stack temp

[jemsklein]

I have a homemade rig 2'x10' and the first boil with out the blower gave me a stack temp of 180F. So I put the blower on and the stack temp shot up to 220F but everything boils good even the back pan so why is my stack temp so low?
I know that every one else gets like 700F.

[WESTVIRGINIAMAPLER]

I would guess the draft is not pulling the heat up the stack like most evaporators. If it is working good and boiling good, then that is what matters most. Sounds like your stack thermometer may be bad as I can't imagine the back pan is boiling good with that kind of stack temp. Also, most on here that are talking about stack temps have a hole drilled in their stack with a probe inside the stack. If you have one mounted on the outside of the stack only, it will be a lot lower.

[jemsklein]

Well my old evaporator it got to 700F on the stack not in it and this one I can go up to it a touch it and it don't burn you.

[mapleack]

How many feet tall is your smokestack? You may need as much as 3 times the length of the evaporator to see the best draft. I've got 30 ft on my 3x10 and run about 620 deg on the surface of the stack.
-Andy

[jemsklein]

i got about 11 feet of stack

[tyrod2]

I would like to find out what my stack temp is .What kind of thermometer do I need and where would I get one? Thank You

[jemsklein]

I just used a normal thermometer cuz our stack temp is so low.

[WESTVIRGINIAMAPLER]

They recommend 2' of stack for every 1' of evaporator length.

[syrupmaker]

Most stove shops have the stack therms, usually found in the 3" dia. range with a yellow/orange/red scale. Our temps this year have been running 7-900 degrees depending on who is fireing and how high you turn up the berrieis on the blower. Night time is cool, looks like a jet eng. at idle.

[mapleack]

Jemsklein, you definately need more stack than 11'. A blower will make a fire burn hotter, but you stil have to have a good draft to pull it back through. I'd at least double what you've got, if not more, and put guy wires on it if necessary. You'll be pleasantly surprised with the results.
-Andy

[jemsklein]

ok i will try a 20' tall stack and let you know later

[Brent]

while your looking for the extra stack, I think you should get a new thermometer. I don't think the reading you're reporting can be correct, unless you're using a surface mount magnetic one without a probe that goes into the flue gas, and it's the flue gas you want to compare with what others are reporting.

I got brave last night and went about 1 1/2 hours to 1000 degrees. With aggressive wood loading I think I might get it to 1200. Might need the blower and or more stack to get higher. Roof clearance is not so good so 3' more stack is coming anyway.

[jemsklein]

well i put 3 more feet of stack on and it brought the temp from 220 to 420 F

[mapleack]

That temperature increase should result in a nice GPH increase for you! I'd add at least one more joint of pipe, maybe two and you'll see a similar increase and really be boiling!