Spark Screen Question

[Nonprophet]

While I'm not normally very fond of spark screens, using a wood stove in a yurt means that we must use one as we have a vinyl fabric roof. We learned the hard way what can happen with a hot ember on a vinyl fabric roof two summers ago when we were burning some yard waste and the wind shifted and a burning leaf landed on the roof and burned a quarter-sized hole into the fabric before I could reach it with the water hose we had at the ready.....

Anyway, when I put in the wood stove I got a normal china hat from the local home builder supply store, and then made a spark screen with galvanized 1/4" mesh wire. It's been working just fine (no embers on the roof!), in part because we put the stove and pipe on the downwind side of the yurt. The only problem is that about once every 7-10 days I need to clean the spark screen with a telescoping paint roller handle with a wire brush taped on the end. It takes about 3 mins--simple, but effective.

We're just now replacing our older "smoke dragon" non-certified stove with a used VC Encore Cat. So, while I'm fine tuning everything and cleaning out the chimney, I was wondering about maybe going to a larger mesh size that wouldn't need to be cleaned so often--but maybe it's just not worth the risk.

What size mesh do folks here recommend for a DIY spark screen? It dawned on me that when using the cat any ember from the fire would be "filtered" by the catalyzer, but with the damper open there's still a risk of a hot ash/ember going up the flue and winding up on our roof.......

Any suggestions are greatly appreciated!

 

[Nonprophet]

Yes, we do have a fluepipe damper already installed--but usually when I'm trying get the fire started I have that all the way open in order to maximize the draw, so when it's open a spark/ember could still slip by.........

 

[Highbeam]

The only time that my stove makes sparks in the firebox is when a fresh load is ignited, especially during the kindling stage and of course nothing runs out the cap. Your cat will not be engaged during the most dangerous part of the cycle to filter sparks. 1/4" mesh is super tight. The stock sparkarrestors are way bigger, I think 3/8" min and 1/2" max.

 

[fossil]

As Highbeam said, the NFPA 211 description of a spark arrestor screen is one which will prevent the passage of anything larger than 1/2" diameter, but allow the passage of anything smaller than 3/8" diameter. I think the typical screens out there are 3/8" mesh. Mine are, and I don't normally need to clean them any more often than along with my annual sweep. I keep an eye on them, and they do collect soot/creosote accumulation, but they don't clog up to a point that my draft is seriously compromised. Rick

 

[Backwoods Savage]

I also agree to 1/2" minimum but 3/8" better. Clean them often.

 

[Nonprophet]

Thanks everyone--I really appreciate the help!