On 8 Nov 2005 21:38:00 -0800, northcountry wrote:
We're adding a second stove and I have a line on an older Silent Flame
model with a catalytic combustor.
Don't have that model - have Woodstock Soapstone Classic w/catalytic burner.
My question is - how does a catalyst stove perform on an overnight
burn?
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.
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?
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
http://www.condar.com/meters.html 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.
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
24-7.
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)
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