How to tell when Fireview combustor needs to be replaced, and how I light the stove

[fourwheelcycle]

I have not been on this forum for a long time, since my Woodstock Soapstone Fireview was new and I was learning to use it properly. Now I have had five winters on it and I just bought a replacement combustor to have on hand when my original combustor needs to be replaced.

I would appreciate comments and advice from experienced combustor stove owners on how to tell when a combustor needs to be replaced. I remember when I first got my Fireview there were a lot of threads about combustors dying early, but mine has seemed to work fine right through the end of last winter.

I live near Woodstock Soapstone. When I picked up my new combustor they said the best way to tell when it needs to be replaced is to watch your stovetop thermometer. They said if you switch over to the combustor at 250 F and turn your damper down to about 1 the thermometer should go on up to 350 F or above if the combustor is still working properly. I use a long thermometer that goes in the back of my stove and measures the temperature in the flue exhaust area right behind the combustor. I switch over at about 700 F on that thermometer and my combustor usually glows bright red for a while right after I switch over and turn down the damper. The flue exhaust temp usually rises to 850 F or so after I switch over and then dies down to lower temps as the wood charge dies down to glowing coals.

My plan is to watch the two thermometers this winter and look for signs that one or both are not rising 100 degrees or more after I switch over to the combustor.

What do others think or suggest?


One other note on lighting my stove -

I use the great discount deals on unwrapped Super Cedar fire starters from Northwestern Fuels. I use 1/4 disk for each fire and I have found I can start fires with three or more full-sized splits and only a very small amount of kindling. I leave my door cracked 1/8 inch until the flue temp hits 700 F, then I close the door, switch over to the combustor, and turn down the damper to 1. On very cold days with really strong draft I turn down the damper to a little below 1.

 

[Woody Stover]

Yeah, the stock cat probe doesn't quite reach over the edge of the combustor so I had been using it to monitor temp near the flue exit. This usually runs pretty much parallel with the surface meter I have lying on the tee snout, about 6" behind the rear-vented flue exit. I recently ordered a Condar 3cx-9 probe (not on their website, last time I looked.) Slightly bending the probe, it should reach over the edge of the cat and give a better reading as to what the cat is doing. Cats will generally run 1000-1500 when engaged on a fresh load, on the other cat stoves I have run, then slowly drop as the burn progresses and there is less smoke to burn. I don't see much difference on the short probe when I engage the cat. I know cat temp is well over 1000 when glowing. Well, Condar sent me an 11" probe instead of the 9". I didn't contact them to ask what happened there. I can cut it off to 9" from what I understand, but it may erode quicker without the protective coating on the end, I don't know.
I start my stove about the same way; I use SuperCedars split into 7 pcs, 2 pcs per start. If the coals are pretty much gone, I start a top-down fire with smaller splits and kindling in the front/top of the box. This method may get the top of the stove up to temp a bit quicker, I don't know. I run the surface meter on the tee up to 600 or a little over, with the probe at about 900 or so. I cut the air to run at this level for about 10 min, then close the bypass. The stove top meter over the cat may only be reading 150 or so but the cat will glow pretty quickly as a rule. I run a little flame for a bit, then cut the air to between .5 and 1, and let 'er cruise with no flame. If the cat isn't glowing at some point, I'll go out and look at the stack to make sure there's no smoke.
Did you get the newer Dura-Foil steel combustor, then? I'm running the original ceramic cat in the Keystone right now, but ran a diesel-foil for a season or two, so I have maybe two seasons on each cat. You probably read about the diesel-foil cats that were failing early but both my ceramic and diesel still seem to be working OK. The diesel-foils warped and shriveled so I had to keep an eye on that and make sure I had enough interam gasket in there to seal to the cast combustor frame. The new Dura-Foil doesn't require the cast frame or interam gasket, but you use the shipping bolts to hold it in place against the cat opening gasket. From what I understand, when cat performance declines it will be harder to light off and will drop out sooner when not as many volatiles are coming off the wood later in the burn. I'd like to get a Dura-Foil for the Keystone in case I need it, but they are often out of stock and I haven't gotten one yet.
This diesel-foil hasn't shriveled or warped too badly.

Here is the probe and surface meter on the tee. I have a paper clip bent around the bolt on the face of the probe to mark 1000*. It's hard for me to see the face of the probe without a mirror in my fireplace setup, and the probe can rotate, so this gives me a view of the needle in relation to the 1000* mark.

I can see the Keystone cat when I'm sitting on the couch.

...and the bag and scoop for using piles of crumbs on a flat split, when I need to use 'em up.