Hood & Preheater

[Dennis H.]

I am looking at several things to increase my gph evap rate for next year, one is to get a bigger evap!

I was tossing around the idea of making a hood with a parrallel preheater inside. The question with this setup is does it really need to be tight to the pan?

When I was doing some research what I found was that the parrallel preheater and hood should be a reasonably tight to the pan.
So if the pan, preheater and hood is a tight fit then how do you get a good draft so the steam will go up and out the steam stack? I would think that you would need some means of etting air in at the pan to generate a draft.

[Haynes Forest Products]

We are not talking about a wood stove. What we have when we put a tight fitting hood over the evaporator is a steam boiler. If you were to put a small propeller over the steam stack and it turned then you would have a steam engine. VERY LOW TECH but a steam engine just the same. You dont want air to enter the steam vessal because it will cool things down and cause the steam to slow down. Im not in any way suggesting this but if you were to make the fluepan and hood air tight and restrict the steam flow so as to increase the internal heat you would get more steam generated and that would speed up the prosess. So my vote is for a nice tight hood.

[lpakiz]

I agree with Haynes..you are boiling (water) which expands as it turns to vapor. No make-up air is needed--it is generating its own "volume' to force itself up the steam stack.

[Bradenfish]

I have a 3x10 with a 3x10 hood on it thats not airtite but all the steam goes rite out the 16'' stack.

[Sugarmaker]

I also built a semi-tight steam hood for our 3 x 10 back pan. It does draw air into the hood through the seams and doors, and when I close the damper too much I get steam coming out all those same cracks. Not a big deal and seems to work just fine getting the sap in the parallel flow preheater to 200 deg F which is about all you can expect. not sure of the efficiency but maybe 5=10 %??

Regards,
Chris

[Daryl]

I just bought a 18 x 63 Sportsman D&G. The flue pan is 45" long. How many feet of what size copper pipe should I use. It will have a tight fit hood and a damper in the stack. I'm going to have air injected over the fire and a blower with air up thru the bricks for grates. With this kind of a setup, what number of taps would be a good number to run without killing ones self?
Daryl

[Sugarmaker]

Daryl,
How are the hoods coming along?
I am making two hoods for Keith Talbot right now. Hope to have them done before the holidays.
Try to get 8 or 10 (3/4 dia) copper pipes at 42 inches long should do the trick. 200 taps seems like it would be about the limit unless you have help to boil around the clock.

Regards,
Chris

[Gary R]

Hi Daryl,

I agree with Chris, as long as they can be and as many wide as you can fit.

[sweetvt]

Several years ago I had a D&G sportmans model and ran a 150 taps on it. When the sap ran I put in some long days and nights. That would be the max I would ever do with that set up. Now I have a Lapierre 18 X 66 (very smiliar to sportsman) and I have it set up with a steam hood and preheater in it as well as forced draft. My preheater has 6 lengths of 3/4 " copper tubes inside the hood. I probably might have gotten one more put the drip pan would have then covered all of the flue and was concerned about stream vent issues. Under optimal conditions (very dry wood, good sugar content etc) I can get at best 20 ish gals per hour evaporation from mine. Perhaps injecting air over the fire as you plan would boost that number.

I would think 150 taps would give you all you would want, but if you have lots of time then the skys the limit!

[Daryl]

Thanks for the imput. I think I will try for 9 or 10 pipes. Next is to build the hood to fit. Too many ideas and not enough time.
Daryl

[Sugarmaker]

Daryl,
That's my problem too. I did get the ends of Keith's hoods whittled out today. No bends on those yet. He is going to use 1/8 inch sst pop rivets to fasten it all together at the seams. Then get the lower corners welded for the drip edge on the inside of the hoods. We will be using 8 inch diameter steam pipe and the front hood vent pipe will tie in to a tee just above the damper in the back hood.

Regards,
Chris C.