Exhaust temps, Catalytic stoves

BK propaganda says 150° to 300° exhaust temperatures for normal operation.

Just too these pics of my stove pipe.
2.5 stat setting, fire from last nights 10pm load still producing heat
keep up with the 20° OAT, 10 mph wind.


Laid my hand on the pipe for about 2 seconds


My foil over the joints
I found leaks on the sliding joint sliding part & where it connects to the 45°

 

The wood splits :

My fire wood test.
3 year seasoned birch.
If I'm home I lay the split I weighed on top of the blower shield
I will weight them now & then to see how much, if any moisture reduction i get.
With the blower running at any temp, the shield is not hot, cooler than the stove pipe.

 

Measured how - single wall magnetic thermometer, double wall probe?

 

No idea ? ?
Reference from this brochure:
http://www.blazeking.com/PDF/brochures/en/current/wood/83651_BK_King_Prin_Brch_Final.pdf

"
Burn 33% less wood The combination of our exclusive thermostat and catalytic combustor technology
makes your Blaze King stove one of the most efficient wood stoves in the world. The proof of this is in our
flue temperatures. Non Blaze King stoves have flue temperatures of between 600°∆ F and 900°∆ F while your
Blaze King flue temperatures are between 150°∆ F and 300°∆ F. Non Blaze King stoves pump valuable heat up the flue.
Your Blaze King catalytic stove keeps the heat in your home saving you money. By making your stove this efficient you will
burn up to 33% less wood, cut, stack, load and clean 33% less wood. This is a major advantage that only a Blaze King offers."

I had to go to 200% on the online pdf brochure to see the burn chart & verbage

Bottom dark line is their exhaust temps thru the 48 hour burn cycle, wavy blue cat temp. steady darker blu is fuel level, 54 lb load of Tamarack

 

Pretty impressive to me for the exhausts temps to be so low.
Efficient wood stoves, heat goes in the house not up the stack .

Good dry wood is a lot of the efficiency factor
The new efficient stoves won't operate efficiently with out dry wood.
(really no stove will , the new ones are more sensitive, the "need" dry wood)

 

Woodstock did a pretty impressive test using green cordwood with the Progress Hybrid:
http://blog.woodstove.com/2012/01/catalytic-combustors-wet-wood.html?m=0

 

Cool moisture meter
No splitting to measure % moisture

Now if I could put my stove on an accurate scale to measure the fuel usage like that.
36% moisture maple
.2 lbs per 5 minutes, that's a pretty slow burn.

20%
Similar dirty glass on the edges for the low setting that I get.
Much better burn.

Seems catalytic's are better all around.

Need a good tight flue, with low temp burns.
Leaks can cause a loss of the draft. That I learned the hard way
Glad I had CO alarms !

 

The 30 is at 450 right now. Single wall pipe is at 189.

When the 30 is cranking at 650-750, but settled in with the air closed down, Pipe is in the 250 range. I'll measure again when I reload in an hour.

 

PH is at 450 stove top and flue gases at 550... Most of the time I find my flue gas temps match my stove top temps..

 

Did you use any specific method to locate the leaks?

 

I used a butane lighter.
Could see the flame pull into the leak.
A candle works.
A smoking stick would work, like inscense , cigar, cigarette

Get the flue good & hot. Then go
around the joints.

 

My PH almost always ran cooler on the flue probe than on the stovetop. Max I ever got on the probe was 600 and that was rare, mid-burn in the 450 range on flue probe, not unusual for probe to drop below 400 while stovetop just starting to drop from 500.

But nothing like laying a bare hand on the pipe. Nice to keep that heat in the house.

 

On catalytic stoves;
I think exhaust temp would be a great indicator for the
condition of the cat combustor.
As the temp goes up with the same settings/ conditions
the efficiency of it is dropping off.

Sound logical ?

 

I don't monitor my flue temps much anymore, mostly cat temps and stove top. My exterior single wall temps 12" above the flue collar cruise around 300-400 depending on the air setting. My old BK Princess burned about 100 degrees cooler flue temps.

I think the BK low flue temps have a lot ot do with that heat shield that is located directly behind the cat and in front of the flue collar which cuts off or slows down that exhaust and keeps that heat in the stove. My Woodstock has a heat shield as well but it doesn't block off the flue collar, it's more directed towards the stove top. Maybe that heat shield is the real reason the stove is so efficient? Just a simple piece of metal redirecting the heat to stay put in the stove.

 

I see about the same for mid-burn, maybe 500 for a few hours... Same thing here on the max pipe temp, I think I saw that once when the cat was really cooking, draft closed 100% with the stove top at 650... Looked closer at my wood I had filled the box with... pig nut hickory! Look out! I still want to install a pipe damper sometime... If it doesn't do any good then I'll just leave it open, but,,,, if it was needed I'll have made a very good move... I seem to have a really good draft with double wall inside coming out of the top of the PH , into a 90, then a foot to the wall and into an insulated liner that goes up a 22 foot masonry chimney.. I would thing with the 90 and the tee in the chimney I would not have an overdraft , but I could be wrong... The PH never once smoked out the loading door and the same with the Fireview... Maybe that 22 ft run is really pulling some heat.

 

Makes sense. Never thought about that. I thought it was only there to make cleaning more difficult.

I had almost 750 on the top the other night, and I could touch the double wall pipe and count to three, though I had to count really fast.

Glad to see you could make it.

 

Yeah, maybe it's not alien technology? I've been thinking about this all morning and I wonder if anyone has tried rigging some kind of shielding like this to redirect flues gases and keep less heat from going up the stack. Really wouldn't be that hard to do in any stove but there's a chance of overfiring if you don't have good control.

 

I'd rather have a warmer flue then any question of what might be building up running things too cool... I guess that all my wood comes from my property that I'm not worried about how much I burn.... I can say when I had a gasification wood boiler, the big thing was to extract every bit of heat from the super hot flame in the secondary chamber and not let it go up the pipe , keeping internal flue gas temps at 300 degrees tops... Well this eventually resulted in a chimney cap fire which fortunately was in an outside building with a metal roof as flaming pieces of creosote came raining down... So for me after personally seeing this happen I don't mind a flue temp of at least 400....

When we are talking single wall surface temps readings of 250 , are we in agreement that with a flue probe we would be seeing 500 degrees?

 

Same this AM
Laid my hand on the pipe for 10 seconds,
Gotta be near 150 or less
Stove still cranking, -3 OAT, house 73°

To me that's impressive even having double wall pipe.
Heat in the house not up the stack