Please help... Jotul F305 driving us mad.

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autopilot

New Member
Feb 12, 2020
4
UK
Hey there. I’m in the UK, but found this great forum and I’m hoping you can help me out with my Jotul. I’m not new to wood stoves, had a Clearview (if anyone knows that brand) in my last house for 20 years. Never had a problem like this. In fact we have another in my new house which works great too.

So we have a newly built large house with two stoves. We have a chimneys on each end of the house that are constructed exactly the same. One has another Clearview that seems to work perfectly, just like in the old house. We just recently added a Jotul F305, but we just can’t get to burn well, rarely about to get it about 400 degrees with lots of door cracking, but usually just about 300. This is with both levers to the right (air vent and ignition vent open), no mater how long it’s left. Having the door cracked helps. This is with well seasoned store-bought dry wood (I have a moisture meter, it’s below 20%). Fuel quality isn’t the issue here, I’m certain of that. With the Clearview if you open the ignition vent the stove roars and get very hot very quickly, easy to get it over 500 in no time. Because the Clearview stove works so well and wood is good, I think something is wrong with the Jotul, I don’t think it’s pulling anywhere near enough air though. Could something have been set up wrong when installed?
 

Woody Stover

Minister of Fire
Dec 25, 2010
12,290
Southern IN
What is your chimney setup..insulated liner up to the top of the chimney? What is the height?
Can you tell where the ignition vent air comes in? Is that what we call "boost air," that comes in below the door opening?
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,535
South Puget Sound, WA
Are your other stoves the Vision 500? I don't think the Clearview stoves have the robust secondary combustion system that the Jotul does. The F305 will need decent draft to perform well. Can you answer webby's questions about the flue system?
 

Woody Stover

Minister of Fire
Dec 25, 2010
12,290
Southern IN

Woody Stover

Minister of Fire
Dec 25, 2010
12,290
Southern IN
Yer all corny. ;lol
And we wear beanies. ;)
1581574521661.png
 

prezes13

Minister of Fire
Jan 12, 2014
937
Connecticut
Not to be a nuisance but that great well seasoned store bought wood is it really at 20% mc? Did you measure it on a face of a fresh split of a piece of wood that was a room temp? Most of the time the culprit is the wood.
 
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autopilot

New Member
Feb 12, 2020
4
UK
Yeah, tested the wood.

The chimney is quite tall. We are exploring issues with the chimney, but I was wondering if there are any adjustments or issues with the stove.
 

SpaceBus

Minister of Fire
Nov 18, 2018
7,095
Downeast Maine
Do you have any untreated lumber cut offs or scrap? That will determine very quickly and easily if the wood or the chimney is the issue.
 

wild_thing

New Member
Nov 1, 2021
3
Austria
Hello,

We own a Jotul F305 and experience similar problems. This is the 4th wood stove I own, and the 2nd Jotul.
The F305 seems to have a rather small air inlet. I never had a wood stove that has so little air coming in. Other stoves can easily create a blazing fire, this one not.

Not sure if something with the levers was wrong, I once removed the plate on the bottom that holds the levers. Nothing seemed wrong. But I was astonished to see, how small the air vent is dimensioned-only a few square centimetres (approx 30cm2) where the incoming air has to squeeze through. Mounting the bottom plate again is rather difficult, if you do it with the stove standing upright. A second person might be very helpful.

The ignition lever doesn't do a lot. For sure it doesn't add extra air. I think it focuses air more to the center (lever right),or more evenly from below (lever left).

Greeting from Vienna.
 

SpaceBus

Minister of Fire
Nov 18, 2018
7,095
Downeast Maine
Hello,

We own a Jotul F305 and experience similar problems. This is the 4th wood stove I own, and the 2nd Jotul.
The F305 seems to have a rather small air inlet. I never had a wood stove that has so little air coming in. Other stoves can easily create a blazing fire, this one not.

Not sure if something with the levers was wrong, I once removed the plate on the bottom that holds the levers. Nothing seemed wrong. But I was astonished to see, how small the air vent is dimensioned-only a few square centimetres (approx 30cm2) where the incoming air has to squeeze through. Mounting the bottom plate again is rather difficult, if you do it with the stove standing upright. A second person might be very helpful.

The ignition lever doesn't do a lot. For sure it doesn't add extra air. I think it focuses air more to the center (lever right),or more evenly from below (lever left).

Greeting from Vienna.

Have you tested the firewood for water content? If it is above 20% you won't get a blazing fire in that stove. Air from below makes a big difference compared to air from above, if that is what your ignition lever does.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,535
South Puget Sound, WA
Hello,

We own a Jotul F305 and experience similar problems. This is the 4th wood stove I own, and the 2nd Jotul.
The F305 seems to have a rather small air inlet. I never had a wood stove that has so little air coming in. Other stoves can easily create a blazing fire, this one not.

Not sure if something with the levers was wrong, I once removed the plate on the bottom that holds the levers. Nothing seemed wrong. But I was astonished to see, how small the air vent is dimensioned-only a few square centimetres (approx 30cm2) where the incoming air has to squeeze through. Mounting the bottom plate again is rather difficult, if you do it with the stove standing upright. A second person might be very helpful.

The ignition lever doesn't do a lot. For sure it doesn't add extra air. I think it focuses air more to the center (lever right),or more evenly from below (lever left).

Greeting from Vienna.
The stove design may rely on a strong draft. What does the manual say is the minimum chimney height? There are several things that can reduce draft even with a proper height chimney. Describe the flue system for this stove from the stove body to the chimney cap. Include piping and flue liner diameters, 90º turns, and whether the chimney is interior or exterior. Also, does the stove perform much better when outside temperatures drop below 5ºC?
 
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Woody Stover

Minister of Fire
Dec 25, 2010
12,290
Southern IN
Yeah, tested the wood.

The chimney is quite tall. We are exploring issues with the chimney, but I was wondering if there are any adjustments or issues with the stove.
As begreen inquired, how tall is it, from the flue exit of the stove to the top of the chimney? Is the chimney a properly sized liner, or a masonry chimney. If masonry, what are the inner dimensions of the clay tile liner?
I was astonished to see, how small the air vent is dimensioned-only a few square centimetres (approx 30cm2)
That opening is pretty large, actually, and the stove should be getting plenty of air through it.
I can't get the air inlet size of my stove, since I have the rear heat shield installed, but I will measure the opening on my SIL's Woodstock Fireview when I go over there today..
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,535
South Puget Sound, WA
The stove has more than one air inlet. The odds are that is not the issue. Our larger T6 stove's primary air inlet is about 25 sq cm. But there is also a secondary air inlet and a boost air hole too.
 

wild_thing

New Member
Nov 1, 2021
3
Austria
Thanks a lot for your replies!

@SpaceBus: The wood is several years old, stored dry outside, and has been inside since a year. The very same wood burns excellent in our Jotul F163 in the other house. On the F163 I have to limit the incoming air, otherwise it blazes far too strong. With the F305 there seems never to be enough air. If there is a blaze'ish moment it's with the door open.

@begreen: The flue is modern, ceramic, isolated, diameter 180mm, length approx 6m, approx 5m50 running inside the house, completely vertical. No cap on top, cleaned by the chimney sweeper just a week ago. The horizontal stretch in the pipe between stove and chimney is 1m20, with two 90° knees (each with two 45° angles - the good stuff). Vertical pipe 1m; pipe diameter 150mm. This is almost the same pipe setup I have with the F163, but with an much taller chimey. So the draft should be better, not worse.

On the same chimney I operate another wood stove for central heating. Not in parallel, though, even if that would be possible and allowed here in Austria. This other stove experiences a lot of draft. Originally I suspected that when using the Jotul F305, the the chimney would suck too much air through the other stove's exhaust, thus using reducing the draft for the Jotul. So I temporarily closed the corresponding opening in the chimney to make sure that no air is sucked in here. The result was more or less the same - still no good draft for Jotul.

Outside temperatures between 2° and 20° make no significant difference.

We do not use outside air supply as this is a 200year old farmhouse that is rather spongy, but never air tight.

The opening for the air inlet thats visible from outside is not what limits the flow. The limiter are two square holes in a metal blade, that is operated with the main lever.
 

begreen

Mooderator
Staff member
Nov 18, 2005
96,535
South Puget Sound, WA
The horizontal stretch in the pipe between stove and chimney is 1m20, with two 90° knees (each with two 45° angles - the good stuff).
Was the stove properly converted from top vent to rear vent? It looks like there is an exhaust deflector that needs to be removed when doing this. Was it taken out?
Screen Shot 2021-11-09 at 9.44.16 AM.png

The chimney is tall enough but the1m horizontal stretch may be a problem. This stove may need stronger draft than the F163 in order to pull air through the secondary combustion system. When combined with the two 90º turns the flue gases may be getting slowed down to the point of backing up.

If you can post a picture of the stove and flue connector we may be able to suggest a solution.