Modulating Auto Draw-off

[ennismaple]

We've been using the Electrogen auto-draw off for the last 15 years. It's reliable but it's time to go to a modulating auto draw-off to get a more consistent flow and less "slugging" of syrup through the front pans and more consistent Brix in the finished syrup tank. Every manufacturer has one in their catalogue so let's hear your opinions - good, bad and indifferent.

CDL
Lapierre
D&G
H20 Leader
LS Bilodeau
Other recommendations?

[Pdiamond]

I have the Smoky Lake Simplicity auto draw off system. Been using it for 9 years. I have only had the valve stick one time with niter build up, and a quick rinse with hot water fixed that. I had a fluctuation problem one year, that was my own fault. The wire for the probe got just a little to close to the arch and was getting hot, I caught it before any serious damage was done. Once it cooled off, I placed some electrical tape on that spot and now make sure that the wire is a long way from the arch.

[johnallin]

I've had an H2O EVEN-FLOW modulating and barometric automatic draw-off for 4 years now. No complaints at all.
Set it and you're done. Modulating feature is amazing as it will open anywhere from 5-100% and back depending on syrup temp.
I'd recommend taking a good look at it.

[mainebackswoodssyrup]

That's good to hear you are running it in your 2x6 John. What brix are you boiling at? What size valve is it, 1"?

[ecp]

I run the CDL modulating draw off so here is the good/bad on that brand. The good is that it works every **** time and it was cost friendly. The bad is you need to make sure the probe doesn't get caked up and start ups are rough (once you are used to it the first slug isn't that bad, but it still pissed me off). I don't think the controller is actually modulating-PID driven but rather changes the position of valve by about 8% every tenth of a degree above setpoint so you end up needing to set the setpoint (for me) 6 to 7 tenths of a degree below actual syrup. You still need to check is as the boil continues but there are not a ton of adjustments that you need to make once its set

In general, I hate the idea of Butterly valves because of the pipe restriction from the valve and the modulating flow rate is not as linier but it works. A ball valve would work better IMHO but I couldn't find that option in the size we needed at the time we received it.

Whatever you go with don't skimp on the size of the valve and make sure it is the same size as the port on your evaporator. All things considered I probably would have gone with H20's even flow with barometric compensation if price wasn't the issue.

[johnallin]

That's good to hear you are running it in your 2x6 John. What brix are you boiling at? What size valve is it, 1"?

Normal over here is 6-7%. Pretty sure it comes with a 1" valve but I'd have to look that up or go check the sugar house.
It's flawless as far as I'm concerned and adjusts draw-off temp automatically with changes in barometric pressure.

[mainebackswoodssyrup]

Good to know, thanks John. Would like try one as well on our 2x6 once we are boiling RO'd sap.

[Brian]

I have a Lapierre and love it. The only problem is they get sticky. I run a manual valve behind it to regulate the flow a little. When I run water through the front pan to clean it, I leave the auto draw off open and the water running through, cleans the niter out of it in good shape so it is ready for the next go.

[TapTapTap]

I've been confused about the modulating draw-offs since last year when I looked into replacing my non-modulating setup. I thought I understood from looking at various systems from suppliers that the modulating feature is available only on 1.5" and larger piping, and I thought that would be for butterfly valves. It sounds like the modulating feature might also be available on the 1" piping and with a ball valve. I just today looked at some of the websites of the suppliers, I found it difficult to see whether their systems are either modulating or butterfly vs. ball.

What are others understanding?

Ken

[johnallin]

I've been confused about the modulating draw-offs since last year when I looked into replacing my non-modulating setup. I thought I understood from looking at various systems from suppliers that the modulating feature is available only on 1.5" and larger piping, and I thought that would be for butterfly valves. It sounds like the modulating feature might also be available on the 1" piping and with a ball valve. I just today looked at some of the websites of the suppliers, I found it difficult to see whether their systems are either modulating or butterfly vs. ball.

What are others understanding?
Ken

Looking again, the H2O I have has a 2" butterfly valve behind a 2" spout.
A good feature for smaller rigs as in my 2x6 - is the ability to have it open less than 100% when it calls for a draw. I'm set at 50% when wide open.

[TapTapTap]

Looking again, the H2O I have has a 2" butterfly valve behind a 2" spout.
A good feature for smaller rigs as in my 2x6 - is the ability to have it open less than 100% when it calls for a draw. I'm set at 50% when wide open.

That's what I recall and my concern was that too much syrup would set between the valve and the syrup pan with a 2" or even 1.5" valve/pipe. So I decided to stay with my current un-modulating system. I'm able to still adjust the full-on flow with another manual ball valve just ahead of the autovalve.

Ken

[Bricklayer]

I currently have the CDL modulating draw off.
Pretty happy with it.
I originally had built my own copy of the CDL one for last season and had some issues with it. So I purchased the controller unit from CDL.
It acts the same way as the home made one does.
So I’ve come to the conclusion that being wood fired and having a modulating auto draw has its issues.
I fire by firebox temperature and not time. This seems to keep the boil somewhat steady. But even opening the door and loading for the 15 seconds it’s open drops the temp of the syrup pan. The auto draw controller senses this and adjusts accordingly and saves the data and expects that the change will be the same next time. So I find that it’s not a true modulating drawnoff because the PID is in relearning mode every time it gets close to drawnoff temp. I assume that on an oil rig with a constant temperature that it would work a whole lot better.
I still get constant draw offs and no big spikes in temperature like I did with my open close auto draw off I had before. It keeps the draw offs small and steady. I think this would be the case with all modulating draw offs on all wood fired rigs with a fluctuating boil temp because the PID has to know how much to open the valve to affect the temp of the syrup amd for how long. When you have a fluctuating temp of fire controlling the boil it changes with every fire minute by minute.
Having the butterfly valve and the belimo controller like almost all modulating draw offs have is the best worry free part of it. After struggling with open close ball valves and nitre build up clogging them for years I would never go back to anything but a butterfly valve for a draw off. Never had it clog or fail on me. The belimo controllers are strong enough to close the valve no matter how much nitre is flowing through them. 2” valve is what I have on my 30” x 10” evaporator. I have it set at a little over 1/2 to open fully. And never had a problem. Having it fully open at 2” full bore while running I would Probley have a heart attack watching the levels.

[johnallin]

That's what I recall and my concern was that too much syrup would set between the valve and the syrup pan with a 2" or even 1.5" valve/pipe. So I decided to stay with my current un-modulating system. I'm able to still adjust the full-on flow with another manual ball valve just ahead of the autovalve.

Ken
Not home to check right now, but pretty sure my Revolution pan is 1" pipe off the boxes. The H2O connects from the 1" to the 2" with a TriClamp fitting.
I don't think there's really any more syrup sitting in the pipe than before but could be wrong.