Water Cooled Grow Rooms

PC, I read every post in this thread and there was only one reference from someone that they buried a coil. As you say, maybe there was more before the dump. I have maybe 3000-4000W of lights to cool. Separate Veg and Flower rooms. Doing soil so no res. No CO2. Just the lights and ballasts. In a basement.

I could easily sink some coils and circulate the 55F coolant through the system, but don't know if it would be effective connected to a radiator. Some of my warmed air in the grow rooms would be blown into the rest of the cooler basement, and I would also pull the cooler air in as supply air for the grow rooms. The geothermal idea was to simply augment that.

cerberus said:

55 is the right temp. i thought we had talked about geothermal heat sinking before, but i guess not.

I have thought about adding a geothermal unit to my cooling (I'm building a house that has a geothermal heat sink compenent, w/ passive solar and wind), but for me, i'm hoping my giant rez burried 10 ffet in the ground will act a s ageothermal heat sink.

great topic, good call.


green hell, its cheaper

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You and I are in the exact same boat. I'm looking at all of these energy sources also.

Gyroscope said:

Hello phillipchristian,
This is a very interesting thread. If a person wanted to try geo thermal, what would be better to bury - coils, a holding tank, or runs of pipe ?

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Hey Gyro, welcome to the thread. I really think it would depend on ambient temp where you live and what kind of heat load you were trying to take out of your room. If you were doing a small load like 1-2 lights then I think coils would be best but if you were trying to do a large load that included cooling ambient room temps then I think you'd need a tank. Like I sad though it will depend on other factors.

cerberus said:

55 is the right temp. i thought we had talked about geothermal heat sinking before, but i guess not.

I have thought about adding a geothermal unit to my cooling (I'm building a house that has a geothermal heat sink compenent, w/ passive solar and wind), but for me, i'm hoping my giant rez burried 10 ffet in the ground will act a s ageothermal heat sink.

great topic, good call.


green hell, its cheaper

Click to expand...

A bunch of it got erased with the hack. Budley had put up some cool info but I guess it got erased.

I think with Geotherm, it's better to run field loops, like you put in a septic field, but deeper. The ground is a big sink and if you change the temp of a smaller mass like with a buried coil,the soil mass tends to go to the average temp of the coil. Now the soil is an insulator. A big tank is different. Then water mass is big enough to equalize itself to the earth.

So, coils are the opposite of fields. Coils are for low mass quick change like beer wort. Fields are for long run, slow change over a large mass. However, there is nothing to say the "field" can't be vertical.

This a 4 line vertical field 150 feet deep. It's a whole house system in Canada. So, it's pretty easy to calculate the need per watt to sink. 3 lines, 40 feet deep might be plenty?

I just thought of a great Idea!!! I'll share it with youse first. I've been wondering for a long time how to use the cold city water. I just removed a solar system that was pre-heating the hot water heater. Panels were bad, but the plumbing is still there.

Here's where a simple coil can be used. For me, I would plump the city water entry thru my light res first before the hot water heater. That way any usage of water in the house, cools the res AND saves the heat into the hot water heater. Pretty cool, huh? That's a green approach. That why I like this forum. I get ideas.

There may be places, like Dallas, where the city water is too warm in summer. Also, DIY pool cooling in Dallas summer is where i got the idea of min-cooling towers if you are using a hot tub as a heat sink.

Doer, I like your idea a lot. Very smart. I don't use a res, but perhaps there's a way to do some of this with what I'm doing. I will have to investigate.

I've been reading up on geothermal. Fascinating. I'm looking at having geoT installed for the house, so I'll have a component run over to the grow rooms. Still venting into the rest of the basement, but I'll have the basement on it's own zone so if it gets warm, the main house system will compensate.

Would 55F water passing through these light cooler tube systems do anything, or is that a futile effort with minimal gains?

55!? I work with 62 min to 78 at lights out 1000w, 100gal, 12 hr cycle. At 55, the world is your oyster! Condensation on the light tube can be a problem. But, that indicates the room humidity is too high, I think.

I'm assuming my deep soil temp where the coils would be is 55F. Aren't these light cooling sleeves running chilled water? Like 40F or such?

I think you guys are talking about heat exchangers and Ice Boxes. You could use 65 degree water in these things to remove heat from your grow room. The only concern is the tubing that you use to supply them. You have to use a dewpoint calculator to see what is the minimum temp you can have in your water withough creating condensation on your lines. Usually, depending on your humidity and room temps, it falls somewhere between 58 and 65 degrees. If your water is below dewpoint then you are going to have a lot of moisture on your supply lines which is a huge problem. My chiller has 2 reservoirs and pumps built in just for this issue. 1 reservoir is kept at 45 degrees and feeds the air handlers via tubing that is plumbed from the outside so condensation is not an issue. Tubing runs underground, then up the outside wall of the building and then through the wall and into the air handler. The other reservoir is kept at 58 degrees because it actually supplies manifold lines which run through my room to wort coils, Co2 generators, dehumidifier, and a few Ice Box I have for supplemental cooling in spot areas.

So fluid circulating through the light sleeves, etc is above the dew point. So the geo-cooled water may in fact have to be warmed slightly

Rrog with heat exchangers and air handlers the water can be as cool as u want because condensation will not be a problem but with ice boxes you want to make sure those are above dew point because they are attached to your hoods and you don't want condensation around your lights.

Well, I'm talking about primary sink. It's 100 gal, black, in shade. It wouldn't freeze at the winter temps we get. It radiates at night so the morning temp is back to 62-63.

No need to run 40F in the sleeves. And that would place a 40F spot of descending cold air over the plants. In the summer, it would be nice to run a 55F ground surface loop, under the house, but, I'll use a secondary sink and cooling tower.

Rrog said:

So fluid circulating through the light sleeves, etc is above the dew point. So the geo-cooled water may in fact have to be warmed slightly

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No need to use geo-therm in the primary loop. A lot of this is about mass volumes, flow rates vs surface areas, etc. Safe to say a heat exchange into the ground loop is all your primary sink needs. Primary could be just 20 gals, maybe.

NickNasty said:

Rrog with heat exchangers and air handlers the water can be as cool as u want because condensation will not be a problem but with ice boxes you want to make sure those are above dew point because they are attached to your hoods and you don't want condensation around your lights.

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Hey Nick. Ice Boxes are heat exchangers. Secondly you need to be worried about dew point on anything (sleeves, ice boxes, Co2 generators) that is water cooled and in your grow room. Condensation on equipment and supply line is a primary concern. Whether it be the manifold lines, an Ice Box bein used as a spot chiller, or even a wort coil; you need to keep that water above dew point or you will have issues.

Doer said:

Well, I'm talking about primary sink. It's 100 gal, black, in shade. It wouldn't freeze at the winter temps we get. It radiates at night so the morning temp is back to 62-63.

No need to run 40F in the sleeves. And that would place a 40F spot of descending cold air over the plants. In the summer, it would be nice to run a 55F ground surface loop, under the house, but, I'll use a secondary sink and cooling tower.

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do yourself a favour and burry it. if you put it at the frost line you have essential a can sellar which is a constant 50ish degree's. yo'll have the added beni of the thermal mass of the earth around it, rather than just free standing.

cerberus said:

do yourself a favour and burry it. if you put it at the frost line you have essential a can cellar which is a constant 50ish degree's. yo'll have the added beni of the thermal mass of the earth around it, rather than just free standing.

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I would, but, I'm adverse to digging. Actually, It's far, far from a cellar. It's a very low, belly crawl space. And what they call a residental lot around here, forgetaboutit. At least I'm not in an association, with restriction, but it would be a problem to bring in.....well, there are those two man augers.
We don't have a frost line more than a couple of inches;.o

I could just sink the primary 3/4s into the dirt. That would keep it from gaining from OATemp. Then with the city water plumped thru.....
probably worth the digging. thanks.

I can dig the trench 5' deep and use standard domestic geothermal materials. Methanol + water or such. I'll do some component for the house while I'm at it to spread out the costs. Ultimately, that's one hellova resource that I can't ignore.

You are right about that. And the way these utility bills are going, every little bit counts. The wife has nixed solar and wind, for the visual degradation, but, it might be part of an all sources plan in the future. I used the rebate to put in a super-high efficiency, HVAC, but still, with the rate tiers.....<sob>

I found this DIY rig. He made a water drill, went down 13 feet, I guess, then trenched between.
http://ecorenovator.org/diy-ground-source-heat-pump/

I suppose there are on-line calculators to size these efforts. Happen to know any rules of thumb?

I've dumped solar and wind due to the overly-lengthy payback. A DIY Geothermal pays for itself much sooner.