Tankless Water Heater Tek

Hey Future Fam,

I am trying to upgrade our heating for our honey pot to a tankless water heater. I ended up hiring a 3rd party mechanical company to plumb everything and setup a pump they thought would work best.

This is what they left me with. The pump they’re using isn’t giving us the flow rate we need and don’t think it will keep up with anything we’re trying to achieve. They have a phone call back to me to explain why it’s not working. They’re also saying because I have to run it constantly that we’re going to be going through a lot of pumps.

Can anyone with some input on their heating systems provide me with some insight on what to tell them to make this work.


Seek here: Search results for 'In hot water' - Future4200

Plenty of discussion on the subject.

If they didn’t spec a hot water circulation pump, they may well be right, but grundfos and taco both make pumps very well suited to the task.

There is even math to figure out how big a pump you need lying around here somewhere…

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I am actively reading all of those topics but everyone uses a different set-up it seems. I’m picking this job up after the mechanical team left so I’m trying to learn plumbing and circulating pumps on the fly.


So start in the topic by that name (in hot water…)

Shows how and why. Iirc

There should be things they all have in common. like an expansion tank, which yours does not appear to have.

Ethanol recovery maths - #11 by cyclopath

My previous we extractor, who was heading up this project, had me purchase these pumps as well. The 3rd party mechanical team I hired didn’t want to use them and instead used a different one that I think isn’t applicable. I’m basically firing them and trying to figure out the best options based off what I have or what I need to buy.

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5 gal per min should do dandy.

Or buy a water pump for a small swimming pool.

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The 1/2 horse EZ pump looks like it might work. Smidge large imo.

Buying one actually designed for HOT water would have made more sense

I almost always spec three speed pumps, so I have some wiggle room….

Eg: https://www.amazon.com/Grundfos-52722512-3-Speed-Horsepower-Circulator/dp/B002YR4AVW

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Something like this would work as well. And can operate up to 60c. Which you shouldn’t go nearly that warm, hopefully.


60C works well for hydrocarbon recovery. When using the same trick for ethanol recovery, adding a little glycol and hitting 95-100C happens…which is why I spec the taco or grundfos hot water circulators


Seems you plumber wasn’t quite understanding. I install these systems for houses with heated floors. Rated for constant use with all temps Taco pump is installed here. They make 3 speed versions as well which could help possibly.


“Plumber doesn’t understand” is not uncommon. We are absolutely using this shit off label.


Definitely true. I’m 20 year plumber and if I was not active in cannabis most people would sound like mad scientist to me.


You should get into hplc repair :shushing_face:


I will look into that. In the meantime I am licensed in California if any one needs a consult or contractor. Couldn’t help it ……


Thank you everyone for these answers! I will update once I buy the correct pump and find a better plumbing team.

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I have built “off label” systems like this, and used to build piping systems for geothermal heating in a past life. Is there a blockage of air in the loop someplace? Typically a high-pressure pump is used to purge out all air, and a air eliminator needs to be used, like this one.


I messed with tankless heaters, then got serious and installed an industrial immersion heater. My setup uses a stainless steel grundfos hydronic circulator pump. They are great beacuse grundfos is a great brand, its designed for hot water, its designed for 24/7 usage, good pump curve for our application…


I used a brew kettle because it looked cool.

Then an immersion heater, they can be found many places, but I ordered from Mcmaster Carr because they are reliable but expensive.


Oh fuck I didn’t see the link, my bad

60c is too hot unless you make crude to disty, or just crap extracts. I’ll argue this to the grave.

I think 40c is too hot.


You got a thermoprobe in your puddle?

Temp of your HX fluid and temp of your puddle are radically different for the majority of solvent recovery.

Heating your extract to 60C during recovery would absolutely wreck it. Holding your HX fluid at 60C and cutting it so your puddle only hits 10C, should not.

Luna does all their temps in F for some reason, as does our heater, which we run at 140F/60C, or did last time I checked.

We did have it lower, but bumped it once we got the cuttoff dialed in correctly. My recollection is that we generally are in the 55-60F range when ready to pour, but the boss has been teaching or rig new tricks while my back was turned, so that may not be correct, and the puddle will continue to warm even though recovery has stopped if we are distracted and miss the pour.