimney is super easy to access so as long as I can get a year out of it, replacing it will only take a few minutes.
 
It will be fine. I took the screens out of my caps when I got them because I was concerned about draft and accumulation and after a few years replace both with screened caps and haven't had any problems at all.

Looks like this one is solved and it is closing time.
 
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