An additional line of thought. Cooling radiators in summer?

I found this having the same concept for cooling. I live in south louisiana, US where 95F is vary common turning tin boxes into a slow cooker. I am going to build a decent shop for all my automotive, and construction tools.

The concept I had was some large truck radiators for a couple of non load-bearing walls and either use some city water to run through them, cooling the shop a touch and heating my water some before hitting my home water lines, or use the canal on my property with a water ram pump.

I acknowledge the potential multiple metal types causing issues and the need for a filter for the canal water and depending on the radiators I get if I go the other route a filter before the water gets near the house.

My city water right now is coming out the ground at 79F, Canal water at 76F, at noon. Ambient direct sunlight temperature of 85 sheet metal indirect sunlight 100 degrees.

Any points of interest or concern that have not already been mentioned?


You need insulation a looooot more than you need active cooling. Think "ounce of prevention, pound of cure".

The main source of your heat is not ambient air. It's solar load, and there's your Google word. The solar load, by itself, will have a "Bridge on the River Kwai" effect - and if this is still not clear to you, sit in a car in the direct sun, engine off, A/C off, fan off, windows rolled up, until it becomes clear to you. Which it will rather directly. This effect can drive in-structure temperatures to 120, even 150 degrees.

That is why solar load is so darned important. If you can keep the sun completely off your building, you can dispense with most of the heat input. Then, you only have to contend with ambient heat (the kind you already think is the problem) - and that might not be so bad.

One flaw in your "cooler water into radiators" scheme is you will get condensation on the radiators, and that water will drip down below wherever the radiators are. You will have to remove it from the building unless you like puddles and water damage. That is why there's no such thing as floor cooling.

Also, thermal mass (inside the insulation envelope) is your friend. Think about it.

Really, you would be better off setting up a "mini-split" or a marine A/C pack that would allow you to interchange heat into canal or city water. It's easier pumping heat downhill than up, and a 150 degree F condenser coil will perform much better in 76 degree water than 120 degree heated air from the condenser being in direct sun.

  • 1
    Concur - the single best thing is to paint the roof white, then the outside walls. Also, no running costs.
    – Criggie
    Aug 13 '19 at 9:56
  • 2
    I'd even put a white shade roof panels gapped significantly above the actual roof. Aug 13 '19 at 16:26

There are air conditioners using sea water, rather than a heat pump, but that works because ocean water is usually well below 10° C (50° F). Using a canal would be less corrosive, but you'd need a heat-pump to get useful cooling. Some examples of air conditioners using sea water to cool the condenser are at Flagship Marine.

That said, you'd need to check local regulations for use of the canal water.

As has been mentioned, though, making the workshop fairly air-tight and well insulated is necessary before you install air conditioning, or you're pouring money for the air conditioner and the electricity to operate it out the window.

Solar panels on the hot tin roof would help to shade the building and run the AC, too.

  • These are readily available for marine application, and good news, the salt water side is intended for dirty brown/green water, because that's where most hobby boats spend most of their time. Brown=rivers/canals green=littoral(coastal) Aug 13 '19 at 16:22

Just get the proper sized window a/c unit. Modern window units are cheap and efficient.

Do regulations allow one to pump water out of this canal and then return it to the canal warmed up?

Using city water will not work unless you could keep the water running constantly.

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