Understanding Keystone Burn Times

Status
Not open for further replies.

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
I'm trying to get a handle on understanding burn times. I was under the impression that if a stove claims a burn time of 8-10 hours I could walk away from the stove for 8-10 hours and get approximately the same amount of heat from it over that time period. (or course temperatures are going to decrease, but slow and steady over time)

I'm working with a catalytic stove that I babysit every couple of hours. An analysis of my burn times are as follows.

After slowly warming up the stove to catalytic temperatures (300F stove top temp) I load the stove full of 16-18" seasoned oak hardwood.

Hour 1 - The stove top temperature reaches 600 degrees.
Hour 2 - The wood has pretty much burned up. It retains its original shape but I can break it apart into large chunks of burning coals. Stove top temperatures are around 500-550F
Hour 2.5 - Coals still glowing hot but temperature is falling and it is at this time I disengage the catalytic, open the draft and add more wood. I wait until the wood is burning well, partially close the draft and re-engage the catalytic.

So, if asked I'd say I'm getting 2.5 - 3 hours of burn time.

If a stove is rated at 8-10 hours, what is happening in the firebox at hour 4? Hour 5? Hour 8??
How will stove top temperatures change over the course of 8-10 hours?

Thanks, guys
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,115
South Puget Sound, WA
Burn times are essentially a marketing tool. To a sales person burn time means the time from lighting the stove to the time the final ember goes out. Some stove companies, like Blaze King are a bit more honest about burn times, but not many. Most stoves produce heat in a ski slope curve. The temp goes up rapidly (the ski lift) and then declines gradually (the slope). A more meaningful metric is the period of meaningful heat. That would be the time between say a 300F stove top on the way up and back to 300F on the way down the slope.

What stove is this? Can you add it to your signature?
 
  • Like
Reactions: radtechrad

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
Burn times are essentially a marketing tool. To a sales person burn time means the time from lighting the stove to the time the final ember goes out. Some stove companies, like Blaze King are a bit more honest about burn times, but not many. Most stoves produce heat in a ski slope curve. The temp goes up rapidly and then declines gradually. A more meaningful metric is the period of meaningful heat. That would be the time between say a 300F stove top on the way up and the way down the slope.

What stove is this? Can you add it to your signature?

We just moved into a 1300 sqft home with a Woodstock Keystone Catalytic stove. The previous owner overfired the stove and didn't take care of it. I'm addressing issues with the stove and chimney. So, I'm not burning wood under ideal conditions. Having said that, I just wanted some clarification regarding burn times and what to expect. Now that I know it is a marketing tool.....well, that figures. <>
Thanks for the reply, Begreen!
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,115
South Puget Sound, WA
There are several Keystone owners here that can give you some real world info on their burn times. I'm going to add Keystone to the title for greater visibility. Most are reporting greater times, but it could be you are pushing the stove harder or it has something wrong. The Keystone by all reports is a good stove and should be up to the job. How is the house insulation and sealing?
 
  • Like
Reactions: radtechrad

danimal1968

Member
Feb 3, 2014
98
Pickerington, OH
We just moved into a 1300 sqft home with a Woodstock Keystone Catalytic stove. The previous owner overfired the stove and didn't take care of it. I'm addressing issues with the stove and chimney. So, I'm not burning wood under ideal conditions. Having said that, I just wanted some clarification regarding burn times and what to expect. Now that I know it is a marketing tool.....well, that figures. <>
Thanks for the reply, Begreen!
I think most folks who have Woodstocks will tell you that their advertised burn times are in line with what Woodstock advertises. There are numerous folks on here who own Keystones who will tell you that something is very wrong if you're only getting 2-3 hours of usable heat out of yours.

Woodstock has excellent customer service; I'd definitely give them a call.

When you say your oak is seasoned, how long has it been seasoned and what's the moisture content?
 

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
There are several Keystone owners here that can give you some real world info on their burn times. I'm going to add Keystone to the title for greater visibility. Most are reporting greater times, but it could be you are pushing the stove harder or it has something wrong. The Keystone by all reports is a good stove and should be up to the job. How is the house insulation and sealing?
It's a manufactured log home with drafty windows. We've owned it for 6 months and I couldn't address all the issues needed to make it ready for winter. Here in PA we had -2F a few days ago. Today we're at 18F. It's also quite windy here. Thanks for adding Keystone to the title. I know it's a gem of a stove, but it's suffered at the hands of someone that didn't know how to use it or care for it. I think I may be paying for his misuse of the stove with short burn times.
 
  • Like
Reactions: Tenn Dave

begreen

Mooderator
Staff member
Nov 18, 2005
79,115
South Puget Sound, WA
It is not untypical for burn times to go down as the stove is pushed harder. Lots of folks are seeing this with those cold temps and strong winds. In more normal winter temps in the 20s I think you will see 8hr burn times. It's like gas mileage. Your car may get 30mpg by EPA testing, but will see only 20mpg if driven at 80mph into a strong headwind.

I would get some heat shrink window film up. It works very well.
 

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
I think most folks who have Woodstocks will tell you that their advertised burn times are in line with what Woodstock advertises. There are numerous folks on here who own Keystones who will tell you that something is very wrong if you're only getting 2-3 hours of usable heat out of yours.

Woodstock has excellent customer service; I'd definitely give them a call.

When you say your oak is seasoned, how long has it been seasoned and what's the moisture content?

I have a General moisture meter I picked up at Harbor Freight. The moisture content of the wood I've been burning registers 0 - 4.5%. It's been drying for approx 18 months.
 

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
It is not untypical for burn times to go down as the stove is pushed harder. Lots of folks are seeing this with those cold temps and strong winds. In more normal winter temps in the 20s I think you will see 8hr burn times. It's like gas mileage. Your car may get 30mpg by EPA testing, but will see only 20mpg if driven at 80mph into a strong headwind.

I would get some heat shrink window film up. It works very well.
I do agree, the windows are a big issue. But, so is the rest of the house! LOL. The window film would definitely be worth spending a weekend installing. Thanks!
 

begreen

Mooderator
Staff member
Nov 18, 2005
79,115
South Puget Sound, WA
I have a General moisture meter I picked up at Harbor Freight. The moisture content of the wood I've been burning registers 0 - 4.5%. It's been drying for approx 18 months.
Something is not being read correctly or the meter is whacked. Super dry, unfinsihed flooring wood is 8%. Normal cordwood is 15-20% when nicely seasoned. Are you testing on a freshly split face of the wood (not endgrain)? Are you pressing the probes firmly into the wood grain?
 
  • Like
Reactions: radtechrad

TheRambler

Feeling the Heat
Jul 29, 2014
478
CT
Either your meter is broken ot you arbt measureibg a fresh split face. No way wood will ever read less than 5%.

Also, how old is the cat in your keystone? If its older than 5+ years that could be pary of the problem. Have you cleaned and inspected the cat?
 
  • Like
Reactions: radtechrad

Highbeam

Minister of Fire
Dec 28, 2006
16,348
Mt. Rainier Foothills, WA
When you use that HF moisture meter there is a high scale and a low scale. Your wood is not 0-4.5% so I suspect that you are on the high scale.
 

Highbeam

Minister of Fire
Dec 28, 2006
16,348
Mt. Rainier Foothills, WA
You are reloading when temps start falling below 550? So you're trying to run this thing at high output for lots of heat, that's fine, it can do that but the maximum burn times will only occur at the lowest output which means the max stove temps are nearer to 400.

You can have high heat with short burns or you can have low heat with long burns. There's no free lunch and only so much energy in a full firebox (tiny on the keystone). Even less energy available when the wood is wet.
 
  • Like
Reactions: Tenn Dave

Jo191145

Burning Hunk
Sep 29, 2013
175
Central Ct
Have you replaced the cats? If it's been abused you may want to.
I just started this year with my first cat stove. A Woodstock fireview 201 which is the first version. The 205 is the new improved version.
I replaced the cats simply because it was my first cat stove with no known history behind it. Not much sense in trying to learn new skills on something that may be broken. Turns out they weren't all that bad anyway but now I know.

Couple points. My bet would be your pushing that little Keystone beyond idle. Longest stated burn times are given at an idle. How much air are you giving it during the burn? That burn time includes the coaling stage which you are bypassing by adding more wood. That's quite OK to do if you need the extra heat and decide that's the best way to attain it.

You should do an air test on it. While it's burning run a barbecue lighter over all the seems. If it's drafting through bad seems you'll see it quickly. I had some on mine that needed repair. Mostly between the door frame and stone. I theorize mines not from overheating abuse but more from mishandling during all the transport mine saw before and maybe during the time I got it. I just used furnace cement from the local hardware store. Worked fine.

I can leave mine for twelve hours and usually have enough coals to start a fire. 8 hours no problem, usually still at 300 by then. When it's cold outside and I'm trying to keep from firing the wood furnace I can chew up wood just like you. Eventually get half a firebox full of red coals. It runs pretty good with the manual air fully shut, pretty much as intended. Let the cat do the work.

Bottom line both you and I are trying to heat homes at or above the max for the stove. It's not the stoves or manufacturers fault.
 
Last edited:
  • Like
Reactions: Tenn Dave

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
Something is not being read correctly or the meter is whacked. Super dry, unfinsihed flooring wood is 8%. Normal cordwood is 15-20% when nicely seasoned. Are you testing on a freshly split face of the wood (not endgrain)? Are you pressing the probes firmly into the wood grain?
I basically measured from the cut side of the log. Even though I'm new to all this, I was somewhat skeptical of a 0% reading. But, that's what it said. I think I'll split that same log and see what it reads.
 

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
I do a 14 hour burn almost every day of the winter in my Keystone. At the end of the burn, the house is 68-72F, with plenty of coals for a restart. The stove meets my heating needs. Greater heating needs = shorter burn times.

Where are you setting the draft during the burn? Usually expressed 0-4 for the KS or Fireview. My draft is usually 0-.5 during the burn. If my draft was set at 3 or 4 my burn time would probably be about as short as yours, and my house would be very hot. Also, too much draft flushes too much heat up the chimney and the cat can't efficiently burn the fast moving smoke. Woodstock recommends draft settings of 2 or less for efficient cat burns.

I think there is probably something wrong with your stove (air leak or bad cat). Or your home requires lots of heat and the KS isn't big enough for your needs.
 
Last edited:

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
Have you replaced the cats? If it's been abused you may want to.
I just started this year with my first cat stove. A Woodstock fireview 201 which is the first version. The 205 is the new improved version.
I replaced the cats simply because it was my first cat stove with no known history behind it. Not much sense in trying to learn new skills on something that may be broken. Turns out they weren't all that bad anyway but now I know.

Couple points. My bet would be your pushing that little Keystone beyond idle. Longest stated burn times are given at an idle. How much air are you giving it during the burn? That burn time includes the coaling stage which you are bypassing by adding more wood. That's quite OK to do if you need the extra heat and decide that's the best way to attain it.

You should do an air test on it. While it's burning run a barbecue lighter over all the seems. If it's drafting through bad seems you'll see it quickly. I had some on mine that needed repair. Mostly between the door frame and stone. I theorize mines not from overheating abuse but more from mishandling during all the transport mine saw before and maybe during the time I got it. I just used furnace cement from the local hardware store. Worked fine.

I can leave mine for twelve hours and usually have enough coals to start a fire. 8 hours no problem, usually still at 300 by then. When it's cold outside and I'm trying to keep from firing the wood furnace I can chew up wood just like you. Eventually get half a firebox full of red coals. It runs pretty good with the manual air fully shut, pretty much as intended. Let the cat do the work.

Bottom line both you and I are trying to heat homes at or above the max for the stove. It's not the stoves or manufacturers fault.
I did replace the cat. It is a new design (all metal and not ceramic) Bought it from Woodstock. But, I think you put your finger on my issue. I'm just running it full out expecting too much heat from it AND long burn times. The only physical problem I see is some draw from the ash bin door. I did an incense test over the exterior and saw incense smoke being drawn into this area. The other thing that I don't understand is smoke coming from the chimney. I thought cat stoves burned smoke. Anyway, I'll re evaluate my burn times by letting the stove cool to 300F and measure my time from initial burn to 300F. Thanks for your observations and advice.
 
  • Like
Reactions: fox9988

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
The ash pan leak needs fixed ASAP. It could be causing most of your problems.
The smoke you see is from too high a draft setting (and extra air from the leak). The cat needs time to burn the smoke, with high draft setting the smoke passes through the cat too fast to burn.
Try a burn with the draft set at 1. You should get more total heat out of the stove and no smoke (assuming the ash pan leak isn't horrible). Half of the heat may be going out the chimney with the draft wide open.
 

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
I do a 14 hour burn almost every day of the winter in my Keystone. At the end of the burn, the house is 68-72F, with plenty of coals for a restart. The stove meets my heating needs. Greater heating needs = shorter burn times.

Where are you setting the draft during the burn? Usually expressed 0-4 or the KS of Fireview. My draft is usually 0-.5 during the burn. If my draft was set at 3 or 4 my burn time would probably be about as short as yours, and my house would be very hot. Also, too much draft flushes too much heat up the chimney and the cat can't efficiently burn the fast moving smoke. Woodstock recommends draft settings of 2 or less for efficient cat burns.

I think there is probably something wrong with your stove (air leak or bad cat). Or your home requires lots of heat and the KS isn't big enough for your needs.
Wow, 14 hour burn time!! Well, I know I have a leak in the ask pan door. The gasket looks good but I'll replace it. After engaging the catalytic I set the damper to 1. I was closing it down all the way because I still saw flames in the firebox. I'm not sure if I'm running this stove correctly. Based on everything I've been reading I definitely need to make some changes. Right now during re-start in the morning I slowly heat the stove to 300F. I engage the catalytic and set the draft to less than 1. The flames are darker in color but there is a lot of flame activity in the firebox. I just let it go. In about an hours time the stove temp reaches 600 degrees and within 2 hours around 500. Then coals form and the temperature drops quickly. I notice that the cat doesn't seem to be burning all the woodsmoke. Could the problem be with the small amount of draft from the ash pan?? I'm not sure about any other internal seals (like the seal the cat sits on) or areas that need cement. If I leave the stove run at 0.5 setting with the cat engaged and a full load of well seasoned wood.......what should I expect. I'm not feeling huge amounts of heat. The room the stove is in is only 400sqft but it is long and narrow with drafty windows.

Thanks for responding Fox9988. Glad to be speaking with someone that owns a Woodstock stove!
 

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
With your stove working properly and hard wood, your stove should burn 14 hours anytime you want it to. But don't expect it to necessarily meet your heating needs. My house is almost new, Very tight and well insulated and only 1532sqft heated.
The Fireview and Keystone are very similar. You will probably find more threads with advice for operating the FV, I find the advice interchangeable with my experience.
The technique in your last post sounds right.

I leave the stove run at 0.5 setting with the cat engaged and a full load of well seasoned wood.......what should I expect
A 14 hour burn with hard wood. Stove top above 400F for about the first ~8 hours of the burn (guessing here).

Do you see the cat glowing often? Mine glows red hot for hours during a burn.
 

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
Could the problem be with the small amount of draft from the ash pan??
Absolutely.

It may be leaking a lot more air than you realize. When you set the draft to 0, do the flames all extinguish within a couple of minutes? They should.
I burn at 0 often, depending on weather.
 

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
@Todd has a lot of KS experience and great advice. Hopefully he will weigh in.
 

radtechrad

New Member
Jan 11, 2015
22
Pennsylvania
Absolutely.

It may be leaking a lot more air than you realize. When you set the draft to 0, do the flames all extinguish within a couple of minutes? They should.
I burn at 0 often, depending on weather.
No, the flames don't extinguish. Usually I see "normal flames" burning albeit darker in color, and I see what I would describe as an aurora of flames. Very nice to look at. They kind of appear and disappear moving across the top of the firebox.
Since reading your replies I forced myself not to add any wood to the fire. About an hour ago the temp was 500 on the stove top. It is now around 425. I'm thinking I'll be at 300 in 2 hours (that's pretty conservative). So, from the last time I added wood I'm guessing my
burn time to get me back to 300 degrees is approx 4 hours. That's with the draft at 0.5 with the cat engaged.......and a slight draw to the ash pan. Doesn't sound quite right.
 

fox9988

Minister of Fire
Jan 15, 2012
616
NW Arkansas
No, the flames don't extinguish. Usually I see "normal flames" burning albeit darker in color, and I see what I would describe as an aurora of flames. Very nice to look at. They kind of appear and disappear moving across the top of the firebox.
This sounds like my stove set on 1 to 2. There should be no flames on 0, the wood should smoke/off-gas and the cat burns that for heat.
I would recommend you try a burn on 0 and see if that helps.
 
  • Like
Reactions: Jo191145
Status
Not open for further replies.