Recirculating Dephlegmator Liquid

Hi all!

It's been a long while since I posted here, but wanted your input on a bit of a brain-buster :)

Looking to recirculate water through a dephlegmator, rather than use a constant mains water stream.

We're operating on a commercial scale here, so the liquid is stored in a 1000L IBC container, and is a glycol mixture.

My thoughts are to use a bilge pump (self-priming, 'silent' operation, anti-spark, long-life), submerged in the glycol mixture, pumping through the dephleg (and condenser), with a return-line back through the top of the IBC.

My only issue with this is being able to turn the pump off, and on again if I wish to shut the flow to the dephlegmator (in the case of controlling vapour running through it). In control systems that operate with solenoids, the flow is either off and on. I would love not to have the pump running whilst the flow isn't open.

I was thinking along the lines of a garden pump, which shuts itself off when the flow turns off, and starts up, when flow is open. Or even pump systems that are attached to houses hooked up to rainwater.

What do you guys use?


  • You really are better off with separate control valves on each condenser. You will need the product condenser to be running for the entire run. That means that your pump will be on also.

    Just control the coolant flow to the dephlegmator independently and accept that the pump will be on whilst the boiler is in use.

  • edited April 2014

    The way to control the pump is by using a solid state relay triggered by the same source that is triggering your solenoids. If either the dephleg. solenoid or condenser solenoid are triggered, the pump should run, if both are off, the pump should be off. How this is wired is going to depend on what kind of controller you are planning. Or, you could use two smaller pumps with SSRs and skip the solenoids entirely.

    Keep in mind your submersible pump may be adding additional heat load to your cooling system.

    Big disclaimer here is that you need to understand how the system will react if your controller, pumps, solenoids, or wiring fails. KISS would indicate that the pump should always be running while the still is running (since running pumps tend to continue to run), and that the condenser plumbing should not include a solenoid (an additional point of failure, which may close on failure). In this model you only need to control 1 solenoid on the dephleg.

    What are you trying to accomplish here - why not just two manual ball valves? And why are you using a glycol mix in the IBC? Are you trying to cool it below freezing?

  • @UZGin I personally use a submersible grey water pump, that has a the outlet on a "T" with the main outlet going to the equipment/valves/taps whatever, the side T connection is a hose back into the tank for a pressue relief setup. You loose a little bit of pressure to the main outlet, but when thats shut off, the pump still copes well just with the small return path (also have a tap always on, except for empty/cleaning)

    The pump I use are not rated for hot temps over 40c, and don't like to be run all day either, however they where cheap and easy to replace. Using submersible pumps also cuts back on the noise, they are quiet in operation vs a stand alone pressure pump. The main thing to note is our hobby set ups don't need much water flow to operate. 4" dash is about 0.5lt -2 lt min.

    On a commercial scale, the pro's and serious semi pro's should be able to guide you in the correct direction.


  • If you are not dedicated to turning the pump off, but trying to mitigate damage to the pump from running against a closed stystem then a 3 way ball valve is what i use on the pot still so when i adjust the water to the condensor the excess just runs back to the tank.

    On the Crystal Dragon i have the same setup as fadge.

    Grim has it nailed if you actually need the pump off.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • I use a submersible pump designed for an irrigation system. These are intended to pressurise a water distribution system to run sprinklers and hoses so have no problem powering through valves to control flow rate through condensers. The entire distribution is pressurised to mains power of 1 bar.

  • edited May 2014


  • edited May 2014

    The easy way to do this would be to fit a pressure relief valve to direct the coolant away when the solenoid valve closes, simple.

  • So I have a very similar setup at our distillery, though slightly different. I have a 1000 liter IBC that has its own glycol chiller. The IBC is full of water and has 20 feet of cooling line from the glycol chiller submerged in the IBC to keep it 45 degrees F. The glycol chiller is your standard DIY style with a 48 qt cooler full of glycol and a 12,000 btu window ac unit hooked up to a Ranco, the ranco takes the temperature off of the IBC and not the glycol cooler. The cooler has a 1/4hp continuous duty sump pump to push the glycol through the cooling lines that are submerged in the water in the IBC. In the IBC there is a 1/3hp continuous duty sump pump. These pump something like 40 gallons per minute. So I have 3 connections to this pump, one goes to the dephlag, one to the product condenser and one to recirculate the water in the IBC. All of these have their own ball valve at the bottom, as well as a needle valve for the amount of flow that the dephlag and condenser receives. I would say it is better to run the pumps the entire time and control the amount of water passing through. Having good recirculation in the IBC is nice as well. I actually just picked up another IBC and parts for the glycol system and am going to run both at the same time and continually recirculate both together. Its a cheap 2 ton 550 gallon water cooling tower that can handle both my 500L 8" Still Dragon setup and should be able to run the steam stripper that I just ordered all the parts for.

  • Hey guys! Cheers for the replies! Just a few quick things:

    • I'm looking to use glycol, not just for its freezing/boiling temp alterations, but it also contains a preservative that will prevent the recirculating water going stagnant. I don't want to fill a 1000L IBC every time I want to utilise the still. I want to fill it once. As per our waste water agreement with the EPA (in Australia, things are a tad strict), all water must captured and carted off-site...1000L of waste water is a fair whack to pay in removal fees too - around $300 each time. I have to keep this in consideration.

    • Completely forgot about that condenser being shut off, my bad...massive Rookie error. Looks like we'll have to Y/T-Piece it and keep the pump running, regulating the flow to the Dephleg.

    My concern is the speed of the pump...if we require only 2L/min (max)...then finding a sub-pump that low will be difficult. It's almost worth looking at a little fountain pump! We've got a 300L boiler with 4 inch Diameter Column.

  • Just divert what you are not using back to the source with a 3 way valve. Nothing simpler.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • edited May 2014

    but it also contains a preservative that will prevent the recirculating water going stagnant.

    It also means that at some point in the future, you'll need to deal with 1000 liters of glycol tainted water.

    Use water and straight bleach, buy a handheld ORP/REDOX meter (for less than a case of beer) to know how much bleach to use, and when you need to add more.

    Turn on the pen meter, dip it in the water, it'll give you a numerical read out.

    Slowly add very small amounts of bleach while circulating, aim for a ORP target of 300-350mv - this is typical for cooling water applications - you shouldn't need to push much higher.

    This should keep your water plenty clean and fresh.

  • I've run a submersible aquarium pump on a still before. I had it to recirculate the water in the condenser bucket and run cold water up to the deflag, both had needle valves, but I never messed with the recirculation valve, it was always fully open. It was 500ish gallons per hour, which was way more than enough. It was a pretty cheap pump, still works great and I would mess with the amount of flow to the deflag all the time, turn it off to run out the tails. I never really seemed to have a problem with stagnant water, I used that water first whenever I needed it. Pump it over to your hlt and use it whenever you brew, clean, etc. My town/county is in the same regards to water usage, which is one of the only reasons I went with a cooling tower, to conserve water. We've had a couple bad snow years followed by some mediocre monsoons. Maybe next year we will get that 500" constantly snowing, blower pow year.

  • edited May 2014

    According to this Dow Chemical manual - glycol concentrations below 25% are actually at a higher risk for bacterial contamination. Are you really planning on adding more than 250 liters of glycol to the mix?

    Also, above freezing temperatures, glycol will actually reduce the thermal conductivity of the water. By doing this you are reducing your overall system performance. In addition, without adequate corrosion protection you may be damaging your equipment:

  • Great Idea Grim! and cheers for the activity and research!

    However, I have no issue with dealing with glycol tainted water. But I do have an issue with bleach, because we're in a winery, bleach is a no-no. It promotes the development of something called trichloroanisole (TCA), which most people know as cork-taint.

    Was planning on using radiator fluid...which contains a mixture of chemicals to protect from corrosion.

    We wouldn't be adding any more than 10%. The same as we use in the winery's chilling and heating lines.

  • Just read through that Dispelling The Myths pdf...awesome!

    Will probably roll with the Dowtherm SR-1 fluid.

  • What would be the issue with using a rainwater tank? Assuming your local council is going to make you put one in on a new building anyway, why not just use that water recirculated?

    That's how my system is set up, pump in and out of the tank that is plumbed as usual, rainwater from the roof in, with the overflow going to storm water.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • Long story needs to be relatively mobile.

    Forklift the IBC in, Forklift it out.

    The way the building is set up (already existing), it's quite hard to do what you're on about, even though the idea is completely valid, and would certainly work.

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