Float box and preheater

[Pibster]

I am planning to build a steam hood and a copper parallel preheater this winter. Is a float box a must or can I just control the flow into the preheater with a gate valve? I have no idea how to build a working float box.

[Greenwich Maple Man]

The float on your pan is what should control the flow in the preheater. Remember to solder a tee in the high end of the preheater and then solder a piece of pipe that will go through the top of your hood. Put your valve on that end. That way if you vapor lock you can open the valve and allow it to blow off. Thats what I did when I built my own and it also came through on the one from Leader.

[wiam]

You do not have to have a float. It will make your life a lot easier if you have one. I would not recommend using just a valve but it could be done. That is how Leader's half pint works.

[maple flats]

You have a float box controlling your pans, right? If yes that is all you need. If not, I suggest a float box to maintain level in the pans and just let the flow thru the preheater be controlled by the pan needs. With just a 2x3 pan, if you don't have a float on the pan, use a ball valve to controll the level in the pan.

[Pibster]

Last year I used copper tubing wrapped around the stack, controlled the flow out of the tubing with a small valve. Worked alright but I want hotter sap this year. I guess I should start planning to build a float box. Thanks.

[wiam]

After rereading and just to be clear...........How do you control the flow of sap into your pan? With a parallel flow preheater you do not need to control the flow into the preheater. You only need to control the flow into the pans the same way that you do now (after the preheater) You want sap to sit in the preheater while it is waiting to get into the pan.

[Pibster]

I guess I was hoping that I could control the flow into the preheater since it will be impossible to adjust a valve on the end of the parallel preheater once it's inside the steam hood.

[wiam]

The preheater pipes need to be full to get the most heat transfer.

[Pibster]

I guess I'll have to tweak my plans. Thanks.

[maple flats]

Even if you go very basic, you want the valve at thepreheater outlet not inlet. You can just have a valve there to adjust if you keep close watch. A float gives you some degree of safety if you get doing something else. When I had a Half Pint the preheater just had a small ball valve to regulate the flow. I let it run at a very small stream when things were running good. At times I had to adjust. If you don't get a float box and valve made just use a valve. As you tweak the system you will want a float valve of some type in time.