Stack temp?

[Woodsrover]

Fired my 2x3 Mason arch for the first time tonight. Was running a 500+ degree stack temperature. I've heated the house with wood for years and always tried to keep my stack between 300-400 degrees so this hot stack has me wondering. What do you all tend to run for a stack temp?

[TerryEspo]

My stack is temp is over 500 also on the arch, not my inside stove tho. Just like you. Your fine. I can sometimes pin the thermometer on my arch stack at over 900 degrees if I try to. I think the ideal stack temp is around 700 degrees. Please someone post the perfect stack temp for our arches. Outside with the arch we are NOT trying to save heat. Outside we are looking for the BOIL, so let'er rip.

Hope that helps.

Terry

[Urban Sugarmaker]

On my Mason 2x4 I have to run a stack temp of 1100-1200 with the blower running to get a vigorous boil. Above 1300 and I get nervous and slow it down. Above 1350 the chimney cap/spark arrestor starts to glow (not safe, and wasting fuel). Unless my thermocouple is way off, I think you are fine if you are getting the boil you want. At 1" sap depth, small to medium fire, plenty of air, and frequent small firings, I get the most consistent boil with temps that usually don't exceed 1200F. Of course there are many variables such as wood moisture content, species, technique, etc.

I think the problem with these smaller rigs is that they are so short that the flat pan doesn't have much chance to absorb the energy. These small setups are great, but
you can only do so much. Although, I agree with Terry, let 'er rip if you can. I can't blast it due to my concerns over fire risk. Despite that, I can consistently average 10 GPH including startup/shutdown, which is right in the middle of my evaporator's rated performance. Can't complain.

[adk1]

Just remember that an evap isn't run like a house stove. U want it as hot as possible

[WI Sugarpop]

I have AUF and AOF and I run it at 750 to 850 by adjusting the air flow.That is internal stack temp.

[RC Maple]

I too have a 2x3 pan on a barrel stove. I have a magnetic stack thermometer on my 6" stack. For me, I have a good boil going when I am above 500 degrees, as the temp comes down to that level I am firing again. If it gets down below 500 I can tell it by looking at the boil in the pan.

[Woodsrover]

Boiled for about 5 hours last night and tried to keep the stack between 650-700 degrees. Seemed to boil very well at that temp. Thanks for your help...Those temps would have scared me had I not asked here.

[maple flats]

try 700-800 and the boil will be even better. This is why you will never get a chimney fire on a properly run evaporator. Creosote is formed when the stack is kept too low, but the wood fired evaporator runs so hot it will not form, you just get a light ash film at the most, which self cleans from the heat and fast flow thru the stack.
All this being said, be sure the roof (if you are firing inside) is properly protected. You need any of these: 3'+ to nearest wood, insulation, either rock wool or ceramic that is properly installed, or layers of tin or other non combustibles, each layer of tin spaced 1" on non combustables cut the space needed in half, thus 1 layer reduces 3' to 18", 2 layers each spaced an inch (or more) reduces it to 9" and 3 gets it to 4.5" clearance requirement. Each of these layers must be spaced 1" or more from the previous layer on non combustible spacers.
If you are outside with no roof, just attach 3 or more guy wires to hold the stack upright and enjoy. Someday you will move inside at which time you will need the protection of one of these.
By the way, before I added AOF (high pressure air over fire, I sometimes had stack temperatures of 1200-even 1400 degrees) , now it runs in the 550-700 range.

[Woodsrover]

I have single-wall chimney up to a support at the rafter ties and then three-wall Duravent thru the roof and above. The roof is metal.

Related, I was surprised how long the arch "flywheeled" after I stopped adding wood and started to plan on heading in for the night.

[maple marc]

My Leader 2x6 WSE runs best at about 900 degrees as measured by a probe at about eye height in the stack. From my experience it is very easy with a short evaporator to overheat. I started on a 2x4 and I was told to run with the draft door open wide. Well, without a thermometer I soon realized that my stack and door were glowing red and sap was spitting out all over the place. Sap flow was a mess too. After I added a thermometer I realized I had been running over 1600 degrees! Now with the 2x6 I watch the temps carefully and adjust the draft door and the size of the wood I feed. Wood size and species makes a big difference. By maintaining a good constant temperature I find that my flow and draw in the syrup pan is much more even. Every evaporator size probably has it's own "sweet spot" temp. You will find it will experience.
Marc

[PA TAPPER]

I normally maintain the fire with a internal stack temp between 700 and 850 on my 2x6 hybrid . Works well for me !

[eustis22]

Does anyone have a recc'd stack thermometer? Mine is out of whack as it's showing my 2X3 +1000 degrees.