Jotul 602 B . . . 5" or 6" Pipe?

[Woodward Stovenstein III]

Hi folks.

I recently picked up a well maintained Jotul 602 B and have been pondering my strategy for installation. This is a venerable workhorse of a stove, and I desire to operate it as efficiently as possible on seasoned wood.

I will be running pipe straight through the roof from the top smoke outlet.

My question is this: In order to maximize the efficiency of my burns should I run 5" pipe?

This Norwegian stove was built with a 125mm smoke outlet, and was shipped to the US with a 125mm to 6" adapter. From what I've read, the only reason the stove shipped with a 6" adapter is because that's the more common pipe size here in the US. In Europe, they run 125mm on this stove.

I have the 6" adapter on my stove already, but it is very, very easy for me to purchase the 125mm to 5" adapter from Elmer's. And as for 5" pipe, both Duratech and Selkirk sell what I need.

Will running 5" pipe give me longer, hotter, and more controllable burns?

I know what the manual says, so don't quote it to me. I'd like to understand the physics of this scenario.

Here's what I think. I think I would be better off running 5" pipe, because it is best to run as small as possible without going smaller than the smoke outlet. I'll get the best draft and thereby gain more control via the door damper and a flue damper.

Let me know what you think. This sight is chock full of wisdom, and I look forward to hearing from you.

 

[bholler]

I would run 6" it will leave your options open in the future.

 

[Woodward Stovenstein III]

Yes, that's the one downside I see to running 5" pipe. But let's suppose I have access to an unlimited supply of older Jotul 602's and the obsolescence of my 5" pipe never becomes a factor . . . Will I have stronger draft and a greater range of control over my fires, including regulation of heat output and burn time?

 

[huauqui]

I am no expert on draft but I do know this, stronger draft often times means less control over fires, especially when you want to burn low and slow.

huauqui

 

[begreen]

USA Jotul 602s that I have owned came with a 5" -> 6" adapter. 6" pipe is all I have run for them.

 

[Woodward Stovenstein III]

Suppose I want to run a shorter stack, somewhere in the range of 8 ft from stove to cap. Would running 5" help to ensure that I get good pull? Or does 1" not make a difference?

 

[Squirrel]

The Morso 1410 runs on a 120mm (4.7") chimney in it's native Denmark. Mine is on 20' of 6" chimney but the outlet on top of the stove is 5". I have full control of the stove, even with a draft that will suck up unsuspecting passersby.
I do think that a 5" chimney would stay warmer at the top end as I know that in really cold weather mine can cool too much with the stove turned down.

 

[begreen]

Suppose I want to run a shorter stack, somewhere in the range of 8 ft from stove to cap. Would running 5" help to ensure that I get good pull? Or does 1" not make a difference?

I have our 602 on 10ft of straight up, 6" stack and it is draws ok. That is with 6' of double-wall stove pipe and 4' of chimney.

 

[Woodward Stovenstein III]

I called a dealer in my area and he shared with me a piece of knowledge that makes my decision much easier. He told me that when Jotul started shipping the 602 to the States with the 125mm to 6" adapter, he's fairly certain they made an internal modification to go along with the 9.16 square inch cross sectional area increase that the adapter creates.

If that's the case then I certainly ought to run 6" pipe. Also, I probably ought to run 6" pipe because Jotul tells me to in the manual. But I like to know the whys of things.

Thanks for confirming that a Jotul with a 6" short stack will draw well. I'll install a damper and burn seasoned wood. If you have any other tips for me to burn efficiently with this champ of a stove let me know.

 

[begreen]

Be mindful of the stove temp. With dry wood, this stove lights up and takes off quickly. Once it is going well close the air down all the way and then open it up just a hair. A small adjustment in the opening can make a large difference. Keep a thermometer on the stove top to learn how it reacts and try to keep it under 700F.

 

[jetsam]

Install 6" pipe. If you want to restict it, I bet you could put a 6" to 5" adapter at the top, and clamp the cap to the adapter.

That way when you want a 6" flue, you have to pop the adapter off and you're done. Much easier than running a new liner.

You would need to take the adapter off every time you sweep, but that's not much more work than taking the cap off.

Disclaimer: I'm no chimney expert!

 

[begreen]

The 120mm to 150mm adapter goes in the flue collar on the stove. Everything from that point is 6".

 

[Woodward Stovenstein III]

Excellent! Thanks, begreen. Should I put sand at the bottom of the stove?

 

[begreen]

I put about 1/2" of sand in the bottom of the stove when I rebuilt our stove and leave a layer of ash on the bottom when cleaning.