Stack temps

[mapleman3]

Just curious what everyone is running for stack temps... I have oil and have been able to drop my stack temp from 650deg to 525deg this years from redoing the insulation under the sap pan and how it goes into the stack area... resulting in more heat staying under the pan... I know wood is totally different and the stack temps are real high.. so curious what you oil guys are getting.. wood guys feel free to add your temps too. also what nozzel sizes for evap size .. could end up a good thread for guys converting


I'm at 3gph for a 2x6 @ 525deg stack

[davey]

This is actually something I'd like to hear more about too. I converted a 2 1/2 x 8 to oil and am currently running a 4 gph nozzle but my stack temp is way too low, around 250. I ordered a 4.75 nozzle and will stick that in as soon as it comes. I'd like to go as big as I can but not many around here carry those kind of nozzles. thanks to any and all for your input.

[325abn]

On my 2X4 I am running a 2 gal/hr with a stack temp about 630 - 650 .

[maplwrks]

Here We Go----my 2 1/2 X 8 Came With A 5.5 Gph Nozzle In It. I Used It For The First Year That Way. The Evaporator Boiled Real Hard, But Stack Temps Were 1100 Degrees. I Have Since Cut It Back To 4.5 Gph And Dropped The Stack Temp To 700 Degrees. I Also Put A Damper Into My Rig To Try To Keep The Heat Under The Pans. I Preferred The Boil I Got With The 5.5 But Can't Afford The Fuel!! It Is My Plan To Convert To Uvo For Next Year And Go Back To The 5.5 Gph Nozzle

[325abn]

What is Uvo? Used veggie oil?

[danno]

Good topic - if your evaporation rate is good, do you want a hotter or cooler stack? Does hotter mean your evaporation rate will get better or does it mean that you are just wasting heat up the stack?

I had some questions when I saw posts on this issue in another thread. I'm a wood burner and seem to max out at 600 - which seems lower then allot of wood burners. My evaporartion rate is ok (about 90 gph on a 3x10 with 7' flue pan, 7" deep), but I know I can do better. I moved my forced air fan about 20' from where in enters the arch and I think the cfm's are down.

I've got a 14" x 20' stack so I get great draw, and the stack size probably keeps the stack a little cooler. I have so much draft that I don't know if there is a fan big enough to blow smoke and ash out the front of the arch.

[maplwrks]

Uvo---used Vegetable Oil

[Homestead Maple]

3x8 King evaporator with a 5.5gph nozzle and stack temp is 800-825

[Grade "A"]

I have a 2x5 flat bottom pan and run a 2 gph nozzle with 600deg stack temp. I would put in a bigger nozzle but my burner can't put enough air in with the fuel to burn good. I would think that if you can lower your stack temp with out changing anything with burner means your keeping more heat under your pans.

[mapleman3]

you don't want to waste the heat up the chimney, on a boiler you want the most heat exchange.. but also have to be careful not to burn the pans up too

a barometric damper on the flue lets air into the stack above the evaporator to keep the draft over the fire down to keep the flame in place and not pull it away from the burner or suck the heat out of the evap. thats the flappy thing you see on a boiler chimney.

[sapman]

On my 2.5 x 8, I used to run 600deg. on a 3.5 nozzle, so burning 4.5 gph at 150 psi. I've since bumped up to a 5.0 nozzle, so about 6gph, and stack temps usually around 1000. Now with the RO, I think I'll throttle back down a little, to maybe a 4.5 nozzle, and probably be a little more efficient.

Tim