HWT+Tankless heater for recovery

Is anyone using a hot water tank, instant (tankless) hot water heater and recirculating through recovery? This is similar to how they are doing the I/O extractor. I looked up and crunched some numbers on some cheap ass Rheem units and it’s adding up.

Just looking to see if anyone has home brewed this type of recovery.

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Fickle has shared pics of his plumbing of how he set his up in a couple other threads. I think cyclopath did too. Iicrc

I read your post again I don’t think fickle (or Cyclo) use a hot water tank on their systems. It’s been awhile since I read that thread.


Yeah, pictures posted somewhere.

Never bothered with a tank.

Built my own first tankless.

Ran an iron fist ex-40 powered by a little eco-smart along these lines https://www.hubpors.com/product/lsowat-ecosmart-eco-18-electric-tankless-water-heater-18kw-2-bath/


Thanks to puparoo I expanded my search-fu and landed

Very nice! I’ma send it.


There are at least a dozen threads that touch on the subject…

This was just a 1500W water heater element in iron pipe.

In hot water... has some useful info. Including pictures of an appropriate plumbing layout


If you’re going to use a tankless heater on recirc, make sure that you’ve got one that is designed to handle recirc - many cheaper home grade ones are not, and apparently get cranky if you feed them hot water.

Most commercial grade ones should be just fine. I’ve got the Rheem Commercial series on the BOM for a potential future expansion were considering.


That may have been what @sully was running into…

All the time. Used a tankless instead of the one luna supplied and it worked much better. Just get one that outputs the Btu’s that match your chilling power on the other side and your golden.




I disagree with you that you need one to match your cooling power. You aren’t going to over heat it, it’s just going to cool whatever vapor is created. I used to run a 52k unit and never had any trouble with if being fo big


Why would you want more btus of heating then your chiller can condense? Just a waste of power.

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Because buying a really large heater is super cheap. Like $700

Runs on gas and you only uses what you need. If the return water is still hot, it doesn’t take a ton of energy to heat it back up to the right temp

52kw was $700

Why would I go try to find a small ass one just to match BTU’s?


An overpowered heater will cycle very often. If you go with an overpowered one you really need a holding tank. Our 350k btu heater is such a pain because we only need about 100k btu. I didnt say anything about small, just said its best to match your condensing power. Your saying to buy a 1000 hp car to drive 10 miles a hour. Yea you have all that extra power but you cant use it.


350k btu!?!

I hear what you’re saying but you’re on a very very different level with a heater THAT large.

This is really only the case in your instance with a 350k btu heater.

I’m suggesting a large home unit which is still large. But nowhere near the monster your dealing with.

100k is enough to recover 30+lbs a minute.

You actually using all that?

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This is a boiler, used for ffe. Op is asking about a collection pot.

we only use the heater at 95 degrees and im not sure how that calculation works. If it fires 100% of the time at 95 degrees would that assume its using all the btus? Does temp not matter? Im not a expert here. Not sure how 100k btu would do 30 lbs a min. Our luna had a 55kbtu heater and would get about 4-5 lbs a min of recover, sometimes 6lbs if we turned it up all the way.

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My bad. Your engineer was way off

Yea we use the “Boiler” as a heater as it can be used for domestic hot water. It also powers a few other things besides our 200l collection pot and vapor traps/ molesieves. My whole point was dont need to buy a massive hot water heater for a small set up. If you have a small coil and dont have access to metric tons of dry ice then one only needs a heater that keeps up with their recovery.

This was installed for an av-15. Instead of using the huber kiss heaters that could not keep up with production, we used this. It was already there and not being used at the time. I had the same thought as Fickle when I hooked it all up I was like bigger should be fine and it will just not run much. Im just explaining the pains ive had to deal with running a Massive heater that was not intended to be paired with a collection pot. Im just trying to say if you have the ability to pair your heating and cooling why would you go oversized.

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I’m suggesting a 52kw home unit not one built for a mansion.
350k btu is enough to feed a 28 bedroom house.

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