Leaving a Fire Alone....

[jadm]

I am home a lot during the day and have gotten into the habit of opening the primary air up as a load of wood burns.

I start with primary air wide open and let stove reach 450 - 500* and then begin to shut down air as far as possible. When coaling starts after about 4 or 5 hours later I begin to open the primary air back up in stages. My thinking being that coals will burn more efficiently given more air over time.

Yesterday I was out for a long stretch of time and made no adjustments at all. Air had been shut as far down as possible and left there. Came home and coals were doing just fine burning down without my care. ;-P

Which made me wonder if my fiddling is not only unnecessary but also not efficient as it may be letting too much air into the firebox thus cooling it down by sending more heat up the chimney.

So - how what do you do with primary air throughout your burn cycles and how does it effect your coals? (I do know about adding a log on top of coals when too many have accumulated.)

Thanks!

 

[edthedawg]

Sounds like you may do the exact opposite of others - we leave the primary full closed for longest burns. open about 1/4 for hottest burns. You were ok w/ the coals themselves when you got home after your extended absence, but were you ok w/ the heat in the room, too?

I don't think coals necessarily burn more efficiently when given more air late in the cycle, but it certainly does increase the late heat output (if you consider that efficiency, then you're all good)

 

[gzecc]

My thinking is also the reverse. The objective (non cat) is to get my 400lb steel insert to 500 deg. To do this I must burn wood. While buning wood a lot of smoke is initially produced (open inlet open flue). When the steel is heated (>30min)I want to hold as much heat in the box (close flue, close air inlet) and slow the burn down to make it last. This reduces wood usage and maximizes heat output.

 

[jadm]

Yes, heat in the room was fine. It was warm (45*) out yesterday.

I can't get air fully closed or else I loose flames and chimney begins to smoke. Usually get it about 75% closed. Setting depends a lot on outside temp. The colder the better this unit burns. It is still new to me and I am still learning how it operates.

So are you saying that I can go ahead and just leave things be to burn as they will and only open primary if I want more heat out of the coals and into the room?

 

[04RevX]

Usually people open the primary when the initially load it up and then gradually close it. Get a good burn going with the primary open and close it down and be on your way. Should be fine for however long your burns are. Sounds like you are doing the opposite.

 

[Cearbhaill]

I load with it open, then once things are going well and I shut the air down I don't go back until it is time to reload.
Once in a while (if it isn't too cold outside and I am really trying to extend the life of a coal bed and conserve wood) I may open it a tid bit during the last 10% of the cycle, but it's just as easy to go ahead and reload and get the cycle going again.

 

[jadm]

Sorry- I wasn't clear. Yes, I leave air wide open until fire is established and temp. is around 450-500* and then I begin to shut primary air down in stages as far as it will go and still maintain a flame and no smoke out the chimney.

I was referring to later stage in burn times after 4 or 5 hours and mostly coals remain with larger pieces in back of the firebox. That is when I begin to open primary air up. After yesterdays experience I am thinking that I can just leave it alone and it will burn the coals down without additional air....

My old insert used to get a lot of coals that I had to scoop out because I couldn't burn them down and the room temps. would drop. I had to open air. I just carried the practice over to this insert and now I am thinking it is unnecessary because this one is much more efficient at burning them down without me tampering with the air setting.

P.S. I went back to original entry and edited it to reflect what I have written here.

 

[karri0n]

You're actually probably sending more of your heat up the flue using this technique. The secondary air, which is never closed off all the way, will continue to provide air to the coals. You might even try closing the primary the rest of the way when your wood is all coals, as they won't produce any smoldering/smoke when in the coal stage, and will therefore remain in the firebox longer. Your heat output may drop, however.

 

[gpcollen1]

I think it sometimes depends on how much heat you are getting and how much you want out of the stove sometimes. If you end up with excess coaling, a great solution is to pile them up toward the front and throw one split on top. I leave the air open full or cut it back some to get a good hot burn out of it, reduce coaling and get some great heat as I look to load the stove back up to the gills for an extended burn.

 

[edthedawg]

PerPlexed - you should be ok - but i'm curious why you can't shut primary air down past 75% without the fire snuffing out. Your OP said you "shut the air as far down as possible" which I took to mean the full closure of the stove, but you're not going near that far. Very odd. Makes me really wonder what's going on there.

And you're shoveling coals out every day?? Huge piles of charcoal is definitely a sign of a problem. I'm not well-enough versed to speak intelligently about it, but IIRC it has to do w/ being too hot, too fast.

What are your coal-to-coal times?

 

[Pagey]

I can't shut down the primary on my Endeavor all the way, either. I can get it close, but if I lose the visual secondary burn, I have smoke from the chimney every time. I'm burning pine that tests 15-20% moisture and red oak that tests from 18-25% depending on the size of the split. It would be nice to just be able to shut all the way down, but I've come to accept that this is just something I cannot do with my stove at this point.

 

[struggle]

While I do not have your stove I have found the less fumbling around with the stove controls the better the heat output is.

For me load high burn ten minutes on a solid base of coals until flue temp probe gets around 750-800 then shut the primary air all the away down and close the dampener on the pipe 50%.

It just seems to me the less I have to fidget with the stove the happier I am.

 

[pen]

Do you keep something with water in it on your stove to humidify air?

I compare how my stove is burning a load of wood and its heat output by the amount of water that is being evaporated.

If I make a change, burn a few loads, and still evaporate the same amount of water as usual, then I know I really didn't change anything.

The only other way (without using some electronic devices) would be to place a stove top thermometer on the unit, and through direct observation, record the burn temps every 30 mins over the course of a load and compare to the temps you achieve after making changes (graph the results if you wish). Obviously you would need to do several trials to get a consistent basline.

pen

 

[Yamaha_gurl]

Pen, you just leave your fisher alone eh? See I mess around with it as well. Once my flue temp starts dropping I start opening up the air, thinking if the flue temp rises I will get more heat. Now reading here, this isn't correct is it?

 

[jadm]

PerPlexed - you should be ok - but i'm curious why you can't shut primary air down past 75% without the fire snuffing out.
And you're shoveling coals out every day??

What are your coal-to-coal times?

Old insert I could shut air down all the way. THis one is different and I have come to accept that though I still try to get it down all the way. It is much bigger than my old insert and I live a mile high in elevation which may or may not be a factor. I know outside temps. and wind conditions make a difference. Just a lot of variables going on.

I shoveled out coals in my old insert. Not this one. I have enough to start up again. THey burn down very well in this insert.

Coal-to-coal times vary due to load and temps. so I can't really say. If house temp. stays warm I just let coals go and build a new fire in the evening...

 

[jadm]

Do you keep something with water in it on your stove to humidify air?

I compare how my stove is burning a load of wood and its heat output by the amount of water that is being evaporated.

I have an insert.

I have a crock on the hearth but I also have a cat who has taken it as her personal water dish therefore I can't tell how much has gone to evaporation or to cat hydration. 8-/

I took notes for awhile and that really drove me NUTS :gulp: . Now I am looking for ways to relax and enjoy and leave things alone to manage on their own...

 

[pen]

Pen, you just leave your fisher alone eh? See I mess around with it as well. Once my flue temp starts dropping I start opening up the air, thinking if the flue temp rises I will get more heat. Now reading here, this isn't correct is it?

Most of the time yes.

Now today, since we are in a cold snap and the house was 61 degrees when I got home, when it starts to coal down I'll only put a split or 2 on, and open the drafts up to get a little more heat, burn the coals down quicker, and make room for more wood before bed.

pen

 

[LLigetfa]

Yes, heat in the room was fine. It was warm (45*) out yesterday.

That not even freezing temps. When it's that mild out, the heat stored in the thermal mass of the home can linger for a long time. Try the same test in bitter cold.

My stove didn't have any way of adjusting the (primary) air at the doghouse. It had only a 3/8ths inch hole. I experimented with blocking the hole and while it slowed the burn, it increased the coal buildup. As the coals built up, there was less room for wood and so the stove could not keep up with demand on bitter cold days.

Enlarging the hole did the opposite. I added a control to it now and run it wide open when home and awake (to burn down the coals) if it's cold out but close it down when mild out, if I want to preserve the coals for an overnight burn, or if we are away from the house for several hours. I notched the control so that it is impossible to close it off completely.

Some primary air comes from the air wash for the door glass which, on my stove is regulated by the secondary air control. The air wash is a curtain of air that rolls down the door and onto the coals at the front. If the coals are pulled forward and the stove is loaded to burn front to back (E/W), the doghouse and the air wash affects the fire different than if it is loaded N/S. A blasting doghouse tends to burn a tunnel through the coals that draws air from the air wash in.

 

[LLigetfa]

Now today, since we are in a cold snap and the house was 61 degrees when I got home, when it starts to coal down I'll only put a split or 2 on, and open the drafts up to get a little more heat, burn the coals down quicker, and make room for more wood before bed.

If indoor humidity is high, letting the indoor temps fall like that will drive the RH too high and frost windows and condense on exterior walls which could result in mold issues.

My gas furnace is set to come on at 69, notletting it get that cool. None the less, it was so cold yesterday that I built up a lot of coals getting the house up to 76. The house cooled to 71 while I burned down the coals an hour before bedtime.

 

[vtdavid]

If I end up with to many coals like when I'm ready for bed and the five hour fire get home from work fire hasn't burned down the coals down, I pull the chunks forward and open the draft about 1/4. In a short while the coals burn down and the stove is hotter for the next load.

 

[pen]

Now today, since we are in a cold snap and the house was 61 degrees when I got home, when it starts to coal down I'll only put a split or 2 on, and open the drafts up to get a little more heat, burn the coals down quicker, and make room for more wood before bed.

If indoor humidity is high, letting the indoor temps fall like that will drive the RH too high and frost windows and condense on exterior walls which could result in mold issues.

My gas furnace is set to come on at 69, notletting it get that cool. None the less, it was so cold yesterday that I built up a lot of coals getting the house up to 76. The house cooled to 71 while I burned down the coals an hour before bedtime.

That could be a problem in a house that is a bit tighter than mine.

Plus, I don't keep the RH that high when the house is warm (45% tops)

pen

 

[Heem]

this is all great information here but boy am I getting overwhelmed by how to set the air and this and that.

I guess I'll learn eventually.

 

[pen]

this is all great information here but boy am I getting overwhelmed by how to set the air and this and that.

I guess I'll learn eventually.

There is NO set rule of thumb. You put the same stove into 10 different houses and each one will have its own personality because of the location of the stove in each house, type of wood, condition of wood, size of the wood splits, the type of chimney, location of chimney, size of chimney, outdoor air temperature, prevailing winds, etc, etc, etc.

Use good common sense, good wood, and monitoring devices (such as a thermometer) where appropriate, keep up with your maintenance, and the stove will treat you well.

 

[ansehnlich1]

Most of the time I can't shut the air down all the way on my Oslo.....I'll lose secondary burn and start to smoke. I can get down to an 1/8th open, or even a bit less, but seldom close it the whole way.

Only time I open 'er up at the end of a burn cycle is if I'm trying to burn down the coals, and that's only when I'm burning real hard cuz it's cold outside.

I loaded the Oslo this morning at 5:15 a.m. I'd say the temps all day here were no more than 25 degrees outside. When I got home at 4:15 p.m. it was 68 degrees F. in the living room.... that's ok with me

 

[LLigetfa]

There is NO set rule of thumb...

You're so right. I had the same model stove in my former stove and behaved very different there.