How many CFM should I be looking for in a AUF/AOF modification to my barrel stove evaporator?
How many CFM should I be looking for in a AUF/AOF modification to my barrel stove evaporator?
Almost any additional air for AUF in a small evaporator like that will make a difference in evaporation rate. I would look for a cheap 200CFM (or more) squirrel cage blower and put a damper on the inlet to the blower to fine tune it. Too much air and the fire is really putting out the heat but it blows right past the pans with the high velocities and you end up with high stack temps and wasted wood.
I think it will be difficult to see any advantage of a high pressure AOF system on a short system like a barrel. Save the time, complications and money for when you have at least a 2x6.
John
2x8 Smokylake drop flue with AOF/ AUF
180 taps on sacks
75 on 3/16 tubing with shurflo
Eden Prairie, Minnesota
Ok so anything is better than nothing in a AUF modification. I currently build the fire on the sand in the bottom of the barrel. Will I need to put in a grate to get the fire up off of the sand so the AUF can get under the fire better?
Raising it up is a good idea even if you do not use AUF.
What is recommended for a grate so it is not effected by the heat?
A lot of people use 1/4" angle iron in this configuration VVVVV. Ashes build up in the V and keeps them cooler so they don't deform
2013 135 Taps 35 on Gravity, 100 on Buckets 11 Gallons Made
2014 310 Taps 75 on Sureflo 4048, 235 on Buckets, 16'x16' Sugarshack, 5" Filter Press, 2x6 Smoky Lake Hybrid Pan (SOLD) 23 Gallons made
2015 315 Taps, 17 on Sureflo 4008, 62 on Sureflo 4048, 236 on Buckets 31.25 Gallons Made
2016 New Northwoods Stainless Finisher and Steamhood
2017 325 Taps 34 Gallons Made
2018 150 Taps New Northwoods Stainless 2x6 Raised Flue w/ Air Tight Arch 40+ Gallons Made
2016: Homemade arch from old wood stove; 2 steam tray pans; 6 taps; 1.1 gal
2017: Same setup. 15 taps; 4.5 gal
2018: Same setup. Limited time. 12 taps and short season; 2.2 gal
2019: Very limited time. 7 taps and a short season; 1.8 gals
2020: New Mason 2x3 XL halfway through season; 9 taps 2 gals
2021: Same 2x3, 18 taps, 4.5 gals
2022: 23 taps, 5.9 gals
2023: 23 taps. Added AUF, 13.2 gals
2024: 17 taps, 5.3 gals
All on buckets
Thanks everyone! I guess I better get to work
You definitely want a grate. Beneath that is the " under" of AUF, so that is where you introduce the blower air. I use the inverted steel angle mentioned here. It works well. Mine have gaps of about 1/4 to 3/8 inch between angles. The area under the grate needs to be closed off so all the air goes up through the wood. many, including me) block off the very front of the grate near the door so the airflow can't short cut past the wood in that area and to keep the door cooler.
Depending on your stack and the draft it creates, you may need to throttle the blower to keep ash from blowing out the gaps around your arch. Else you need to seal things up well.
John
2x8 Smokylake drop flue with AOF/ AUF
180 taps on sacks
75 on 3/16 tubing with shurflo
Eden Prairie, Minnesota
I used a small bathroom vent fan for AUF. It uses a 3" vent pipe. I plan to add a variable speed fan control to it this year. Previously I had just blocked part of the inlet.
I used a BBQ grate for the grate. You can pick up replacement ones at home depot, etc. There is some drooping but I flip it over every batch so it's not an issue. They last a couple years.
2015 - 8 buckets, 332L sap, 8.5L syrup - Barrel evaporator, 2 steam pans
2016 - 8 buckets, 432L sap
2017 - 10 bags, 470L sap, 9L syrup
2018 - 20 bags, 1050L sap, 17.6L syrup
2019 - 20 bags, 970L sap, 22.2L syrup
2020 - 17 bags, 813L sap, 17L syrup