Jotul Castine, Difficulty reaching optimum temperatures

[Ski-Patroller]

We recently replaced our 33 year old Garrison I with a Jotul Castine. It is a used stove but seems to be in great condition. I went through it pretty well before we installed it, and all the gaskets were good and it seemed very tight, and clean inside. We have 24' of 8" flue, the first 12' are single wall steel and the other 12 are insulated stainless steel. We burn Douglas Fir and Larch. It is seasoned for at least two years, and probably more.

We have difficulty reaching the optimum burn temps with this stove. So far the only way we have reached 600 on the stove top, is by burning with the ash door cracked. Once we get the stove to temp this way, closing the ash door will drop the temp and the fire looks like it is short on combustion air. When the stove it hot, I can see flames around the secondary air holes so I think that is working OK. The primary air damper does affect the burn rate, so it appears to be working. It seems like it does not let in enough air when wide open. I don't really see where the primary air comes into the interior of the stove. I looked at the slide damper, (opened the inspection cover) and I can see how it works but I don't know where the air goes once it is past the damper.

In general this stove burns great if we crack the ash door, but with it closed we just don't get to the expected operating temps. If it is at operating temp, and we close the ash door completely the temp will drop, typically below 400. I don't think the draft is a problem. We have about 0.09" w.g. measured just above the stove, when it has been running for a while. It seems to draw pretty well with the main door wide open also.

Any comments or suggestions about problem areas in the stove or our operating technique? It seems to me that once the stove is good and hot, It ought to stay that way with the damper wide open. Also we can't keep the glass from blacking up, even with the damper wide open. If the ash door is cracked the glass will self clean.

 

[weatherguy]

First thing you have to look at is the fuel, how seasoned is your wood? When was it split? Sounds like a wood problem, these newer airtight stoves need good, dry fuel to burn properly.

 

[USMC80]

You say the wood is "seasoned" 2 years or more, so I am assuming it was split and stacked for 2 + years?

 

[Ski-Patroller]

This wood has been split and stacked in my basement for at least one year. It was dry and ready to burn when I bought it last year. I'll check the actual moisture content when I'm up at the cabin next. The wood I got this year is at about 14% moisture right now. We aren't using it yet. (I'm a wood worker and have a Ligno Moisture Meter)

 

[DAKSY]

Just my $.02, but I'm thinkin you need an in-line damper in your connector pipe. 24' feet is a long run for that Castine, & that 8" flue might be sucking everything out of the combustion chamber before you get the heat out of it. With a 6" run, we always recommended a damper for ANYTHING over 22'...

 

[begreen]

How is the stove vented - rear exit or top? Is the connection straight up to ceiling support box or are there a couple 90 deg turns on the way up to an exterior chimney?

The stove is meant for 6" pipe. Switch out the connector to 6", double-wall preferred. Don't use the ash pan door as an intake. You will crack the grate and possible the base in short order. That makes for a very expensive repair.

Also, tell me how you are managing the stove and fire in detail. It will start and burn differently than the old Garrison.

 

[Ski-Patroller]

The stove is top vented. No elbows or tees. I know Jotul says 6" but they also say not more than 2x flue area, and we are well under that. Draft is just under 0.1"W.G.

Our typical light off is to put some kindling and a couple of small splits in the firebox with a little newspaper on top to get the flue warm quickly. I usually use a pizo propane torch for lighting fireplaces and wood stoves. After lighting the kindling, we burn for a few minutes with the damper wide open and the main door or ash door cracked open. I would prefer to use the main door and shut it after 2-5 minutes, but our best results are to run with the ash door cracked open until we get to 400-600 on the stove top. Even then, once we close the ash door the temp will drop, and I don't think we have been able to maintain 400 with only the main damper open. Because this stove is at our cabin, and it has not been very cold yet, we are still experimenting. While I realize that our startup may not be optimal, I would think once we reached 400deg + we ought to be able to run the stove as described in the Jotul manual.

I don't see much mention of actual stack draft in W.G. Because I do some HVAC work and also combustion setup on industrial furnaces and heating boilers, I'm used to using draft gauges, IR guns etc in setting up equipment.

Where does the air enter the firebox from the damper box ( area under the inspection plate)?

 

[begreen]

The air enters at the bottom rear of the stove via a 3" ? round opening. Instead of using the ash pan door for starting, open the main door instead just a little and leave it ajar (while in the room) until the fire gets going. If draft is sufficient and the splits are dry you should be able to sustain a good fire. Then, as that blaze grows add some more wood, somewhat diagonally so that you don't snuff the fire. Leave the door ajar again for another few minutes until the new wood catches fire. Then close the main door. Now, incrementally lower the air supply. Go until the fire just starts to get lazier and stop. Let it burn like this until the flame grows again in intensity. Then repeat with the lowering of the air supply until the flame are lazy. By now you should be down to about 3/4 closed. Repeat if you can (depending on draft this may be the ideal running spot for the air control).

One trick I used for a faster start is to place two shorter, 2" splits or kindling in the center of the stove, about 3" apart, loaded N/S (parallel to the stove sides). Then put some newspaper balls between these sticks (or use a SuperCedar chunk). Now lay on some 2" splits E/W lincoln log style and with some kindling mixed. The reason for this is that there is a small amount of boost air coming out from the front bottom center of the firebox. This air shoots right up the center of the those two N/S pieces and helps start the fire quicker.

 

[Ski-Patroller]

We will work on our fire building techniques, but I'm still concerned since even after I have a very hot fire and stove, the max damper won't maintain 600 (or maybe even 400) degrees. Generally it seems that if I damper the fire down any, it goes down and does not subsequently build back up, but I'll need to watch that more in the future and see.

Do you know where the air actually enters the fire box, after the damper. I know that some comes in right around the inspection plate, and the European and North American Plates are different. Where else does the air enter the firebox?

 

[begreen]

What do you mean by max damper? Max air can actually cool down the fire because it reduces secondary burning.

This stove will not burn like the Garrison. 600-650F is normal cruising temp for this stove. If you damper the stove down (using the stove's air control) the flame should shift to secondary burning. It's when you get ghostlike wafting flames that the stove top will get the hottest. The primary air is mostly ducted up to the airwash for the front door, though there is a small boost manifold at the bottom front and center. Secondary air is unregulated. If the draft is good and the stove is warmed up, as you reduce primary air the vacuum of the draft pulls more makeup air through the secondary tubes.

 

[Ski-Patroller]

Thankshe damper settings some more. I assumed that maxim opening would produce the hottest fire. Especially since cracking the ash door always heated up the stove.

I'll experiment with t
I haven't seen the slots or holes for the air wash. I'll have to look more closely for them the next time I'm at the cabin.

 

[begreen]

By cracking the ash pan door you are essentially creating a forge under the fire. The sudden heating in a concentrated area is why this often cracks the grate and sometimes the base of the stove. When you have the ashpan door correctly closed and and the front door too, the firebox is in a controlled state. The air control regulates the balance. Have it wide open for starting the fire and incrementally reduce the air as the fire gains strength. This is a willing heater. Try to keep the stove top temp to 700F or below to lengthen the life of the stove.

 

[Ski-Patroller]

Thanks for your input.

We will try working with the stove more the next time we are at the cabin. I will also get the stack temperature a the ceiling as well as right out of the stove. I'm curious how much it cools in the 12'

 

[begreen]

Sounds good, you're welcome. FWIW, it took me about a month working with the F400 before I felt I had mastered it.

 

[PLAYS WITH FIRE]

Could it be the temperature outside why draft may not be so strong...weather says in Gov't Camp, Or. is only in the higher 40's at night?

 

[begreen]

That and the altitude may not be helping if the cabin is up near the summit.

 

[Ski-Patroller]

We are getting better burns now. When the cabin gets warm the stove draws better, because the flue is still pretty warm 12' up. I was measuring 250+ at the top of the 8" single wall pipe this weekend, 550 or so at the stove pipe leaving the stove top. We are going to replace the 8" single wall with 6" double wall Duravent. That should make it easier to keep the flue hot all the way up to the 12' of 8" insulated pipe going through the roof.

The only real dislike of this stove is that it is hard run a fire all night. We usually have enough coals to get the next fire started, but there isn't much heat. It does put out a lot of heat and it keeps the glass clean when it is burning at 600+ degs.

 

[Kevin Dolan]

Sounds good, you're welcome. FWIW, it took me about a month working with the F400 before I felt I had mastered it.

Begreen you obviously know how to run stoves. I have been running the f400 for three years and am still a novice. I was surprised at your stove top temps of around 600, I tend to run around 500 and don't try to hit 700 tops. My usual stove top temps are between 450 550 with lots of secondaries for 2 - 3 hours depending on the wood I am burning and how well loaded the stove is.
The original op I wonder about dry wood, I never open the ash pan to get the fire going and normally with a decent coal bed can restart with the door closed .
Thank god spring is here .

 

[begreen]

The stove was a bit undersized for our house so I had to push it a little harder in colder weather. That and doug fir can get intensely hot quickly with a little encouragement. During milder weather we ran it more around 500F with partial loads of fuel.

 

[Ski-Patroller]

I bought the 6" Duravent Double Wall pipe to connect to our 12' of 8" insulated flue. I'm going to try to install it this Saturday. I expect (hope) it will make a significant difference in the stove's operation especially at lower firing rates.

Our stove is big enough for the cabin once we get it warmed up, but when we walk in on Friday night and the temp inside is 30, we want heat now!! I wish I had two of them for the first few hours.

 

[Wade A.]

Ski Patroller....I've burned the F400 for 5 seasons now, and I do love it. I have it vented straight up, with a 16', 6" Class A chimney/double walled connector. I run about 3 cords a year, mostly oak and hickory. My experience has been just the opposite from yours: At times, the stove can run-away on you if you load a lot on top of a good coal bed. When I was just learning to use the stove, I more than once had to stuff a ball of tinfoil into the primary air opening (as mentioned, that is under the stove, at the rear. Crane your neck and you'll see it) I've also noticed the stove likes exremely well dried wood and performance drops off appreciably when you even get north of 12%... which is an outside the split reading I'm referring to. That might be 15% + on a fresh split/inside.

Larch and fir are some fast/hot burning woods, and I'm going to believe you when you say it is dry fuel. The only variable I'm thinking it might be is the wider pipe you are running. It sounds as if the secondary gasses are venting up your stack, rather than getting a chance to recirculate and burn. That is going to cut down on your burn temps, and diminish the stove's efficiency if true. I'd try a damper in your connector pipe, yeah, and see if you can choke that down any. That would be much quicker and cheaper fix than replacing stove or pipe, of course.

As for burn times, no, the size of the firebox makes it hard to keep a large, hot bed of coals going all night, let alone a secondary burn. Still, it can be done. In my book, if you come in the morning and are able to rake a pile of coals together, open your secondary air, throw on a couple of splits and get a flame after only a few blasts of the blow-pipe, well... that is an all-night burn to me!

And yeah, +1 more for not burning with the ash door open. It only takes one time.

 

[Ski-Patroller]

We got the new 6" Double wall installed this weekend. It does make a difference. I was surprised how much creosote there was in the 8" Single wall we took down. I know we have not been burning as hot as desired, and that sort of proved it. Our wood is in the 15% to 17% moisture range which may be part of the problem. There isn't much I can do about that this year. Even the Larch that has been in my basement for 1-1/2 years is about 15% and it was pretty dry when it came it. I may need to arranged more air circulation in the wood storage during the summer months. We are also splitting the wood a lot smaller than we did with our old Garrison stove.

We can see when the secondary air is working well, but it doesn't happen until the stove is up to 400-500 degrees on top. We try to run in the 600+ degs and it is much easier now. It seems to me that if you turn the stove down, near the bottom (far left) you never maintain enough temp for the secondary air to work properly.

I keep reading stories about these stoves running away. I can't imagine that happening with ours, but I guess I'd better be prepared for it. I don't want to deal with a chimney fire. I need to look at the stove next weekend to see if the bottom heat shield limits access to the air intake.

 

[Grisu]

Our wood is in the 15% to 17% moisture range which may be part of the problem. There isn't much I can do about that this year. Even the Larch that has been in my basement for 1-1/2 years is about 15% and it was pretty dry when it came it.

I am not sure what moisture levels you want to achieve but that is about optimal for a modern, EPA-stove. Depending on your relative air humidity you will not get it below ~13% anyway. For taking the moisture content, are you splitting a piece in half and measuring the center of the fresh surface the pins inserted along the grain?

 

[Ski-Patroller]

That is how i'm taking them. I'll look at the m% a little more, both at the cabin and at home.

 

[unhdsm]

Isn't this the stove that winds up behaving differently based on the configuration of the vent? When I did research before buying the Shelburne I remember the reviews were all either wonderful or horrible and it turned out that it was mostly based on which way it was setup.