Woodstock and other Cat users - Max heat output survey

My Classic doesn't get really hot until the cat is engaged and it has burned some of the load - probably a good part of this is that I have a stove top thermometer. But - I can easily overfire if I load it up at 450 on the stovetop and leave the damper wide open. As for the question, I find it gets hottest with a bit of flame - but not roaring.

I know what you mean. Sometimes in my stove if I reload on a large coal bed and turn the air way down til the coals red glow goes away, the cat seems to hit that feeding frenzy with the smoke and the stove top climbs rapidly up to 700 if you let it. Maybe the cat is doing all the work from a lack of red coals and flames in the firebox?

If you give it too much air the smoke and gas don't have enough time to ignite the cat and you end up wasting fuel up the flue. You can see this by monitoring your flue temps. I like to keep mine below 325 (external) and they usually are below 300.

When it's this cold outside I go for a 7-8 hr burn and try and keep red coals with a good amount of flame going. The air setting is usually around .75 or a bit more, and stove temps of 500-650. This seems to give more heat than my lowest air long burn sweet spot even though the stove top temps could be the same with a lower setting. I think more heat in the lower mass of the stove? One of the IR thermometers would be a good tool to see what overall stove temps could be between different air settings.

I don't own the woodstock but am interested in knowing, can you just shut the air to zero after the cat is engaged and keep the cat going or will everything get "snuffed"? Seems that since the cat is at the very top of the stove right near the flue that the hot cat will have a hard time heating the lower half of the firebox so a mix of a decent coal bed and an ignited cat would give more heat than a cat alone.

Highbeam said:

I don't own the woodstock but am interested in knowing, can you just shut the air to zero after the cat is engaged and keep the cat going or will everything get "snuffed"? Seems that since the cat is at the very top of the stove right near the flue that the hot cat will have a hard time heating the lower half of the firebox so a mix of a decent coal bed and an ignited cat would give more heat than a cat alone.

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The only time I've shut the draft off is when there was a bit too much flame for my comfort and the stove top got over 650 degrees. However, we do run at .25 a lot of the time.

I have noticed that if I burn all maple, then is when the temperature soars, but when we fill the firebox for overnight, we usually only burn one maple but sometimes two and fill the rest with ash, cherry or oak and perhaps some elm on occasion. At present, we are burning mostly ash though because we have so many trees dying.

Last night with one maple and the rest ash, it took a very short time for the stove top to reach 550-600 and I went to bed. I got up sometime in the night and the temperature was 525 with still plenty in the firebox.

Also, the cat is at the top of the stove, but not right near the flue. The cat is at the front of the stove and the flue is out the back. Also, the cat does not heat the lower half of the firebox. Heat goes up around here but might be different in various places.



Back to the original question, I feel that the flame you get with it dancing at the top of the glass and red cat gives maximum heat. That flame is pretty to watch too.

Highbeam said:

I don't own the woodstock but am interested in knowing, can you just shut the air to zero after the cat is engaged and keep the cat going or will everything get "snuffed"? Seems that since the cat is at the very top of the stove right near the flue that the hot cat will have a hard time heating the lower half of the firebox so a mix of a decent coal bed and an ignited cat would give more heat than a cat alone.

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I think if you shut her down completely and you can, there is no air supply stop, it will snuff out because the cat also needs some air to combust the smoke. There must be a fine line there somewhere.

On the contrary Todd, we have shut off the air several times and the fire (and the cat) just continues to go merrily along just fine for a long time.

Backwoods Savage said:

On the contrary Todd, we have shut off the air several times and the fire (and the cat) just continues to go merrily along just fine for a long time.

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Well, then this stove isn't as air tight as they say. I'd try it but when I turn it down below .5 I get some smoke smell.

Well, then this stove isn’t as air tight as they say. I’d try it but when I turn it down below .5 I get some smoke smell.

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I think the newer EPA stoves are designed to have at least a minimum air intake even when the inlet is closed all the way. At least that's what I vaguely remember reading. This may be for reducing creosote. It may be air tight every where else (firebox, door, etc...).

I may be wrong.

Mike

Well, what about sticking a thermometer on the side door? I have an extra thermometer maybe I'll do some experimenting.

For my FV setup anything below 1/2 on the air is marginal as far as keeping the cat lit. I think the stove actually runs hottest with a fresh load and moderate (like 1 to 1.5 ) air. The best efficiency is at the lowest burn possible to keep the cat going. A thermostatic system for air would be interesting. A flue heat exchanger might also work very well for those times when more heat is needed; as the cat should reduce the risk of creosote to a minimum - and you'd get back at least some of the heat that would otherwise go up the flue. You'd want to turn it off during a long burn as the stack temps are already very low. Anyone using a Magic Heat or equivalent on a Woodstock?

Since starting burning 30 days ago I've used not quite all of single row off my woodpile; 16" splits x 5 1/2 feet long x 7 ft tall --- about 47 cu ft. or less than 1/2 cord. This keeping 1200 sq ft of ranch home very comfortable.

Todd said:

Well, what about sticking a thermometer on the side door? I have an extra thermometer maybe I'll do some experimenting.

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Ok, this what I came up with after reloading my stove tonight.
Stove top and Lower door temps
reload 250 300
engaged cat 290 640
#1 after 1/2 hr 500 500
#.5 after 1hr 550 400

Definitely a difference in lower firebox temps after engaging the cat. The door temp really shot up fast in the bypass mode and dropped after engaging. If I would of left it at #1 I'm sure the stove top temp would of continued to climb, but I need a long overnight burn so I turned it down after 1/2 hr. So it makes sense to me if you want more heat from this stove don't be fooled by high stove top temps as the only way to figure heat output. Keep some red in those coals and give it some more air to heat up that lower soapstone mass if you need more heat.

rickw said:

For my FV setup anything below 1/2 on the air is marginal as far as keeping the cat lit. I think the stove actually runs hottest with a fresh load and moderate (like 1 to 1.5 ) air. The best efficiency is at the lowest burn possible to keep the cat going. A thermostatic system for air would be interesting. A flue heat exchanger might also work very well for those times when more heat is needed; as the cat should reduce the risk of creosote to a minimum - and you'd get back at least some of the heat that would otherwise go up the flue. You'd want to turn it off during a long burn as the stack temps are already very low. Anyone using a Magic Heat or equivalent on a Woodstock?

Since starting burning 30 days ago I've used not quite all of single row off my woodpile; 16" splits x 5 1/2 feet long x 7 ft tall --- about 47 cu ft. or less than 1/2 cord. This keeping 1200 sq ft of ranch home very comfortable.

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A thermostatic system like they have on the Blaze King and VC's would be awsome for this stove and I bet it wouldn't be too hard to rig one.

I don't trust the Magic Heat. I had them on other stoves and they just produced creosote and were noisy.

The most heat I have found is after a reload on a thick hot coal bed. Wait about 5 min then damper down until the only flames are the gasification flames dancing at the top of the burn box. I set around 2.5 on my blaze king classic normally and 3-3.5 if it is colder than -35. I get 14 hrs on 2.5 and 8-9 on 3.5. This is my economy burn plan. On a cold morning when a 75 - 80 degree living room sounds nice I run wide open (cat engaged) with spruce for about 1 hr. This cleans the glass and stove to spotless. I only load 1/4 full for my fast hot burns and the wood only lasts about 2 hrs. My normal wood is seasoned birch.

[quote author="Todd" date="1231926824[/quote]

A thermostatic system like they have on the Blaze King and VC's would be awsome for this stove and I bet it wouldn't be too hard to rig one.

I don't trust the Magic Heat. I had them on other stoves and they just produced creosote and were noisy.[/quote]

The thermostatic control is nice. From a full roar and then a complete turn down so there is no flames and barely a any glowing coals the stove temps above the glowing cat will climb. After 2-3 hours the temps will drop from 750f down to 400 to 350f. Cat is no longer glowing.
At around 350 you will notice the ashes in the stove to start swirling and the load of wood at the outer edges start to glow again.
The wood will not break into a flame but you will notice more smoke start to swirl in the fire box. The cat may begin to have a real dull glow, if the lights are out you will notice it. Temp will climb to 450f or so and level out again at 350f. This will produce a good long burn. Great for milder temps. Minus 12c or warmer. Stat setting is at #1.5. A setting of #1 temps will peak at 300 with no glow.
Never smoke out the chimney. I find with the stat turned up on high, Cat will glow and flames will roll nicely. Alot of extra heat from the glass front. When the stove is on low most of the heat is from the stove top. On high burns I think for the first part of the burn I will get trace smoke out the stack. To me thats waisting fuel. Burn times go down to 6hrs or less. I will rarely run the stove above mid setting to stay away from the trace smoke. Mid way through the burn when Iam at home and its severely cold I will then set the stat on high/#3. Stove will settle in at 650 700f stove top for the remainder of the burn with no smoke and a good heat gain with the fans on. With the thermostatic contol I will allways pack the stove as tight as I can as it will not effect the heat output overall other than the length of burn times for reloading. This is done 95% with spruce and pine. Spruce will shorten my burn times as much as 2hrs.

This morning I reloaded with full load of Black Locust and 1 stick of Elm, got her going good for 15 minutes and engaged at #1. 2 hours later stove top at 625, side door is holding at 550, and external stack temp 325. Red hot coals and plenty of flames, no smoke, just steady stream of white steam that vaporizes 2' from the cap. I can get the same stove top temps with a lower setting but the side door temp drops down to 400 or so.

I'd like to see one of those Blaze Kings in action with a full load of hardwood. There is a place about an hour from here that sells them, One of these days I'm going to go take a look. I wish Woodstock would come up with a theromastic control add on.