AUF blower

[Millsy]

My son and I are building a new 2X4 arch for this season and want to incorporate AUF. I have a power vent blower from a furnace, would that work? Is that too much air or not enough.
Thanks

[maple flats]

It should be good. Put a damper in so you can control it as needed. A damper on the inlet to the blower is best, just design a way to lock the damper from moving when you set it.

[BreezyHill]

I now use an exhaust fan for large diesel engines for shops or firehouses. It is way more than what I need for my 2x6 but it taught me I don't need AOF when I can turn the Speed control up...using a heavy duty fan speed controller.

I do need to make a better grate than those that came with the evaporator. I have cracked 2 out of 3 grates due to them getting red hot.

The fan was hooked to a 8" reel of connector hose for truck exhaust stacks.

[deckers007]

I am using 2 gas hot water heater vent fans, they are relatively quiet and do not use that much power, i have had them on a normal dimmer switch to fine tune the speed. been working great for me for the last 3 years.

[craig1bc]

If you are going to be installing a new blower fan for a AUF what is the recommended CFM for a fan? I know there are a ton of options but plan on buying the fan new and want to get the correct CFM to optimize the burn rate.

[bowhunter]

See Dave Klish's comments on this thread. It's very important to control the flow. Too much air maybe worse than not enough. It can damage the arch and blow smoke and ashes into the sugar house and syrup. So either use an inlet damper which you can make out of a piece of flashing or a rheostat to control the motor speed. I have a small evaporator and I bought a new blower before last season. It's about 150 cfm which is too much for my evaporator. That size should be enough for a 2 x 4. You put enough air into the evaporator so that you get a good roaring fire but not enough to blow ash and smoke out around the ash door and the pan.

[Tom_saw]

I scrapped a Jenaire cooktop and used the exhaust blower for my 2x6 . It is a 5" blower .