New Head Tank Sizing

[SeanD]

I'm having A and A make a bigger storage tank for me and while I'm at it, I decided to upgrade my head tank. I'm also upgrading my RO to a 250. I'm thinking 125 or 150 gallons for the head tank. I figure that gives me the space for handling the concentrate from 600 gallons of raw sap or more since I'll be boiling while the RO is running. My 2x6 does 35-40 gph. If I run into problems I can send the concentrate back to the sap tank to re-concentrate it.

I'm interested in keeping the head tank on the smaller side so it's easier to handle and clean, but big enough to not need a separate concentrate tank anymore. Do my numbers seem right to those that do it this way?

Thanks,
Sean

[Maplewalnut]

Sean- all depends how you want to boil and what you concentrate to brix wise. I used to be able to start my RO and almost match my evaporation rate . I squeezed it pretty good but I never needed more than 30 gallons of storage in my head tank. Now with a bigger RO I still only have (2) 35 gallon tanks but do wind up filling them both at the end of a run so I can start the RO rinsing and washing. I went to (2) separate head tanks so I can be cleaning one while the other has concentrate. I think 125-150 is plenty big for a couple hundred taps

[Super Sapper]

I use a 55 gallon plastic drum for a head tank. It has an overflow line to the storage tank. I also have valving to bypass the head tank if I want to crunch it some before filling the head tank. I have never found a need for a larger head tank, even if I have 1200 gallons of sap to go through.

[SeanD]

I had a feeling I could be over doing it. I use a 55 gal drum on its side, tilted now and it can hold about 35 gallons when full. I'm always making improvements, but I want this to be my last head tank for a while. I like having the stress-free extra space of the big concentrate tank I have now, but I wouldn't mind filling the head tank directly and getting rid of the steps where I have a switch and a pump feeding the head tank when it runs low.

The overflow line is a good idea for backup if I forget to flip the output back to the sap tank. It's a long run back to the sap tank, but it is downhill. That could work.

[maple flats]

Over the years I've had a few different size head tanks. I first used a 415 gal milk tank, then I got a 200 gal also SS tank free and used that for a few years. I think that was originally used to cool milk using cold flowing spring water which entered the bottom and exited near the top. Then I ordered a 150 gal sap tank from NGMP. Even though it can hold 150 gal I rarely have more than 75-100 gal in it. My rig goes thru between 65-80 gph depending on how hard I push it. I do have it plumbed so I can recirculate from the tank outlet, back thru the RO and back into the tank. Doing that I often get to 10-12%, on one pass I only get 7-8%. I like the 150 size and will likely remain with that. Then on the ground I have 4 sap tanks, but most often only use 2, the old 415 and a 545 milk tanks. If I get moor sap, I also have a 300 gal milk tank. Then my permeate tank is a 1000 gal milk tank.
I think a 100-125 is good if you plan to stay with a 2x6 for a few years, or even a 3x8 or 2.5x10.

[MISugarDaddy]

I have a 250 RO and a 2 x 6 evaporator and have a 100 gallon head tank. That size has worked really well for us. If I had it to do over, I wouldn't go any bigger or smaller. The thing we did after installing it was to completely insulate around it with styrofoam insulation so it doesn't sweat as the sugarhouse warms up. The first year we had it, we had to lay towels under it to absorb the moisture from the tank sweating. Now we have no condensation at all on it and the sap stays cooler to minimize bacterial activity on the concentrate.

[maple flats]

My head tank sets on a sturdy platform against the north wall outside butted tight against the sugarhouse wall. The tank valve is just inside the sugarhouse. It does not sweat. It is high enough that the bottom of the tank is 2' above the float box on the evaporator and the pre-heater in the hood has no issues with air bubbles.

[n8hutch]

I would recommend the 2x4x3 CDL tank, best value out there, 160 gallons, I have been using one for 6 years, it rarely has more than 75-80 gallons in it, but it's handy to wash because you dont need to scrub/hose down the upper regions of the tank , so your not spraying water every where. Also the price is marginally higher than a 100 gallon.

[TapTapTap]

We have a 500 gal SS round bottom, open top with an overflow back to the raw sap tank, and it'sfine but not any too big. It provides good capacity for the 1050 taps with our CDL1200. The nice balancing for us is to have about enough boil time in our concentrate tank to allow for the RO cleaning process to start (flushing the membranes to squeeze out the sugars to the concentrate tank) and then later at the end of boil to chase the concentrate with permeate to make sure we push all the sweet down into the flue pan. We need the RO cleaning and rinsing done befor the boil ends since we use the RO for pumping permeate up to the concentrate tank for the chaser. Since we burn wood, we need the permeate chaser to let the rig to cool down.

[SeanD]

Thanks for all the feedback. I ended up going with the 100 gallon tank for the head tank. The bigger one is my new collection tank (625 gallons). Overall, I'm happy with them, but he made a mistake on the head tank. He put a 3/4" outlet on the bottom instead of the 1" I asked for. I think I might be okay. The 1" valve on my old tank had no problem keeping up with my 35-40 gph boil rate. I'd still use the 1" line, but have to reduce it at the tank. Think I'm literally playing with fire?21507

[Super Sapper]

As long as you do not have a real long run from your head tank to the evaporator you should be fine at that size. I use a 3/4 on mine and usually run in the upper 40's to low 50's and have no problem.

[maple flats]

I think the 3/4" outlet immediately increased to 1" will be fine. If in doubt, raise the tank so the outlet is at least 3' above the float box sap level so gravity helps too.

[SeanD]

Phew! Thanks for the peace of mind, guys. It's about a 4' run and about a 2' drop or so. I can adjust the height easily enough if I need to.

New question - The head tank is 2'W x 3'L x 30"H and it sits on a flat platform to support the bottom. It feels rigid enough especially compared to the big tank. Do you think I can go without a frame for it?

[DrTimPerkins]

I think the 3/4" outlet immediately increased to 1" will be fine.

This is correct. If there is a restriction, but then the "stream" widens out again, the flow will be faster (but lower pressure) through the restriction, then slow down again (but increase in pressure) in the pipe afterward. This is called the "Bernouilli Effect", and is similar to what happens in the air stream over a plane wing.

You can think of it as a river that comes to a bridge with abutments along the side. The river might be wider above and below the bridge, but water doesn't stop or build up overly much (most of the time). The water runs faster right under the bridge than it does slightly upstream or downstream to compensate for the restriction.

Interestingly, some recent research we've done with students over the past few years (thanks to funding provided to UVM PMRC by the Chittenden Co. Maple Sugarmakers Association in Vermont) indicates that the sap stream within a tree stem seems to behave in the same way around a wound (and the associated stain). This is why a tapping (at recommended levels) over several years doesn't seems to affect sap flow rates or yields. The speed of the sap moving AROUND (not through) a stained (non-conductive) wood area increases locally within the stem, but then slows down again once it is past the wound. The end result is that the tree can still effectively move sap past wounds (as long as the affected area isn't excessive) without negative consequences on sap movement to the tree crown, or to sap being collected in buckets or the tubing system.

[SeanD]

Giving this thread a bump to ask a question about my head tank. I'm not sure if I need to build a frame for the sides of it or not. It is 24" W x 36" L x 28" H and holds 100 gallons. I'm going to set it on a reinforced plywood base, but it feels like the sides are short enough to handle the outward pressure of the sap. The seams are crimped, riveted and soldered and the top edges are bent in to a lip that runs all the way around it.

Can I get away with leaving it as is or should I reinforce the sides with a wooden frame?

[Pdiamond]

Sean mine is smaller at only 50 gallons same kind of design with a lip all the way around. If you have any doubts frame it in.