Water-air cooling discussion

Whats up guys, been a while since i been on here but im getting ready to start a new run and have been juggling this issue around for over a week, done countless hours of research and can't work this out so thought id bring it here to see what you guys might suggest.

Just upgraded to an ebb and flow bucket system, got my ecoplus 1/4hp chiller on the way currently, What i want to do is use the chiller to cool my rez obviously, but also to run an "icebox" (hydro innovations product name) in my intake duct to help keep temps down during the upcoming hotter months- Before going any further let me just pause to say do not tell me to get a window a/c, if i wanted to waste electric i would just crank the house a/c down and be done with it- My tent temps dont get crazy hot, just looking to drop the temp of the air coming in the tent by 5 degrees or so which this system is more than capable of doing.

The issue that im juggling is that the hydro innovations icebox is made with a copper core, which means running low ph nute solution through it is an obvious no-no (even though i have several growers with 20+ years under their belts telling me itll be fine ), what HI would have you do is run a separate reservoir just for the chiller and then run a wort-style chiller pipe for the rez then tied to the icebox, which isn't a bad idea but requires more space than i have available. What would be ideal for me would be to have a supply pump in the nute reservoir pumping to the icebox>icebox to chiller>chiller back to nute rez, but this of course means i need a heat exchanger capable of having the nute solution pass through it without corrosion or leaching.

I've come across a couple DIY icebox threads on various forums where people used random automotive heater cores to make their own icebox but the issue i see with that is those are usually aluminium which will inevitably have the same corrosion and leaching issues that copper would.Seems titanium and stainless steel are the only two options that can work, but i cannot find a small heater core made of either of those materials to save my life..
One solution i had though of is instead of a "box and fin" style heater core i could use a stainless steel coil (pretty much just a small wort chiller pipe) ran inside the intake duct that would work under the same principles (warmer air passes over the cold coil and cools it) but the surface area of that would be piss poor i think unless i could custom make one somehow (which is beyond my set of skills i believe lol).

So now that you've read this wall-o-text im eager to see what you got in mind, if anyone happens to know where i could find a titanium or SS heater core id be most excited to know where! Thanks in advance guys!

Something i just thought of- not sure it would work, hopefully someone will chime in on this, rather than trying to coil hard stainless steel tubing by hand i came across this "icemaker hose" that uses non-toxic pvc hose for the inner layer and braided stainless steel outer layer, heres an example of it
https://www.lowes.com/pd/EASTMAN-20-ft-1500-PSI-Stainless-Steel-Ice-Maker-Connector/3190901
in theory this would be much easier to roll into a small diameter coil and would certainly be corrosion resistant, however im sure the heat transfer rate would be much lower than just a SS pipe. Still looking for any input on this, it would seriously make my setup soooo much easier if i can just use the chilled nute solution rather than run a separate res for the chiller.

Im a little disappointed this thread has 50 views and no one has even chimed in
Just thought id post a little update and let you guys know that i found a place in my town that does tube fabrication, unfortunately they're closed this weekend including monday (memorial day weekend) but on tuesday im going to call them up and see if they're able to make me a tightly wound SS coil tube to use as the heat exchanger in the inline duct, assuming they can this is the perfect solution to fit my needs and will allow me to use my nute water to cool the tent!

JackSkell said:

Im a little disappointed this thread has 50 views and no one has even chimed in
Just thought id post a little update and let you guys know that i found a place in my town that does tube fabrication, unfortunately they're closed this weekend including monday (memorial day weekend) but on tuesday im going to call them up and see if they're able to make me a tightly wound SS coil tube to use as the heat exchanger in the inline duct, assuming they can this is the perfect solution to fit my needs and will allow me to use my nute water to cool the tent!

Click to expand...

You can just do liquid to liquid. I've got a chiller, it chills water inside of an ice chest. There are separate pumps inside of the ice chest that pump the water that the chiller chills to my mother plant in a dwc bucket, and I've got an entirely separate loop that goes to my cloner. Both use stainless steel immersion chillers. This way no nutrient solution comes into contact with the coolant or chiller and all of the different nutrient solutions are kept separate.

A coil inside of a duct is a terrible choice, the surface area where heat exchange can take place is much smaller than a radiator. Get a radiator, build a shroud for it and attach your ducting if that's what you want.

Your chiller is going to be running all the time though, trying to drop intake temp by 5 degrees. So figure an extra 200 watts at least all day every day.

dstroy said:

You can just do liquid to liquid. I've got a chiller, it chills water inside of an ice chest. There are separate pumps inside of the ice chest that pump the water that the chiller chills to my mother plant in a dwc bucket, and I've got an entirely separate loop that goes to my cloner. Both use stainless steel immersion chillers. This way no nutrient solution comes into contact with the coolant or chiller and all of the different nutrient solutions are kept separate.

A coil inside of a duct is a terrible choice, the surface area where heat exchange can take place is much smaller than a radiator. Get a radiator, build a shroud for it and attach your ducting if that's what you want.

Your chiller is going to be running all the time though, trying to drop intake temp by 5 degrees. So figure an extra 200 watts at least all day every day.

Click to expand...

If you had read everything youd know that i dont have space for a separate rez just for the chiller, be it a ice chest or a bucket.. i dont have space, have to use the nute rez to pump through the "icebox" which is why i cant use a radiator, radiators are copper/aluminium, they corrode and leach, honestly at this point ive already figured out how this is gonna work and im confident it will work well and the chiller wont be on 24/7 because the way im routing the lines. thx for your non constructive post though!

JackSkell said:

If you had read everything youd know that i dont have space for a separate rez just for the chiller, be it a ice chest or a bucket.. i dont have space, have to use the nute rez to pump through the "icebox" which is why i cant use a radiator, radiators are copper/aluminium, they corrode and leach, honestly at this point ive already figured out how this is gonna work and im confident it will work well and the chiller wont be on 24/7 because the way im routing the lines. thx for your non constructive post though!

Click to expand...

Yeah I read everything. And yeah your chiller is going to be on all the time, sure you can set it to 68 or whatever but if your intake temp is 75 guess what, the chiller is going to try and keep the water at the set point because that's how they work.

JackSkell said:

If you had read everything youd know that i dont have space for a separate rez just for the chiller, be it a ice chest or a bucket.. i dont have space, have to use the nute rez to pump through the "icebox" which is why i cant use a radiator, radiators are copper/aluminium, they corrode and leach, honestly at this point ive already figured out how this is gonna work and im confident it will work well and the chiller wont be on 24/7 because the way im routing the lines. thx for your non constructive post though!

Click to expand...

I'm just trying to help you man, you're going to end up wasting money on something that isn't going to do what you want. No need to get all bent out of shape because someone on the internet is telling you things you don't wanna hear.

If you have space in your room for a chiller you have space for a reservoir. Just put the chiller on top of it. They take air in the front and exhaust it out the back. They make a fair bit of heat doing it so if your room is closed you should plan for that.

Why can't you just run glycol through the fan coil and put the stainless tubing in the res, keep the system closed. Also if there is a HVAC wholesaler you can get coopernickle heat exchangers that will handle the nutrient water. Without a buffer tank you may run into short cycling as well. How big is your Res?

Way too much effort just to scrub 5F off the air temperature
I think dstroy`s advice is good. The chiller could run constantly and it wont make an ounce of difference.

lmao you people act like im tryign to cool 50,000sq ft.. you dont have enough info about my system to say what im trying wont work, and you know what this thread had over 75 veiws before either of you came along "trying to help" so why dont you just crawl back under your rocks now and let it go, as i said i know what im doign ill work, if you disagree its because you simply dont have all the info. good day.

Actually depending on the size OP may have an issue with short cycling as opposed to running all the time, which in it self is not a bad thing if temps are being met. The priority is the res with that being the temp control unless zone valves are added. OP these guys are actually trying to help so maybe provide the info that is required so yes we have all the info, you seem kind of angry lol.

Im not angry, just dont like people who think they know-it-all and then dont even offer constructive solutions. The tent im doing this on is a mere 44sq ft and temps rarely go above 80, i use LED lighting so they hardly heat up the room, my intake is drawn from outside and as we get into hotter months i may see up to 85 inside the tent, hence why i only need to cool about 5 degrees. As i stated in the OP my lines would go from rez>icebox>chiller>rez. and the rez is 30gal insultaed. my water stays at 72 degrees in the rez without a chiller right now, so im fairly confident i can set the chiller to 65 and it will keep it there without running very often, im absolutely aware that this may not be the most efficient way to achieve my goal but i am also quite confident it will work and will fit MY needs which is all that matters.

JackSkell said:

lmao you people act like im tryign to cool 50,000sq ft.. you dont have enough info about my system to say what im trying wont work, and you know what this thread had over 75 veiws before either of you came along "trying to help" so why dont you just crawl back under your rocks now and let it go, as i said i know what im doign ill work, if you disagree its because you simply dont have all the info. good day.

Click to expand...

I guess you`ll just have to find out the hard way, we`re just trying to save you from wasting your time. Work out the airspeed in the duct and then you can figure the contact time of the air with your stainless steel coil..it`ll be micro seconds. You could put a cup of ice in your duct for a quick and dirty test, it`ll have more surface area than the SS coil and a lower temperature..but it still wont make a ounce of difference to the air temperature.
Some of us have real systems running upto 1000cfm that dont involve chillers or SS coils but can still scrub 20F-30F off the air temperature.

Well like I said your primary target is the res. I assume you will be cycling the chiller on res temp. so yes it may short cycle, you'll have to put a fairly large delta t in there to let the chiller run properly, perhaps 4-5 degrees. With a closed system you could put two circuits in, that gets complicated though lol. So really what ever you get out of the air coil is dependant in the res run times and that may not be enough but hey it's there so why not try I guess. The biggest issue you will have is short cycling I would think, the air cooling is what it is but yes a finned coil would be the better choice , you know that though.

Atomizer said:

I guess you`ll just have to find out the hard way, we`re just trying to save you from wasting your time. Work out the airspeed in the duct and then you can figure the contact time of the air with your stainless steel coil..it`ll be micro seconds. You could put a cup of ice in your duct for a quick and dirty test, it`ll have more surface area than the SS coil and a lower temperature..but it still wont make a ounce of difference to the air temperature.Some of us have real systems running upto 1000cfm that dont involve chillers or SS coils but can still scrub 20F-30F off the air temperature.

Click to expand...

lmao if youre not here to be constructive then just gtfo man.. you clearly still aren't following the fact that this fits MY needs, i dgaf if it would never fit yours, it will fit mine, and im having a custom coil made which you have literally ZERO idea of what the surface area will be so im not sure where you get off thinking you know anything about a coil you've never seen before.. good try though asshat, you're excused.

Budley Doright said:

Well like I said your primary target is the res. I assume you will be cycling the chiller on res temp. so yes it may short cycle, you'll have to put a fairly large delta t in there to let the chiller run properly, perhaps 4-5 degrees. With a closed system you could put two circuits in, that gets complicated though lol. So really what ever you get out of the air coil is dependant in the res run times and that may not be enough but hey it's there so why not try I guess.

Click to expand...

budley thank you for being the only person here with constructive posts. i wont be replying to this thread anymore as its clearly just becoming a place for the people with "real systems" and know-it-alls to shit on others ideas.

What a muppet i`ll look forward to seeing your theory fail in epic fashion, thats assuming you even get as far as building it

JackSkell said:

lmao if youre not here to be constructive then just gtfo man.. you clearly still aren't following the fact that this fits MY needs, i dgaf if it would never fit yours, it will fit mine, and im having a custom coil made which you have literally ZERO idea of what the surface area will be so im not sure where you get off thinking you know anything about a coil you've never seen before.. good try though asshat, you're excused.

Click to expand...

"Constructive criticism is the process of offering valid and well-reasoned opinions about the work of others, usually involving both positive and negative comments, in a friendly manner rather than an oppositional one."

I'll just leave this here. Everyone was trying to help, not saying that putting a coil in a duct wont work, but it wont work well.

It will probably need to be pretty large, due to it's low thermal conductivity in comparison with other choices.

316ss tubing (food grade, obvious choice) thermal conductivity is 17 http://www.azom.com/properties.aspx?ArticleID=863

just for example, the thermal conductivity of aluminum is 237, copper is 401

What those numbers mean is that any heat exchanger built out of steel is going to be orders of magnitude less efficient at removing heat than other material choices. That doesn't mean that stainless steel isn't a good choice for the application you want, it means that it is going to have a much larger surface area to do the same job.

I understand that you don't want to run nutrient solution through aluminum or copper, which is why I suggested liquid-liquid. The reason I suggested liquid-liquid is because stainless steel is a poor conductor of heat, and the exchanger surface area required is going to increase substantially (be way more expensive if you are using bare tube) when you cool liquid-air.

You want the most surface area possible when attempting to cool air, which is why radiator tubes have fins brazed to them.

I asked for constructive solutions, not for criticism of any kind, as ive stated repeatedly i understand this is not the most efficient way to do it, but i dont need the most efficient way of doing it, infact using the most efficient way would cool way more than i want it to, so using a less efficient system FITS MY NEEDS which seems to be the point you people cant get through your skulls. Im glad you guys have "real systems" and love spending more money than necessary but im not about that life im a simple self supply and hobbyist grower so try to understand that i dgaf about having the "best" system, it just has to work FOR ME. and as i told you before i dont have space for an additional reservoir, the chiller is already sitting ontop of a small table with other things underneath it, there is no space available for anything else in my room dude, ive gone over the different possibilities, ive stated what will fit my needs, and yet instead of trying to help me find a way to make it work you all just want to tell me im doing it wrong and then tell me to do it the way ive already told you wont work for me..

And since im repeating everything else ive already said let me reiterate "custom coil" you cant even begin to put a basic picture of this in your head because it will be unlike any other coil out there, that is what custom means, and for all you know i could have it built to be the most effective ss coil in the world, im not saying i will, just saying that the reality is you have no clue about it so you really cant say it wont be as effective as a copper coil- you can state the thermal conductivity numbers as you already have- but just because copper has a higher rating doesn't mean a slightly larger stainless unit cant be built to cool just as well as a smaller copper unit, and the ducting is already there anyway so what do i care if the ss unit has to stretch the whole length of it.. its gonna be out of sight anyway same as a copper one would be.. as far as the cost even if i have to spend 500$ on it it would still be cheaper than purchasing a seperate rez, a wort style chiller for the nute rez, a HI icebox, electronic watergate valves and temp controlled rheostats to keep everything in check with the temps i want, yea all that shit adds up to over 600$ easy.

In closing- instead of "helping" people by telling them whats best for you, maybe you should actually pay attention to their specific needs and make suggestions that fit within their needs.

JackSkell said:

I asked for constructive solutions, not for criticism of any kind, as ive stated repeatedly i understand this is not the most efficient way to do it, but i dont need the most efficient way of doing it, infact using the most efficient way would cool way more than i want it to, so using a less efficient system FITS MY NEEDS which seems to be the point you people cant get through your skulls. Im glad you guys have "real systems" and love spending more money than necessary but im not about that life im a simple self supply and hobbyist grower so try to understand that i dgaf about having the "best" system, it just has to work FOR ME. and as i told you before i dont have space for an additional reservoir, the chiller is already sitting ontop of a small table with other things underneath it, there is no space available for anything else in my room dude, ive gone over the different possibilities, ive stated what will fit my needs, and yet instead of trying to help me find a way to make it work you all just want to tell me im doing it wrong and then tell me to do it the way ive already told you wont work for me..

And since im repeating everything else ive already said let me reiterate "custom coil" you cant even begin to put a basic picture of this in your head because it will be unlike any other coil out there, that is what custom means, and for all you know i could have it built to be the most effective ss coil in the world, im not saying i will, just saying that the reality is you have no clue about it so you really cant say it wont be as effective as a copper coil- you can state the thermal conductivity numbers as you already have- but just because copper has a higher rating doesn't mean a slightly larger stainless unit cant be built to cool just as well as a smaller copper unit, and the ducting is already there anyway so what do i care if the ss unit has to stretch the whole length of it.. its gonna be out of sight anyway same as a copper one would be.. as far as the cost even if i have to spend 500$ on it it would still be cheaper than purchasing a seperate rez, a wort style chiller for the nute rez, a HI icebox, electronic watergate valves and temp controlled rheostats to keep everything in check with the temps i want, yea all that shit adds up to over 600$ easy.

In closing- instead of "helping" people by telling them whats best for you, maybe you should actually pay attention to their specific needs and make suggestions that fit within their needs.

Click to expand...

Ok have fun with your "custom coil" that's not like anything I have ever seen. Even though I was willing to sit down with you and help you through the math to figure out exactly how big it needed to be I guess that's not helping you.

Yeah. You sure wanted help. I can tell that now.