Soapstone stoves take longer times to heat up???

[Heat Miser]

Great info / feedback - thanks!! I point my IR therm at the flue (single-wall pipe out the back to the stainless tee, then immediately into the 6" SS flex) and generally the temp reading on the pipe matches the top-center stone temp +/- 25F. Going from a 280-320 surface reading up to ~850 internal flue temp sounds like it'll be... interesting.

My flue temp right now is about 400 degrees which I consider a good low-burn range. The flue never gets up to 850 unless I'm really trying to get the fire hot.

Oh btw - I meant those pre-packaged hardware/grocery store firewood bundles - not burning 2x4's ;-)

Ahh! Ok well that would work, but they are expensive!

Gonna pick up a box of those Enviro-Logs (i think that's what they were) from the hardware store, and see how a few of them light off. Then try to find the time to build the big honkin' woodshed...

Make sure they are true compressed wood logs with no binders. Not the duraflame/wax log stuff.

The compressed wood logs are easy to use. I use a small hatchet to chop them into small disks like a roll of cookie doug for "kindling". Then I'll just feed in full logs to get the fire really going. I would never burn more than three at a time though as they get very hot and expand quite a bit once they start burning.

 

[jpl1nh]

I have a couple of other points regarding the reduced temperature swings and longer heat output with soapstone stoves. These stoves are primarily radiant heaters. They warm objects as much as the air. Therefore, to an extent, the obejects in your room also become thermal mass and radiate heat too. With the great heat holding capability of soapstone, the firebox does stay warm longer which seems to help hold coals much longer and truly burns wood completely. All we ever empty from our Keystone is fine ash, no cinders and colas as olong as 18 hours after a stove full hardwood fire are not unusual. Someone asked about the heat going up the chimney, but when we are well into charing a load of wood, we reduce the airflow so low that there is not a whole lot of air going up the chimeny, and I would imagine that flow further decrease as the stove cools and the inside outside temp differential decreases. Risser, as the temps start to drop outside, you'll find it easier to get your stove top temps up on your Keystone. One way to do it now is to get your stove up to temp and let the load burn down about half way. You should be at around 450 temp at that point and about halfway to coal stage. Refill your stove to the top again. Within 3 or 4 minutes you'll be able to engage the combustor again but keep the air a bit more open for a few minutes longer. Then slowly start shutting your air back down in 2 or 3 small steps being careful not to go so far as to extinquish the flame. Your cat should start crankin from all the new fuel gassifying in the presence of an already hot firebox and 600 to 650 is likely. You should (depending on wood type) be able to hold that for an hour or two before you slowly cool down from there.

 

[Risser09]

I will certainly try that. I have not been dropping the airflow in stages as you recommend, although I still get ghostly flames around 1. Woodstock says you can successfully run your cat from 0-2. Thanks for the advice! I will report back here tomorrow.

 

[Kansasplains]

All right! Another Woodstock owner chimes in. This post sure is bringing all the soapstone/cat owners out of the woodwork.

This is our first season with our Keystone and we absolutely love it. It is our main heat source with backup central heat, but so far we haven't spent a dime on propane this fall. Now that's a good feeling.

it seems to me that heat stored in the stove mass (e.g. a soapstone slab attached to the stove body) is more wasted than a thermal mass NOT attached to the stove. it is more wasted because it is also radiating to the inside of the stove, and therefore to the flue and being exhausted to the outside.

I don't think much radiant heat goes up the chimney. The heat going up the chimney is from convection. I put several small pieces in after work tonight and took it up to cat temp. Right now 1 1/2 hours later the stovetop thermometer is showing 450 and my magnetic flue thermometer is at 140. So even after the fire goes out and the flue cools way down, that soapstone still keeps on putting out the heat. If I remember right, radiant heat can only travel in a straight line until it is stopped by something. Here's an actual example of this. Our hardwood floors have usually been fairly cold. With our soapstone, the floors stay very nice and warm. The other night I moved a pillow that was lying on the floor and was amazed at how cold it felt where the pillow had been. Around it the floor was warm, but underneath it was cool.

I agree with Heat Miser that a soapstone stove should also have a flue thermometer. When I'm trying to get up to high heat output fast, I watch my flue temps. Here's my understanding of the 250 degree cat engage point. Because the soapstone holds so much heat, the stovetop temp is usually about half the flue temp when the cat is not engaged. The flue gas should be somewhere around 500 degrees for the cat to engage, hence the 250 degree stovetop reading. By watching flue temps, I can easily see when the 450-500 degree point is reached, even though the stovetop may only be at 175 to 200 degrees. By engaging the cat, backing the draft down to around 2 and letting it burn for about 5 more minutes, the stovetop temps go up pretty fast. That's when I slowly throttle it down to the famous 1/2 setting, sit back and enjoy.

My wife was very hesitant to have a wood stove in the house. She grew up with an old smoke dragon at their house which made the house smell slightly smoky and deposited a very fine layer of black dust over everything in the house. She remembers having to dust the house every several days just to get rid of this dust. But, she finally agreed to get a stove. For starters, she absolutely loves the look of the Keystone. And now, she is totally sold on the awesome heat that this thing puts out. And just today a friend stopped in and was commenting on how she smelled absolutely no smoke in the house.

Happy heating.
Brian

 

[Backwoods Savage]

I have a couple of other points regarding the reduced temperature swings and longer heat output with soapstone stoves. These stoves are primarily radiant heaters. They warm objects as much as the air. Therefore, to an extent, the obejects in your room also become thermal mass and radiate heat too. With the great heat holding capability of soapstone, the firebox does stay warm longer which seems to help hold coals much longer and truly burns wood completely. All we ever empty from our Keystone is fine ash, no cinders and colas as olong as 18 hours after a stove full hardwood fire are not unusual. Someone asked about the heat going up the chimney, but when we are well into charing a load of wood, we reduce the airflow so low that there is not a whole lot of air going up the chimeny, and I would imagine that flow further decrease as the stove cools and the inside outside temp differential decreases. Risser, as the temps start to drop outside, you'll find it easier to get your stove top temps up on your Keystone. One way to do it now is to get your stove up to temp and let the load burn down about half way. You should be at around 450 temp at that point and about halfway to coal stage. Refill your stove to the top again. Within 3 or 4 minutes you'll be able to engage the combustor again but keep the air a bit more open for a few minutes longer. Then slowly start shutting your air back down in 2 or 3 small steps being careful not to go so far as to extinquish the flame. Your cat should start crankin from all the new fuel gassifying in the presence of an already hot firebox and 600 to 650 is likely. You should (depending on wood type) be able to hold that for an hour or two before you slowly cool down from there.

Good post but I'll caution on two things:

While I certainly agree that you need to cut back the draft so that all the heat doesn't go up the chimney, you can also cut it back too soon. Just be cautious on this.

I don't think I would ever engage the cat in 3-4 minutes no matter what wood is added! I say 10 minutes minimum, even with well seasoned wood. The wood we are burning at present is 3-4 years old (stacked and split that long) and we still go a minimum of 10 minutes and sometimes longer. Also, we start the timing by when the flames start; that is, sometimes when you add wood it is a couple minutes before you get flames. That is when to start the timing.

 

[Backwoods Savage]

All right! Another Woodstock owner chimes in. This post sure is bringing all the soapstone/cat owners out of the woodwork.

This is our first season with our Keystone and we absolutely love it. It is our main heat source with backup central heat, but so far we haven't spent a dime on propane this fall. Now that's a good feeling.

it seems to me that heat stored in the stove mass (e.g. a soapstone slab attached to the stove body) is more wasted than a thermal mass NOT attached to the stove. it is more wasted because it is also radiating to the inside of the stove, and therefore to the flue and being exhausted to the outside.

I agree with Heat Miser that a soapstone stove should also have a flue thermometer. When I'm trying to get up to high heat output fast, I watch my flue temps. Here's my understanding of the 250 degree cat engage point. Because the soapstone holds so much heat, the stovetop temp is usually about half the flue temp when the cat is not engaged. The flue gas should be somewhere around 500 degrees for the cat to engage, hence the 250 degree stovetop reading. By watching flue temps, I can easily see when the 450-500 degree point is reached, even though the stovetop may only be at 175 to 200 degrees. By engaging the cat, backing the draft down to around 2 and letting it burn for about 5 more minutes, the stovetop temps go up pretty fast. That's when I slowly throttle it down to the famous 1/2 setting, sit back and enjoy.
Happy heating.
Brian

On the flue temperature. It certainly makes a difference how that temperature is taken as does how the pipe runs. For example, our pipe runs horizontally rather than vertically from the stove. Therefore we'll get hotter readings sooner.

On the temperature for engaging the cat., it does depend upon stove temperature and not flue temperature. We've found no correlation between the flue temperature and stove top temperature as to when we engage the cat. We've had flue temperature of 600 degrees or higher before engaging the cat. and also have had flue temperature of less than 500 degrees, but never less than 250 on the stove top.

We always go by the stove top temperature as stated by Woodstock, which is approximately 1/2 the temperature of the interior of the stove. We also never let the wood burn less than 10 minutes before engaging the cat., no matter how hot the stove or flue. We do this even though our wood has been split, stacked and covered for a minimum of 3 years; some longer.

 

[Kansasplains]

We always go by the stove top temperature as stated by Woodstock, which is approximately 1/2 the temperature of the interior of the stove.

I think I got a little mixed up in my post. I should have said that the stove top is 1/2 the interior temp, not flue temp. Thanks for the correction, Backwoods.