Understanding how the hood n preheater work

[bnbmaplesyrup]

We are very new to this. We have been cooking on a cement block arch out side last 2 years.We have moved into a enclosed building. We have a 2X6 flat pan and have built a new arch to fit it. We have been thinking about building a hood n preheater for it. I have a few questions on how this works.
1. will a hood work on a flat pan that we run batches of about 3 gallon syrup at a time
2. Does the hood need to cover the whole pan
3. Do you need an exhaust fan for removing steam up an out the stack
4. Where do I find the plans to build something like this
Thanks in advance for all your help. I have found this site to extremely helpfull

Bill

[maple flats]

If you cover the whole pan, how will you monitor what is happening in the pan. For a hood and preheater to work, they are generally set directly on the rear pan. No fan is needed to get the steam out, in fact a damper is often used to hold steam in the hood to raise the temp as high as possible. The damper is regulated so just a very little escapes the hood out seams, doors and the mating surface of hood to pan.
I'm not sure how much benefit a partial hood on a single pan would help, but it will help some. In the future, if you grow and get a 2 pan set up, put a tight fit hood and pre heater on the rear pan.

[Hop Kiln Road]

http://cdi.uvm.edu/collections/getCollection.xql?pid=maple&rows=1&start=0&fq=creator_facet%3A(%22Duchacek%2C%20Howard%22)

[bnbmaplesyrup]

Bruce Thanks for the website with the plans.

Dave I was planning to put a door in the side that I can peek into and keep monitoring it that way. Does anybody else do that? Do you lose too much pressure from opening the door often?

Thanks Bill

[lpakiz]

Bill, I thought of building a temp hood out of plywood ends cut to contour and aluminum or 28 ga. Galvanized. You would need a flat top to accommodate the stack. I was looking at some old wooden 24 inch stop signs I have. Just cut one in half horizontally and the ends are done. My local steel supplier has sheets of metal. 28 ga is quite reasonable.

[wiam]

Bruce Thanks for the website with the plans.

Dave I was planning to put a door in the side that I can peek into and keep monitoring it that way. Does anybody else do that? Do you lose too much pressure from opening the door often?

Thanks Bill

As soon as you open the door you will get a blast of steam, then you won't see much in there.

[Pibster]

Why are the manifolds usually a larger size pipe? I had planned on using 3/4" pipe for my manifolds with 1/2" pipe in between, but would all 3/4" pipe work as well. Maybe the larger manifold helps distribute the cold sap evenly? My hood is only 24"x 36".

[Maplebrook]

The manifold needs to be sized large enough to feed your evaporator. You want the preheater pipe (between the inlet and outlet manifold) to be small(er) for better heat transfer. The area of a 3/4" circle is equal to 2.25 half inch circles. (Think inside of copper pipe here) If you build your preheater with 3/4" manifolds and three 1/2" parallel pipes, you will not starve the evaporator and have max heat transfer.