Recirculation needle valve and where to plumb lower end

[lastwoodsman]

I am thinking of putting in a recirculation side to my homemade ro. If installing the needle valve on the concentrate side. Where do I plumb the lower end or where does it feed into?
Right before the sap enters the membrane on the bottom side?

[Bricklayer]

Put a tee right before your concentrate needle valve. Run the recirc to a separate needle valve. Then to a flow meter. Then to the intake of your High pressure pump.

[lastwoodsman]

Put a tee right before your concentrate needle valve. Run the recirc to a separate needle valve. Then to a flow meter. Then to the intake of your High pressure pump.

Should I tie into a existing flowmeter or add another?

[Bricklayer]

A separate flow meter. A flow meter on recirc line is not necessary. But it’s nice to have. Your concentrate flow meter is for concentrate out. Meaning concentrate being sent to head tank to boil.

[bill m]

What is the advantage to installing a needle valve for recirculation verse just redirecting the concentrate back to the sap tank and letting it recirculate till you get it to the concentration level you want then sending it to your head tank?

[Bricklayer]

What is the advantage to installing a needle valve for recirculation verse just redirecting the concentrate back to the sap tank and letting it recirculate till you get it to the concentration level you want then sending it to your head tank?

This method works as well. I’ve used it before to achieve higher concentration. But it takes a long time. You are constantly adding concentrated sap to fresh sap. Then sending it through RO again.
I just find that with a recirc line I get better results. I run my recirc at 5gpm on my RO. And .75 gpm of concentrate.
This gets me boiling 30 minutes after I start RO and have enough in the head tank to fire up. By the time I’m boiling I have 40 gallons on head tank and it stays that level till RO shuts off.
The recircung back to sap tank takes hours untill you have an even concentration.

[lastwoodsman]

I experience as well.

[lastwoodsman]

A separate flow meter. A flow meter on recirc line is not necessary. But it’s nice to have. Your concentrate flow meter is for concentrate out. Meaning concentrate being sent to head tank to boil.

Thanks for all the input !!!!

[lastwoodsman]

This method works as well. I’ve used it before to achieve higher concentration. But it takes a long time. You are constantly adding concentrated sap to fresh sap. Then sending it through RO again.
I just find that with a recirc line I get better results. I run my recirc at 5gpm on my RO. And .75 gpm of concentrate.
This gets me boiling 30 minutes after I start RO and have enough in the head tank to fire up. By the time I’m boiling I have 40 gallons on head tank and it stays that level till RO shuts off.
The recircung back to sap tank takes hours untill you have an even concentration.

My experience as well

[lastwoodsman]

Thanks for all the input !!!!

Are you using the same type of flowmeter as on my panel or some type of inline meter?

[Bricklayer]

Are you using the same type of flowmeter as on my panel or some type of inline meter?

Same style. I have a 1-10 gpm for my recirc. Could probley get away with a smaller one say 1-5 gpm flow meter. But sometimes I run it wide open and it will go to 8 gpm. But 5 seems to work the best and control the pressure the best.

[cjf12]

Do you have a brand for that flow meter? How does it hold up to that psi? Struggling finding one rated for that kind of preasure.

[lastwoodsman]

Do you have a brand for that flow meter? How does it hold up to that psi? Struggling finding one rated for that kind of preasure.

I used lzt from eBay. Works fine. Although right now they are not listing a 0-10gpm model.

[maple flats]

Your flow meters are after the pressure, at that point they are open discharge. Even the recirculate is low pressure, it is feeding non pressurized flow to the high pressure feed inlet.

[lastwoodsman]

Your flow meters are after the pressure, at that point they are open discharge. Even the recirculate is low pressure, it is feeding non pressurized flow to the high pressure feed inlet.

I think I understand what you are saying. Should I be running a needle valve off the other high pressure side Of the membrane to the existing flow meter and then the outlet of the flow meter to the low pressure side intake of my pump.
I would use the valve on the top of the membrane to control outlet pressure.

[Bricklayer]

If you are installing a recircirc line you will need 2 needle valves
Concentrate Line comming off your membrane goes to a tee with 1 side going to your concentrate needle valve then other side of needle valve goes to flow meter. Other side of flow meter heads to your concentrate tank.
Recirc line connects to the tee off the concentrate line from the membrane. Goes to a needle valve. Other side of needle valve goes to a flow meter. Other side of flow meter heads to you inlet of your hp pump where you will need a tee as well.

[bill m]

This method works as well. I’ve used it before to achieve higher concentration. But it takes a long time. You are constantly adding concentrated sap to fresh sap. Then sending it through RO again.
I just find that with a recirc line I get better results. I run my recirc at 5gpm on my RO. And .75 gpm of concentrate.
This gets me boiling 30 minutes after I start RO and have enough in the head tank to fire up. By the time I’m boiling I have 40 gallons on head tank and it stays that level till RO shuts off.
The recircung back to sap tank takes hours untill you have an even concentration.
I find recirculating back to my sap tank not a big deal. I start my RO after I truck in the first load of sap. I set my pressure about 300psi and concentrate flow of 5gpm. By the time I have everything trucked back ( 3 of 4 loads ) the sap is up to 8 to 10%. I then tighten down the needle valve to about 13 to 14%. While the head tank is filling I drain the permeate from my syrup pan and pump the sweet back in. By the time that is done I have about 150 gallons in my head tank and start boiling.

[jrgagne99]

I added a recirc line to my Waterguys single-post RO for this year and love it. Previously, I recirculated back into the truck tank until it was sweet enough, then pumped overhead to my head tank on one final pass. It took around 2 hours to concentrate my typical 200 gallons, before I could start my boil. With internal recirc, I can control my RO output to 8 brix and light the match within 15 minutes of starting the RO. This was a game-changer for me this year. A single post at 8 brix output keeps up pretty good with my 25 gph boil rate. Limiting concentrate to 8 brix lets me go the whole season doing rinses only, then I do soap wash only at end of the season. Works well on a small scale (~50 gallons syrup per season). At 8 brix, you're pulling out 75% of the water. When I go to 12 brix (~82% water removed) or higher I need to do frequent washes. To me, 75% of water removed and 82% are about the same number, so why make more work for yourself? Same thing goes for those high-brix systems... 40 brix (95% of water removed) is really only marginally better than 16 brix (88% of water removed) when you look at it from a water removal perspective. Both are way better than the alternative (raw sap).

Ok, off soap box now.

The only "gotcha" i ran into when I added the recirc line was that my original concentrate flowmeter was too big. The 0.5 gpm of 8% that I make was not enough to raise the float, so I put a cheapo one from amazon inline with my head-tank feed line.

[bill m]

I added a recirc line to my Waterguys single-post RO for this year and love it. Previously, I recirculated back into the truck tank until it was sweet enough, then pumped overhead to my head tank on one final pass. It took around 2 hours to concentrate my typical 200 gallons, before I could start my boil. With internal recirc, I can control my RO output to 8 brix and light the match within 15 minutes of starting the RO. This was a game-changer for me this year. A single post at 8 brix output keeps up pretty good with my 25 gph boil rate. Limiting concentrate to 8 brix lets me go the whole season doing rinses only, then I do soap wash only at end of the season. Works well on a small scale (~50 gallons syrup per season). At 8 brix, you're pulling out 75% of the water. When I go to 12 brix (~82% water removed) or higher I need to do frequent washes. To me, 75% of water removed and 82% are about the same number, so why make more work for yourself? Same thing goes for those high-brix systems... 40 brix (95% of water removed) is really only marginally better than 16 brix (88% of water removed) when you look at it from a water removal perspective. Both are way better than the alternative (raw sap).

Ok, off soap box now.

The only "gotcha" i ran into when I added the recirc line was that my original concentrate flowmeter was too big. The 0.5 gpm of 8% that I make was not enough to raise the float, so I put a cheapo one from amazon inline with my head-tank feed line.
I don't think you should be looking at this just from the stand point of water removal. While going from 8% to 12% is only 7% increase in the amount of water removed it is a 48% increase in the amount of syrup made per hour at your 25 GPH rate. Going from 16% to 40% is still only a 7% increase in the amount of water removed but a 150% increase in the amount of syrup made per hour.

[Bricklayer]

The nice thing about a recirc line with a needle valve is you can close it if you don’t like it or want to use it.
Like I said. I’ve recirc’d sap back into the tank before but I’ve had way better results personally and spent a lot less time cleaning my membrane using the recirc line.