Ash Door

[mike z]

We got an arch front for the evaporator we are building, it did not have any doors though. For the ash door, is it really necessary to have it adjustable, or would it be open all the way when boiling to let air in? No blower planned. Also, my dad insists on putting a damper in the stack? Is this necessary? Thanks for the help, we're almost ready for the firebrick.

[brookledge]

I would not worry about having the ash pit adjustable. You want to make sure that the grates get good cool air to them from the underside. If you close off the air to much it will cause the grates to get to hot and can warp. As long as the opening is not overly sized you could leave it open and then close it off after shutting down.
As for the damper I'm not sure what size evaporator you have but in most cases it will not be necesary to use a damper. The evapoator is not like a wood stove that wants to have the draft slowed down. Slow the fire down to much and the pans will just simmer you need to keep the fire ripping. It make a better boil. i'd say you should be looking for a stack temp in the 1000to 1200 range. An evaporator is like a car put the petal to the floor and you will go fast but use more fuel. Well you need to decide how you want to run the evaporator. fast and furious with no damper to get maximum evaporation while burning a little more wood or slow it down and boil a little slower
keith

[Thompson's Tree Farm]

No damper in the stack. As Brookledge says,you want it rip roaring. On my 4x12, the ash pit door has been removed. It is in the way when I clean out the ashes and I can barely remember a time that we adjusted the draft (and I have been doing this 50+ years).
Doug

[maple flats]

Absolutely no damper in the stack. Evaporators need max air flow, you never want to slow it down. For the adjustability on the ash door, before I had high pressure air over and under the fire, I did some adjusting. It was just when starting the fire and within 15-20 min the door was full open. If you want this, just get a brick to prop the door up with. When lighting have brick flat, as soon as a good burn starts, lift door and stand brick on edge and when fully burning, prop door fully open.

[mike z]

I better get over to Dad's shed and stop him before it's too late. Everytime I go out there he's got something new added or cut off. It's been a lot of fun though. Thanks for the help.