I may have a line on a decent catalyst woodstove. I've been burning wood for the last 7 years, but with an Avalon Rainier
non-catalyst model. We're adding a second stove and I have a line on an older Silent Flame model with a catalytic combustor. My question is - how does a catalyst stove perform on an overnight burn? I understand there needs to be a certain temperature to light-off the combustor, but what happens later when the fuel runs low while the combustor is still engaged? I know I will be doing overnight burns and want to be sure that a catalyst stove will perform well under those conditions.
I'd like to hear from anyone who has such a stove and uses it for heat
Don't have that model - have Woodstock Soapstone Classic w/catalytic burner.
My experience has been very good. Get plenty of heat, and if using hardwood, a good long burn - approx 8-9 hours or so overnight. I also burn pine (well cured, of course), but the burn time is a good bit less and I try to use hardwood overnight.
I have a sweep come annually (roof is too steep for my comfort - always cleaned the flue myself at the old house w/non-combustor stove) and he always says that the flue is in good shape. He does a thorough job but doesn't have much to get out.
Burning with a combustor takes a little getting used to, but is not difficult. I highly recommend a combustor probe of some kind rather than a surface mount thermometer to monitor the combustor. As I understand it, most stoves have a hole for such a probe.
The first year I had my stove I was using a surface mount thermometer and wound up with excessive creosote (compared to now, not compared to a non-combustor stove) because I was not able to tell (due to the thickness of the soapstone I was measuring the temp of) if the combustor had lit-off or gone out for a while after I engaged it. It doesn't always light-of the first try - depends on density of the smoke and exactly how hot the combustor and smoke is. A probe measuring the gasses coming out of the combustor will let you know when you should engage the combustor and you know almost immediately if the combustor lit-off or if you need to disengage it and let it heat up a little more. Using the surface mount thermometer caused my learning curve to be greatly exaggerated. Once I started using the probe, it didn't take long to figure out how to make things work properly. That may be different on an all-metal stove - never had one of those with a combustor in it.
Yes, the combustor needs a certain light-off temperature. I use an electronic probe made by Condar (model 9-86, see
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for more info) to determine when the proper temp is reached and to make sure that the combustor is burning after engaging. If the temp is borderline on light-off temp then the combustor may not stay lit the first try. It also provides an excellent indicator of when to reload - if you see the temp approaching the light-off temp, you can reload and not have to worry about the combustor going out - or if it does, it will light-off almost immediately after you reengage it.
One big thing to remember is not to get the combustor too hot too fast. If you get a roaring fire going as soon as possible, you'll probably crack your combustor. Should be some warning about that in the stove docs. Build up the fire over about 45 minutes or an hour to light-off temp. Refilling isn't so critical unless you've let the fire die back really low.
When the fuel runs low toward the end of a burn, there is not much creosote generating material left - I'm sure you've noticed that there isn't any or very much smoke from the coals in your other stove in the morning. Since there isn't much smoke, there isn't a problem with clogging the combustor - that would occur if you don't reach the light-off temp and engage the combustor anyway. Regardless, any buildup from the end of a burn is cooked off when you build up the fire in the morning and will accumulate (what isn't forced out by the smoke flowing through the combustor) in the honeycomb as fine powder.
I usually blow out the combustor with my shop vac every 4-6 weeks when I'm burning 24-7 - before I got the shop vac I just blew it out using a piece of
3/8" hose and lungpower. Be careful with the combustor when cleaning, they are rather fragile and not so cheap. I changed my combustor after 4 years (I figure that my mis-use of the combustor the first year really limited it's life) - YMMV.
My heating season isn't long - Northwest Ga - but I do use the heater 24-7 once cold weather sets in unless it gets really warm outside. I try to take advantage of warmer days to let the fire die to clean the combustor.
HTH
Later, Mike (substitute strickland in the obvious location to reply directly)
I bought a new high efficiency, hand fired Harman wood/coal stove a few years back. What is uses is a second set of air vents, in the door, below the glass, that are constantly open- they are just slits. This air enters the firebox above the fuel, and causes further combustion and a more complete burn, and less chimney emissions. It's really an emission control design- but what I found was, it's HIGHLY EFFICIENT at burning coal and wood. It squeezes every last available BTU out of the fuel- and also has a built in eletric fan to blow the heat out of the top through vents. It is hand stoked, so I have to load it with coal daily, and rake it down, and empty ashes about every 2-3 days. What is amazing about this stove is, it heats my home using only 2.5 tons of coal annually. I've been burning coal now for 12 years, and for $250 it heats the house all winter- through some very frigid Pa. USA winters. Typically I burn it from November to April, sometimes into May. With the recent spike in fuel costs, 3 ton of coal cost me $375 this year, but I won't even burn all that.
Another interesting fact- the draft control is a large knob that is 6 turns full out- I burn this stove at only 3/8 of a turn out with coal and it stays lit indefinitely and heats the house, as long as the fire is serviced. I have never had to open the draft further than 3/4 turn out, even during 20-30 below zero days. The stove basically burns 40 pounds of coal daily, on the coldest days- on warmer days in the
30-40's, one bucket (40 pounds) will last 2-3 days. I can't believe how efficient it is.
If the draft is opened up beyond 3/4 turn, and the fan turned on, we are opening upstairs windows to let heat OUT of the house in the dead of winter.
By comparison, I lugged 6 heaping truckloads of wood, loaded to the cab roof, full size F-150 8-ft box, to my relatives last month- they burn wood. It cost us $40 in gas to haul that wood- then it had to be split and stacked by them.
For the money, I'd prefer to spend the $300 and burn coal- the work involved transporting, splitting, and stacking the wood outweighs any cost savings, in my case.
My main system is electric baseboard, which I keep turned off all year.
Thanks Mike, One note - from what I've read, you should never "blow-out" a combustor to clean it. I read in two separate places that vacuuming is the only recommended method for clearing obstructions. Not sure if it matters, providing your careful about it, but I thought I'd pass it along... One other question - have you had to replace the combustor yet? I anticipate having to replace mine as soon as I take possession of the stove (I bought it from a neighbor who had it for 15 years). I found a replacement for $66 including shipping at
Vacuum, blow - both move some air through the honeycomb to clear the powder. You should be careful anytime you're doing something with the combustor it's pretty fragile. Not to be argumentative, but to provide you with the most info possible, I went to Woodstock Soapstone Company and looked up the tips on combustor care. See
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at the bottom of page 2 right hand column. It says that LOW pressure compressed air is ok and that canned air for cleaning computers is fine.
I would think that blowing or vacuuming with a shop vac would generate similar air flow rates - can't get the vac nozzle against the combustor on the sides with the openings anyway, unless I take it out of the cast iron cover and then I'd have to replace the gasket that seals around the combustor. If you'd like to actually see what I'm talking about, I'd be happy to take a couple of pix showing how the combustor is mounted and send them to you - send private email (see sig) if you do as this is not a newsgroup for pix.
BTW, that document may answer any questions you may still have about combustors. Although it's for Woodstock stoves in particular, the gist of it should apply to any stove with a combustor. Didn't occur to me or I would have sent the URL with my earlier reply.
You should also note that I had misused my combustor the first season due to my lack of knowledge about how they work and the problem measuring the temps through the soapstone stovetop (if you are unfamiliar with this type of stove, see
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The instructions say to measure the temp in the center of the left-hand panel on the top - they provided a thermometer that would normally stick onto a metal stove with a built-in magnet. Not the best type of thermometer, even for a metal stove, from what I've read.
The combustor would probably have lasted longer - I expect the new one to last a good bit longer.
The combustor temp probes also help determine when it's time to change the combustor by letting you know that the combustor isn't getting up to the high temps that it normally runs at - gives you time to get a new one before the old one completely fails.
If it hasn't been changed in that amount of time, I'm sure that it is no longer working. The above mentioned URL says that a combustor will last 4-5 years. I figure I should get a year or two more from it since my burn season is short - time will tell.
No, not too expensive, but still something you wouldn't want to shell out unnecessarily.
Later, Mike (substitute strickland in the obvious location to reply directly)
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