Maximum Heat - What's Your Technique?

[leeave96]

The temperatures have plunged again this weekend and I have been playing around with my woodstove to figure how to safely max the heat output while balancing the stove/stove top temperatures and the stove pipe temperatures.

I have a stove top thermometer and a stove pipe thermeter - both magnetic surface types.

My manual says 700 degrees is the max stove top temp and I have used my stove enough now to know the sound and smell of the stove pipe and what that temperature reading shoud be to be just below it.

So what I've tried tonight is to play around with my damper settings with the goal of safely maxing the heat output of the stove - without sending to much heat up the chimney.

With my set-up, I have a horizontal double wall stove pipe that goes straight into my chimney liner. My thermometer is near the stove outlet and on the top of the pipe. What I have learned is that when it hits 250 degrees, I am close to smell and popping expansion sounds. So as the stove nears 250 degrees on the pipe I start dampering down. When I cut the damper back in small increments, the stove top and stove in general puts out more heat as less of it is going up the chimney. With the pipe at 250 degrees, I've got plenty of flames in the stove vs a smoldering fire. The cat is glowing bright orange and the stove temp continue to climb. There comes a point where if I continue to damper down, I start to slow down the fire vs moving the heat from going out the chimney to the keeping it in the box.

Tonight, with some maple (I've got some oak and locust waiting in the wings), I was able to hit my 250 stove pipe limit and bring the stove top up to about 675 degrees. At this point, I had worked the damper setting such that the stove was able to cruise at these temps for a couple of hours before the wood was started going to charcoal and the stove and pipe temps starting to fall off. I still was able to keep things above 500 for another couple of hours. Most likely these temperatures towards of the end of the high temp burn were driven by heat stored and being released by the soapstone.

To keep the living room from exceeding 80 degrees, we opened more interior doors to rooms that we might have otherwise closed.

Pretty impressive how these stoves can throw off a ton of heat and burn it clean too.

What is your safe - maximum heat output technique?

Thanks!
Bill

 

[HotCoals]

If you can hit 675 stove top and only 250 on the stack you're doing great!
I just reread and see you have double wall pipe..so your stack temp is actually a lot higher then 250.
Still I figure you're doing good.
My stove cruises at around 350-400 stove top near cat and 200-250 8 inches up the single wall pipe.
I have had no reason yet to turn it into a blast furnace..lol.

 

[Backwoods Savage]

Bill, I think you know we have the Fireview. Most of the time the high temperature is reached only if we really load the stove up but we rarely do that during the daylight hours as we usually only put in 3 or 4 small splits then. But sometimes even with a light load of wood the stove top will go over 600; most of the time 500 with only a light load. If the temperature goes way up on the light load, it does not stay there very long before dropping.

If we really want heat we will load the thing up and when we engage the cat the stove top temperature will really go up towards the 700 mark. The draft setting we use is mostly about .75 but sometimes higher and other times lower. We do try to keep some flames in the firebox but many times during the night I will come out to find no flames, yet the stove top temperature will be anywhere from 550-650. Still, most of the time we will have a small flame; we do not want a lot of flame for sure as that could possibly have negative effect on the cat. But when we get that stove temperature up to 600 degrees, it can roast us out if it stays there long.

 

[leeave96]

Bill, I think you know we have the Fireview. Most of the time the high temperature is reached only if we really load the stove up but we rarely do that during the daylight hours as we usually only put in 3 or 4 small splits then. But sometimes even with a light load of wood the stove top will go over 600; most of the time 500 with only a light load. If the temperature goes way up on the light load, it does not stay there very long before dropping.

If we really want heat we will load the thing up and when we engage the cat the stove top temperature will really go up towards the 700 mark. The draft setting we use is mostly about .75 but sometimes higher and other times lower. We do try to keep some flames in the firebox but many times during the night I will come out to find no flames, yet the stove top temperature will be anywhere from 550-650. Still, most of the time we will have a small flame; we do not want a lot of flame for sure as that could possibly have negative effect on the cat. But when we get that stove temperature up to 600 degrees, it can roast us out if it stays there long.

Dennis,

With my much improved draft with the new liner and rear horizontal stove pipe exit into it, I am using much less damper to get hot stove top temps. If I go with a no flame fire and glowing cat, I can drop it as much as 1/2 and have gone down to 1/4. When the outdoor air temps get much warmer, I think I could go to zero without totally smothering the fire as I re-opened the small hole in my ash pan housing - so there is always some air coming into the firebox.

Most of the time we are at 1 or 1-1/4 as when outside air plunges, we want more than stove top heat and flames really get the sides throwing off heat. If I want a quick char of the new loads, I will put the damper at 4 for a few minutes (I never leave the door open to do this) and then down to 2. Even at 2, and in bypass, the flames engulf the wood pretty quickly. I go down to 1.5, engage the cat and I'm making good heat. What I was playing with last night was a balance between stove top temps and stove pipe temps to see where my stove will max out it's heat output. It's amazing to me that a stove with such a small firebox, 1.4ish cu-ft, can make so much heat and keep it for so long. What kind of stove pipe temps are you seeing at 650ish stove top temps and the damper at .75?

My cat is pretty much buried behind an expanded metal screen and a heat shield. I don't think the flames are hitting the cat or getting sucked-into it, but it will be interesting to see how the cat fares after a hard 24/7 season of burning. So far, the cat lights-off and burns pretty much like it did when new - fingers crossed.

Thanks!
Bill

 

[Backwoods Savage]

Bill, I also find it amazing how small the Fireview is but it surely gives off a lot of heat. It is the smallest stove we've ever owned but is also the best one we've ever owned.

Full draft is also what we do on reloads. On reloads we really watch the flue temperature and at 500 we engage the cat. I do not always go this route though as I watch the actual fire to base most of my decisions on. When engaging the cat I'll usually drop the draft to about 1.5, depending on the fire. If a real hot fire I'll go right to .75 or 1.

Our stove pipe temperature usually will be over 350-375 when we are at 650 stove top. Generally the pipe temperature is around 350 but by the time we reload it will be down to 300 or sometimes below that. The only time it runs hot is with full draft on the reloads. As soon as we engage the cat and drop the draft back the flue temperature will slowly back down to around that 350 mark.

 

[Battenkiller]

Bill, I also find it amazing how small the Fireview is but it surely gives off a lot of heat. It is the smallest stove we've ever owned but is also the best one we've ever owned.

That stove is a perfect match for your size home. It would do the job wonderfully for me as well if only I had a place to put a stove upstairs. Only conceivable place is in the existing fireplace, but all the cat stoves I've seen are way too big to fit. But I really do envy you guys, though. You have the most effective technology available today AFAIC, and your well-seasoned fuel is custom made for such a stove. Win-win in your situation.

 

[Todd]

I haven't really needed to push my Keystone since the Fireview has most of the load but I too find the pipe temps a valuable tool as far as heat output goes. My Keystone has single wall 45 off the top and I place the thermometer about 6" up. What I have found is generally a hotter fire with more flames the pipe temp will be around 450 and when I turn it down to a low slow burn it drops down to 350. The same thing goes for my Fireview but my pipe thermometer is higher up and I get 250-350. There is a fine line there somewhere between efficiency and too much heat up the stack. Woodstock has told me the most efficient fire is where the flames start to slow down and lift off the logs. For me this is about .75 on the Fireview and #1 on the Keystone. This should give you the most heat in the longest period but it doesn't mean it's the most practical for everyones situation. Sometimes you just need more heat and you have to open the air to get the whole stove hot. It may hurt burn times and efficiency but don't be afraid to open her up.

Now there is another whole story when it comes to stove top temps. It's kind a weird seeing a stove top temp at 700 with no flame in the box but that is just how cat stoves are set up. Since the cat is right under the top you can get what I call smoke overload where the cat makes all the heat while the rest of the stove is relatively cooler. Turn up the air, get some flame and the temp drops on top and increases around the sides. I find I like to keep some flame or at least red coals in the fire box just to keep some of the pressure off the cat and I also get more consistant stove top temps along with pipe temps.

 

[Backwoods Savage]

Bill, I also find it amazing how small the Fireview is but it surely gives off a lot of heat. It is the smallest stove we've ever owned but is also the best one we've ever owned.

That stove is a perfect match for your size home. It would do the job wonderfully for me as well if only I had a place to put a stove upstairs. Only conceivable place is in the existing fireplace, but all the cat stoves I've seen are way too big to fit. But I really do envy you guys, though. You have the most effective technology available today AFAIC, and your well-seasoned fuel is custom made for such a stove. Win-win in your situation.

Thanks Battenkiller. That was a nice post.