Base stack-how hot is too hot?

[ebliese]

I've got a question about base stack temperatures. I tried to do some research here but most people are talking about stack temperature in general. My questions are a bit more specific. This might be a dumb question, but I'm learning here. How hot is too hot for the base stack? If it starts to get cherry red? I've noticed my base stack can get a cherry red color so then I adjust the draft door to compensate. Our stack is 12 feet tall. I only have the draft door open fully when I am starting up the boil. I do not have a way to monitor stack temperature (other than eyesight). Just trying to get the hang of running this rig in a safe, efficient way. We had our third boil last night and it came with some excitement! Almost burnt the draw-off channel. Had to flood the pan. Our main mistake was starting with too low a level in the pan to begin with.

[ir3333]

Depends on how efficient your arch is. It should transfer most of it's heat to your fluid before it gets to the flue.
A cherry red stack may be over 900 degrees.I think a good boil with a stack temperature of 600- 700 would
be very efficient and save a lot of wood!

[buckeye gold]

your drawing too much heat away from your pan, I believe. Maybe shorten your stack and reduce the draw .

[johnallin]

A 2x4 rig shouldn't need much more than 8' of stack. Buy a stack thermometer from a local stove shop or hardware store, about $30 max and try to keep temps in the 5-800° range you should be good.
That stainless stack will eventually turn purple from the heat, no harm in it, it's just what happens.
Have fun with that new rig

[ebliese]

To answer some questions:

Our arch is an air-tight one from Smoky Lake.

I re-examined our stack and it turns out I could shorten it by taking a 2' section off and still be in accord with the 3-2-10 rule. So now the stack is 10' tall. I can't go lower than that unless I were to cut a section of pipe in half. Shortening the stack did seem to help the problem some. We still, on occasion, got to a dull red color on part of the base stack. I was running the arch with the draft door mostly closed. I was not running on a timed firebox reload but mostly going by the look (looking through the sight glass on our arch).

A stack thermometer sounds like a good idea. I'll take a look around for one.

[woodguyrob]

There's a great video from Smoky Lake running the Corsair illustrating it's GPH potential. It was done inside the show room so presumably a tall stack. It never appeared that they had a blazing hot stock base. If you call / email Jimi, Jim or Matt at smoky lake they can advise.
SmokyLake Corsair video https://youtu.be/HQPYXBiGheM

[berkshires]

What is the 3 2 10 rule? I have a new 2 x 3 evaporator, with 6' of 6" flue pipe (not counting a horizontal section to clear the shack.) Does that fit the rule or do I need to add more?

GO

[tcross]

i'm not sure of what the rule is, but i've always been told to have the stack at least twice the length of your arch. mine is about 3' taller than my arch due to getting it above the roof line... works great.

[n8hutch]

3-2-10 rule is your stack height to combustibles,as in when it comes up through your roof.

[berkshires]

3-2-10 rule is your stack height to combustibles,as in when it comes up through your roof.

Got it, thanks!

GO