Vent for preheater

[schuetz79]

What is the best way to vent a homemade copper manifold preheater. It is being gravity feed.

[TimJ]

I am not sure what "the best" way would be, but we built a parallel flow preheater from copper. WE put a T in the "high" side of the output manifold - one pipe sticks straight up with a pipe that goes as high as the holding tank (vent) and the other goes down into our float valve.

Next time I am at the sugar house I will take pics. Basically as I understand it you need to put in a vent at the highest point to allow air to escape. And the output of the vent needs to be higher than the level of your sap in the holding tank.

I hope that is clear.

Again - I am just a newbie, but it seems to work.

[Dan W]

I think Tim is right. Idid noit build my pre heater but that is how mine is. Where the sap comes out of the pre heater, (the high side) it tees off. Up is to the vent, down is to the float box.

[wiam]

All TimJ says is true. I will add either run end of tube into holding tank or some container. Sometimes when air bubbles up though mine there is a very small amount of very hot sap that comes out. This can be annoying at best or worse. Be safe first. This was with end of tube 4' above sap level in tank. My tube is 1/2 inch and I wonder if bigger tube would let air come up by the liquid??

[Maplebrook]

Have a look at this post.

Darren

http://mapletrader.com/community/showthread.php?15011-Hood-Question&p=168812#post168812

[smokeyamber]

Ok I read the other thread and have a quick question, is the inlet or higher than the out let of the preheater. I get the idea about the vent, just confused by what seemed like the recommendation to make the outlet higher than the inlet... I will be making one of these so I don't want to get it wrong...

[SSFLLC]

If the outlet is lower the sap in the preheater will just run through. So you want a little restriction 2 or 3 inches for the sap to heat up. Hot sap will rise before cold sap.

[Dennis H.]

My preheater has 4 outlets. They come out the back of the hood 2 on each side, one above the other.
I have the sap coming in on the lower right side and the sap coming out of the preheater on the upper left.

Here is what I did with the other 2. The lower left one just below the outlet to the float box I have a ballvalve the allows me to drain the preheater into the floatbox.
The other one that is above the inlet to the preheater I have a stub of copper pipe with an end cap on it, I then took one of those saddle valves that you see being used for ice makers and such, I then took some 1/4" tubing and ran it into the floatbox.

I adjusted the saddle valve so that it trickles sap very slowly into the floatbox. I have it so that it is more like a dribble than a stream.

I have now ran this setup for 3 long boils, about 6 hrs, and a 3 hr boil and never had any issue of any kind with the preheater vapor locking.

[smokeyamber]

Great info Dennis ! The details about the drain and the vapor-lock prevention setup would have not occurred to me at all. So now I will shameless copy your design :evil: Sounds like you are hard at it this season already, I have a couple of weeks yet up here in VT, but looking forward to it already !!! :D

Hope you have a great sugaring season !

[Dennis H.]

As good as an idea as it is I can not take credit for it. I was told this by Sugarmaker here on the trader.

Yeah I am in full swing down here, and the weather forcast just keeps getting beter and better. I see little sleep in the near future!