pre heater type

[maple connection]

I have a 2x6 grimm evaporator with a 2x4 raised flue pan. I am thinking about making 4 runs of 1" copper tubing inside my steamhood. With some kind of tray under each run to catch the water. Does anyone have any advice? Not sure on the size of pipe and the # of runs. Thanks, Kevin

[waysidemaple]

My preheater is made out of 1 inch copper pipes. It has two rows of 4 pipes.

[maple connection]

Are you happy with the temp. of the sap coming out of the preheater.

[waysidemaple]

I wish I could answer that. I haven't had mine up and running yet. Just got it plumbed in the other day.

[maple connection]

O.K. good Luck with your new rig. Thanks for your input.

[markct]

i have 4 runs of 3/4 copper in my 6ft flue pan hood on my 2x8 evap and it comes into the float box at about 180 to 200 deg usualy, so i am very happy with it, i dont have a damper to hold the steam back a bit which would help to increase the efficiency a bit, planned to install one but it worked well without it so didnt bother

[maple connection]

In that case, My flue pan is only 2 x 4 so 1/2" or 3/4" would maybe be big enough.:)

[Maplebrook]

I made my preheater with 3/4" copper for the headers and 1/2" for the pipes. There are 5 pipes off the header, each 36" to a 180 and then 36" back. This makes a total of 30'. It would heat to 180 - 190 with no damper on the stack.
I used 3/4 copper for headers and drilled a 5/8 hole(carefully!) to solder(more carefully!!) the 1/2 into to give me a narrow enough header to fit the 5 pipes. Soldered end caps on and pressure tested - success! I looked at the infloor heat headers but they're expensive and too much space between the outlets.

[maple connection]

So the header connects them all together. I was thinking of bringing the sap in the first pipe and making it flow threw all of the pipes and out the last pipe into the float box. I was just going to use two 90's at the end of each pipe with a 2" piece of pipe to space them out. I will need a relief valve for steam some were from what I gather.What is the header do?
Kevin

[WESTVIRGINIAMAPLER]

Kevin,

I have some pictures of the preheater I built out of 3/4" copper thin walled pipe in my signature below. Works good and average around 175 will very little dampering.

[Maplebrook]

Kevin,
When you design your preheater, you want the sap to flow uphill to prevent air in the line from vapor locking your preheater and stopping the flow of sap. A continuous zig-zag of pipe is hard to keep flowing all uphill with no low or level spots. Using headers, the inlet header is low, the pipes run uphill to the outlet header, and then to the float box. At the highest point on the preheater, you don't necessarily need a steam relief valve, as the preheater won't boil sap, but a valve or tubing to allow any trapped air to escape.

Cost wise, I read where you wanted to build this from 1" copper. After doing a little math, it takes 4 pieces of 1/2 in copper to equal the same flow of 1 piece of 1". I you want continuous 1" flow from tank to float box, use 1" headers and at least four 1/2 " preheater tubes, and you will get the same flow, use cheaper 1/2" pipe, and expose more sap to the steam. The smaller the preheater pipe, the more heat you'll glean from the steam. Just make sure the preheater pipes equal or exceed the header in terms of flow.
Darren

[maple connection]

Thanks for that info. Do I need something under each pipe to channel the the condensation into the steamhood water channel?
All this info is drawing a more clear picture on how I should build one instead of building one 10 times before it works.

[Maplebrook]

I have a pan attached to the underside of the grid of pipe. It is slightly larger to catch all the drips, and runs into the channel on the inside edge of the hood via a small trough. Keep in mind that the hood will fill with steam and surround the pipes - you don't need the pipes exposed to the direct steam rising from the flue pan. I built mine from aluminum flat stock(for making fascia) using the brake at the local hardware store.
Keep studying...I did the same thing. Well thought out and it works fine!