Jotul F45 air control

[skeenut]

So far I'm happy with our new Jotul Greenville. Loads and starts up easily and is burning through the night leaving us with a nice little pile of embers in the morning.
My concern/question to the group is around air control. Our stove is burning nice and hot, BUT, I'd like to be able throttle it back more than I have been able to so far. I get a nice little fire going with three splits and get the damper shut close to if not all the way. Stove top typically about 500. So far so good. Then I add more wood, like three to five splits, with the intention of establishing a long slow burn. My procedure is to open the door, add the wood, and close the door. No opening the damper or cracking the door needed. The fire re-establishes itself and rather quickly the stove top temp rises past 600 to between 650 and 700. And sits there for a few hours until the fuel becomes a bit exhausted.
Early on learning about the stove, after break-in burns, I had the stove get above 800 and learned to gradually build my fire and keep the damper close to shut ASAP to control the temp. But I would like more control.
Is there a way to further starve the stove to get or keep temps down? And what temps do F45 owners routinely achieve and run at?
Thanks,
Jeff

 

[Creekside]

I have an F55 so I think it is basically the same as the F45 just bigger. From a cold start I will generally get mine going with a couple regular splits and kindling. Once it gets going, around 200 degrees, I'll fill up the firebox as much as I can and close the door. If I'm burning madrone, which is the densest hardest wood we have around here, I'll start turning the air down when the secondaries start going crazy, usually around 300-350 with that wood. Doug fir I will start turning the air down around 4-500 because it doesn't burn as hot as fast. When I reload the stove on a bed of coals, if I want maximum heat, I fill the box as full as I can.

1., I don't think regularly going in the 650-700 range is good for the stove, that's too hot for my liking and you're using a lot of your heat at the beginning. I get nervous when it's close to 600, because even if you shut it down all the way, the temperature will still rise for a little while.

2., if you want a long slow burn, you need to pack the firebox full as soon as you have a good enough starter fire and draft going. By waiting until the stove is at 500, the first load of wood is well into the off gassing phase and then you're adding more wood that's starting at the beginning. So you're expending a lot of your heat at the beginning.

I easily get 8 hours burns with doug fir by filling up the box with 6 decent splits and then I turn the air down in usually three increments once it's around 500. I can get 10 hours without too much trouble and stretch it to 12 hours when I really pack it full of madrone and turn it down just right. I rarely close the air control all the way. It's usually 75-90% closed, but I have two 90 degree bends in my pipe and chimney. A

Also where exactly do you have your thermometer on the stove top?

 

[skeenut]

Hi Creekside,
Thanks for the response. Very clear and helpful!
My thermometer is a bit top of dead center on top of the stove.
And my only solace is that the Jotul manual says the optimum burn temperature is between 400 and 700.
I am going to try your method: Get a fire started with a few splits and kindling and then, much quicker than I have been doing, load the stove to capacity and keep the temps down by feathering the damper closed. My error has been getting a hot fire, meaning 350 to 400 or so, established with two or three splits so they are well into the off-gassing state, and then incrementally adding more fuel.
My method has led to huge hot spikes in the early stages with a kind of rapid fall off.
I'll report back in....
Thanks again,
Jeff

 

[Creekside]

I put mine in the corner of that top plate because I think that's what the manual said. Your temps probably aren't bad then because that is the hottest part of the stove. The other thing I watch is the chimney. I found 500 to 550 is a good spot for my stove because I consistently get little to no smoke coming out the top of the chimney.

Sent from my SM-G930V using Tapatalk

 

[Zack R]

How was the rest of the winter with your F45?

 

[skeenut]

Hey Zack,
Quit good!
I've got my process down pretty well. I end up with some nice embers in the AM and can easily rebuild a fire without any trouble. After raking the embers so they are mainly at the front of the stove I load right up again to capacity and only need to sort my split so that the smallest most splintery ones are at the bottom. I leave the door cracked open for a few minutes, just until I have the beginnings of flames. Then I shut the door with the air control wide open and feather it down over the next half hour or so until it's about one quarter to one third open. Burn for about six to eight hours and old it up again. Repeat one more time a bedtime, about 11:00 PM and start over again in the morning around 7:00 AM.
If it's really cold out the intervals between reloads just get shorter and I do four or maybe five loads daily instead of three.
Looks like I'm going to use about four cords.
I really like the stove. Lights easily, loads easily and now that I've figured it out it controls easily. The glass stays clean too and the burns look good.
I was skeptical of not have an ash pan but it is very much a non issue. In fact, I no longer see an ash pan as an advantage. I'm happier with the extra moving parts and gaskets with potential air leaks. And no more temptation to open the ash pan get a ripping Bessemer Furnace air flow through the wood for a sure start. (A friend of mine did that occasionally. Not me. )
Moved the thermometer to the chimney connector, about a foot above the stove top. This was on the recommendation of a chimney sweep I hired. Who, BTW, removed a stunning , choking amount of creosote. I am assuming that I was responsible for the remarkable build up because the PO had so severely overfired his beautiful Heritage Soapstone that it was WUBAR and burned it that way for some time. WIDE open. Not exactly conducive for creosote build up. I removed his broken stove and simply slid mine into place and reattached the chimney connector. I had minimal creosote chips fall out and my stove burned just fine, with no draft problems. That is until my second cord. I began to hear the fluttering crinkle of potato chips in the connector. All the time. And the draft got sketchy, and the draft got bad. So, In came the chimney sweep. The stove top baffle was full of chips and they were backed up into the connectors about a foot and a half. The critter screen was choked close too. So we cleaned it up and brushed it all out. And it's back to a good draw. No duh. Just starting up on the last cord so we'll see. I think I'm burning a bit hotter, keeping the chimney connector at about 300 to 500 on it's new home on the chimney connector.
I never had a creosote problem like that before ever.

 

[Knots]

How good is your draft? I have a straight 26-foot pipe that mostly goes through the heated house. It pulls hard on my F55. I had to tape-off a good part of my secondary intake.

 

[skeenut]

I have the stove installed in a one story ranch. The room is a cathedral ceiling, about fourteen feet high at it's peak. The chimney connector goes straight up, no bends, near the peak and connects to about four feet of double wall.
My draft is good. But I do get creosote build up that chokes it down.

 

[Zack R]

Sounds like its going well. I've also had a successful first year thus far with my F45 and I'm looking forward to it doing even better next year since I will have a drier firewood supply. I've run three cords through it, will probably finish the fourth by the end of winter.

I haven't cleaned the chimney yet but did need to clear off the chimney cap screen back in December. The draft has been strong (2 story house, chimney is at least 30') and the glass is always clean. I'd be interested to see how it does with hardwood as I've only used pine (I live in a pine forest and its readily available).

 

[KennyK]

I have the stove installed in a one story ranch. The room is a cathedral ceiling, about fourteen feet high at it's peak. The chimney connector goes straight up, no bends, near the peak and connects to about four feet of double wall.
My draft is good. But I do get creosote build up that chokes it down.

Great to hear more about the F45! How big is your whole house, and are you heating all of it with the F45 or just part? What are your temps like in the stove room and other parts of the house that you're heating with it?