Chimney cap screen clogging

[JRP3]

There is a piece of screen attached horizontally covering the chimney opening that has been getting clogged up with creosote. The screen seems rather fine, the squares are 1/4 inch, and become clogged after about a week of burning, effectively stopping the draft. I have been mostly using well seasoned wood though the occasional green piece does get through. I do think I've been engaging the catalyst too soon and dampening it down too much so I'm adjusting that.
I guess the basic question being is that screen a normal thing to have in place? I've currently removed it because I'm tired of climbing up on the roof and it seems to clog up at night and smoke me out.

 

[swestall]

Better go with a standard cap, the openings are larger than 1/4 inch.. The clogging with creosote though is due to burning and the screen is just collecting what's coming up the stack; you are most likely getting creosote in the stack as well. You have to wait until the temps are up there to engage that CAT so it fires off, otherwise the entire stove is going to cool back down and you are going to get creosote in the CAT, stove, chimney, etc. You should see nothing but heat coming out the stack when it is burning correctly. That screen would not be a problem under those conditions, but I'd still recommend a good cap in its place.

 

[Sandor]

This topic comes up every year and its usually divided.... screen versus no screen.

I vote no screen.

 

[begreen]

Is this an exterior chimney? If the cap is clogging in one week after a thorough cleaning, you have a creosote problem. Removing the screen will fix the clogging problem, but not the creosote issue. As a compromise, how about cutting out every other screen division to make it a 1/2" screen instead?

 

[derbygreg]

I removed my screen and what a difference it made.

 

[WarmGuy]

Aren't the screens required by law in some states? I know I have to brush mine off every few months.

 

[JRP3]

Is this an exterior chimney? If the cap is clogging in one week after a thorough cleaning, you have a creosote problem. Removing the screen will fix the clogging problem, but not the creosote issue. As a compromise, how about cutting out every other screen division to make it a 1/2" screen instead?

Actually it's an interior chimney. Good sized chimney with 4 flues running through it. The other 3 have caps with screens around the caps, this one, for the insert, has a cap with the screen over the opening. I was thinking of trying a larger screen and maybe wrapping it around the sides of the cap like the other three.
This is my first year in the house and I think I've been under-firing the stove in the mild weather. It's an Earth stove insert with a catalyst and I've probably been engaging the cat too soon and damping it down too much.

 

[swestall]

That insert should have no smoke coming out the stack when the CAT is engaged correctly. Get to those conditions and then look at your thermometer temps as a guide for future proper operation. Good idea about replacing screen as you describe, and with CAT engaged correctly you won't have creosote at all.

 

[JRP3]

Question, what happens with the cat overnight when I've dampened it down for the long burn?

 

[swestall]

As long as it is engaged, it will continue to burn the smoke/gas. You can easily figure out if all is well by going out and looking at the stack with a Maglite to see if there is any smoke. No smoke, CAT engaged. After you do that for a while and you see the stovetop temp you will get use to it.