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Water Cool your garden

Let’s talk water cooling for your garden. First the disclaimer. With any badass tech from solar, wind, and hydro power, to led lighting and water cooling you have to pay the up front costs to save money down the road. My water cooling set up cost me about 3 times as much to buy compared to a conventional air conditioner mainly in insulation. It also costs half as much to run though. For a person with a pocket full of money who only cares about staying under the radar of the power company it’s a no brainer for me.



Water cooling your garden requires a chiller, a seriously insulated water reservoir, heat exchanger/s, inline fan/s, water pumps, and some seriously insulated tubing. Yes, a chiller and air conditioner are the exact same piece of equipment technically. One has air passing over copper coils filled with freon and one has water. Knowing that, cooling water is more than double the efficiency of cooling air. I have over the years managed to get a 3 ton commercial chiller to cool not just my garden/s but, my entire building to uncomfortably cold. I first looked into water cooling in the late 90’s for computers when a few years later I realized it may work for cooling my garden.


Heat Exchangers

Water cooling and heating with heat exchangers has been used for a lot longer than any of us reading this have. Engines in cars, ships, and planes use heat exchangers to work more efficiently too. I thought I’d explain some of the things I’ve learned from my 10 plus years running them. I recommend people buy or make heat exchangers. I’ve made my own over the years. Hot air come’s in and cold air comes out. They transfer the heat from the air into the water flowing through the coils/metal fins of the heat exchanger. Hydro Innovations is a company that make’s many different sized heat exchangers you can buy off the shelf. Their least expensive model is called an Ice Box. If you buy one of these and ask how to install it they will tell you the most inefficient way to do so. The way they’d have you do it won’t help pull humidity and has you dumping all the heat from HID lighting into the system. They don’t want you running very cold water. WTF, I’ll explain in a minute why this is unwise. My heat exchangers pull at least a 5 gallon bucket of water a day out of my room/s the way I use them. They come with drains for a reason. I’ve been in the process of stripping out all my hps lighting and going led using Spectrum Kings so my life just got a whole lot simpler. The Ice Box instructions show a picture of the setup dumping all the heat from the vented HID hoods through the Ice Boxes to remove the heat. No thanks, they create a ton of condensation if you run your water cold. I like to keep water and condensation off my glass and BULBS. Small setups could put the heat exchanger at the end of the run so no condensation would get near the hoods. The only reason to do this would be if you have no way of venting heat from the hood/s out of the room. It would be inefficient but safe from flir detection if pumping heat out of the building is not an option for larger setups too. They recommend you not run cold water to prevent condensation. If you constantly dump a heat load from HID lighting into the heat exchangers, your chiller will not shut off or cycle properly. The whole point of water cooling is to be more efficient than conventional air conditioning. When was the last time you heard of anyone dumping HID bulb heat into their a/c return? Not now, not neva, no ways. If you draw air from outside the sealed room through vented hoods and exhaust the heat from the lights out of the room like anyone with more than 2k running does you could cool 20k in HID lighting and keep the room at 60 degrees if I want with a 3-4 ton chiller. It would take a 4 ton a/c to keep half of that wattage cool. General rule of thumb for the tent guy is a 1/4 hp chiller (about 400 watts) can handle 1000 watts of hps/mh bulb heat. Vent some/all of the 1000 watt’s heat away and your golden, but the math only scale’s so far and it take’s a whole lot of knowledge or trial-n-error like I had to go through, to be robot efficient. Sorry HVAC guy your math for cooling air means nothing to cooling water. When sizing for an air conditioner, the rooms square footage and HID lighting wattage is used in a formula. When sizing a chiller for a grow, the water volume (res. size) is what’s important. Think of my cooling system like a mini split a/c. My chiller is far from the grow room chilling a 100 gallon res. The chillers only job is to keep the res at 40 degrees. My chiller can take 100 gallons of water at 80 F and drop it to 40 F with the system running in about 1 hour as long as I’m not pulling heat from the lights into the cooling system. If I was doing that, the chiller would run all 11 or 12 hours the lights are on like most people have to deal with their a/c. My chiller cycles normally running about 5-10 minutes on and shutting off for about 15-20 minutes while the lights are running and maybe run 10-20 minutes total at night. The heat exchangers, inline fan/s, and some tubing are the only part of the cooling system in the grow room and are not removing heat from any lights that would make the system inefficient. That heat should be vented away like any smart grower does anyway. Now my “cooling” comes from little box’s with cold water running through them. When my environment controller turns on my “a/c” a 200 watt Can Fan and eco-plus 633 gph water pump turn on. My power bill is half what other growers in my area pay for my light wattage and I crop more weight because i can run more lights efficiently using the same total power. The set up is pretty easy to explain. You have a chiller with two water lines running into a reservoir. One for intake and one for exhaust. A pump in the reservoir flows water constantly in a cycle to and from the chiller 24 hours a day. The chiller has a thermostat and can cycle on and off as needed. Separate pump/s in the reservoir send cold water through lines to the heat exchangers which have an inline fan pushing (pulling will pull water into your inline fan) air through them, then sends the warm water back to the reservoir hopefully on a thermostat in the grow that controls those pump/s and inline fan/s that provide the cooling in the garden. Feel free to ask any questions since I only briefly went over setting this system up. Just remember to keep buying insulation. There is no such thing as too much. Growers

I just moved and here is a picture of my reservoir filling up before I had water lines or chiller hooked up. The reservoir is 2 feet in diameter. With the insulation it’s now over 3 feet wide. 😉