Need more boiling in back pan

[Maplewalnut]

Can't find the old post that referenced this but what do I need to tweak to get better boiling at the back of my flue pan? Syrup pan and front of flue pan boiled like mad last season but seems like I lost boil the closer to smoke stack I got.

I start sloping my vermiculite about a foot from the stack, should I narrow the gap a little to keep the heat under the pan a little more? I need ever tweak out there this year!

[3rdgen.maple]

drop or raised flue? My drop flues just about sit on top of the brick maybe there is a 1/4 inch gap. Of course just in the back half as there is a ramp up to that point. My drop boils harder in the front and back than in the middle but does boil throughout. If you got a raised Im not the man for this question.

[brookledge]

With either a raised or drop flue you need to force the flame and heat through the flues. I you have a gap between the bottom of the flue and the arch that space will be flowing hot gasses that will never make contact with the pans and there for lost heat up ther stack.
Also do you keep the flues clean on the underside? Brush them regularlly. If they are built up with soot you will lose heat transfer.
And it could be your wood if it is wet or green it will reduce your boiling capacities
Keith

[mtnmeadowmplfarm]

If you are running a raised flue, try putting a baffle at the top of the ramp to help force the heat up through the flues.

[Russell Lampron]

I have the same evaporator as you and I put a blower on mine. Mine boils so hard at the back now that it boils in the float box too. I have the same spacing at the rear as you as well.

[Maplewalnut]

Sorry, it is a raised flue. Wood is dry, flues are clean. This started from day 1 so I am sure it is the way I set it up. My vermiculite is just below my rails-maybe I need to close that space a little


I have a blower now but I think I can upsize it a bit.
Russ-is your blower positioned under the rig or in the front of the damper.


Wouldn't a baffle keep more heat under the syrup pan?

[Russell Lampron]

Maplewalnut,

My blower is positioned behind the firebox. I have a baffle that directs the air up under the grates and a damper so that I can control the air flow. When I have it going just right I can fire it without shutting off the blower and can see flames in the space between the flue pan and stack base.

[Brent]

This makes for an interesting trade off. If you boil all the way to the back then you have to pumping a lot of hot air up the stack.

If you're only boiling near the front, then I think you would be more efficient.
Won't boil so many gallons per hour but also won't burn so many logs per hour.

Trade off is, do you have more time or more firewood.

If you haven't read it yet, go through this article on evaporator efficiency by the US Forestry Dept

http://www.duffyslanemaple.ca/Making-syrup/preheater%20study.pdf