Steam hood ?

[arcticair]

I just built a stainless hood for my 30" x 48" drop flue pan . The flues are 7" deep and have 7 of them . my question is do I vent the hood from the bottom edge or space it above the pan and what diameter for the venting . I am also adding a preheater in the hood once I figure out the pipe sizing , any help would sure be welcome .

[Sugarmaker]

No venting required where the hood sets on the pan. It will suck air in around the general fit of the hood to the pan. This will keep some heat in the hood for your preheater to work which will improve your evaporation rate about 10% and also give you several gallons of hot condensate water per hour. lets see a picture of your hood.
If your asking about the size of the steam stack I would go with at least 8 inch and/or 10 inch would be OK too. I have 10 inch steam stack on a 3 x 5 rear pan.
Regards,
Chris

[arcticair]

My steam hood fits snug around the top of the pan , so no venting around the hood is required , I dought much air will get through . I know I need a condensate gutter inside for the condensation and one for the preheater . We just built the 7 inch drop flue pan and hood and realized that the hood is snug ( the plastic wrap on the stainless is the only play we have when we peel it off )

[arcticair]

Will post some pictures when I get out of the bush tomorrow .

[arcticair]

10937As you can see it fits snug , still have to add the access door and the condensate gutters , will I need the venting in between the hood and pan . Sorry 3rd photo is upside down . 109351093610934

[arcticair]

Just an update on the pan , no hood / no preheater average 52 imp gallons per hr . Now if I can get the preheater and hood finished in enough time for next year hoping for 70 gallons / hr.

[BreezyHill]

mine is 6" pipe off a 2x4' flue pan and preheats in a wooden box that houses a 1.5" SS sap supply pipe. Comes of right over the float box inlet to that the heat sap stays in the steam flow as much as possible. Total distances: +- 3' to the wall and another r 8' along the wall. boiling faster last season and was only getting preheated to 180 on average. Season before I had a Chicago fan pulling the steam out and she was running 190-195.
11808

[Pibster]

Just an update on the pan , no hood / no preheater average 52 imp gallons per hr . Now if I can get the preheater and hood finished in enough time for next year hoping for 70 gallons / hr.
The preheater will at best give you a 10% boost, but not the 35% you're hoping for. Still, it's worth having one for the extra 5 gallons and the hot condensate water.

[maple flats]

I don't see a gutter around the inside with a drain to the outside. I hope I'm just missing it. The hood and stack will sweat down the inside and it you let that go back into the flue pan you then need to evaporate it again.
On my homemade hoods I used 1" aluminum channel made in 1/8" thick aluminum, then I mitered the corners, used aluminum "welding rod" which is used like a solder. It is available at TSC. Then I drilled and tapped a hole in the outer edge and fitted a drain. Actually 1 was tapped and another I built a channel extension out 1 corner. Then I just set the hood into the gutter and pop riveted them together. The gutter channel was to the inside. Another thing, you want to make a catch funnel under the steam stack to catch drips and then send them to the gutter too.
On my factory hood for my 3x5 flue pan and my 3x3 sap pan, each has a gutter that is 1.5" wide. There is a 3/4" half coupling welded at each corner facing outward so I can run my condensate any direction. I have a 3/4 male adapter screwed into one front coupling on the syrup hood (this hood is attached to the flue pan hood at 16" higher at the bottom) then a copper tube runs from there to a fitting into the flues hood on the same side. From there all condensate runs to the rear corner, where it drains out thru that coupling and into a bucket. Also, each hood has a 15" steam stack (bigger than needed? This is factory made) Under each stack is a wide shallow funnel to collect that condensate and it is then channeled to the side gutters. When I had a 3x6 flue pan with homemade hood the channels were just 1x1x1 and the stacks were 12", now on this one the channels are 1.5 x 1.5 and the stacks are 15". On the 3x5 flue pan hood stack I have a damper that can be locked in position, restricting the steam flow, for best performance with a pre heater, the syrup hood stack has no damper.

[MT Pockets Producer]

We run an 8 inch stack on our 2'X4' back pan which is the same on the commercially sold units that size. Maple Flats suggestion of gutters and catch funnels are a must if you don't want to re-boil your condensate. These are photos of our hood and pre-heater. The gutter around the sides are 1.5 inches and drain out in the corner where you can see the lowest fitting in the photo. That is collected in a bucket and is great for wash water in the shack. The tray under the preheater catches both the condensate from that and the stack and then slopes to the end gutter and drains from there. As far as the pre-heater goes itself, this was what we came up with that works for us. The more pipe you can squeeze in there the better off you will be. This gives us 180 degree plus sap as it enters the float box. This is a manifold style set up on each end using Ts and elbows and is fed from the middle fitting you see entering the hood pushing the sap up and out the pipe on the top. Your head tank needs to be higher than this to push that through. The manifold allows the sap to flow through the system by taking the path of least resistance if any of the pipes get air bound. The incline in the system allows the air to seek the highest point and push out ahead of the sap. It is not in the photo but once we set this up and used it we added a vent tube that comes off the top pipe after it leaves the hood. It was getting air bound because the float that lets the sap into the evaporator is at a level 1180911810lower than this pipe. Keep in mind that your vent will have to terminate at a point higher than your head tank or sap will flow out of it. The pipe size is 3/4 inch. Also, the hood sits down tight to the pan, no air space. The legs you see on it just keep it from shifting once it's in place.

[arcticair]

Sorry , I knew I needed the gutters and drain pan under the exhaust pipe . Just wasn't sure if I required spacing around the hood and pan . I make Birch Syrup and have to use all stainless , copper piping only gives the syrup a metallic taste due to the acid in the sap .