How efficient would it be to use radiators circulating with cold water, to cool house in summer?

Wondering if anyone has tried this, and how well it works?

I was thinking about H/AC in general, and wondering if it is possible to to leverage my actual system to get cooling in particular...

Anyways, all I could find was this, but it's advertising a service so not really credible in and of itself.


I think you'd end up running into a whole boat load of issues before you could even begin talking about efficiency. The first and most pressing being the rapid condensation that would occur within seconds of circulating the cold liquid (leaving you with a whole host of other DIY problems you'd need to work out). Which, I imagine would need to be somewhere between 20-60F below the ambient temperature of the air to get any significant cooling effect.

As for efficiency directly, if what I learned in PHYS160 about thermodynamics holds up, it should be exactly as efficient (heat transfer wise that is) as the radiators are at heating the air. But I HIGHLY suggest getting a second opinion from someone more versed in HVAC work, as the closest I've come to directly researching this is looking at data center cooling technology.

**More on datacenter cooling: http://searchdatacenter.techtarget.com/feature/Modern-data-center-cooling-systems-No-muss-no-fuss-no-waste

  • 3
    +1. Condensation on the plumbing would be a huge problem. – Tester101 May 30 '16 at 13:18
  • great point, I had't considered the condensation. So I'd probably have to run a dehumidifier as well... – MediaFormat May 30 '16 at 14:37
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    A dehumidifier that could pull the water out of the air before the cooling radiator can get it would be more powerful than a window AC unit. -- TV columnist Hugh Downs used to refer to this sort of thing as "nested technological redundancy". – A. I. Breveleri May 30 '16 at 15:11

You'd need a closed system with a serious dose of antifreeze to get cold enough for significant cooling. Radiators usually run at least 40C above the desired room temperature to provide heat. To get the same amount of heat transfer into the radiators for cooling, the circulating water would have to be as cold as a freezer (-20C).

Possibly by running 24 hours a day you could run at just above freezing point, but then you'd still have to worry about icing up in your water chiller.

This in on top of the condensation problems mentioned already (which would be worst where you couldn't deal with them - e.g. water condensing on pipes below the upstairs floorboards would drip onto the ceiling below).


This is unconventional for a residence but it will work, although not quite as efficiently as the heating in winter.

You will need a source of cool water. If you have an artesian spring on your property or a stream running through it, the project might be worthwhile. Otherwise you will need to install a chiller, and you may have trouble finding a HVAC professional willing to be associated with it.

Because of the natural temperature gradient in most rooms, the radiator (which is near the floor) sits in a bath of cool air. During winter heating this results in efficient heat transfer and drives circulation through convection. For summer cooling this is less effective, so you will need to add a circulating fan to each radiator.

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    HMSCelestia is correct -- you will also need pans and drains to collect the condensation. – A. I. Breveleri May 30 '16 at 6:27
  • It would be best to edit this information into your answer; to my mind this is the most important aspect to the problem. – Daniel Griscom May 30 '16 at 12:32
  • thank you, I was wondering about the radiance of cold vs. hot, the convection is an important point as well! – MediaFormat May 30 '16 at 14:38

M-Cycle heat exchangers allow you to cool your house using a radiator, water, and fan only. Look up the research and even the products in the market.

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    Welcome to Home Improvement. Please disclose any affiliation with the company. Presuming you're not just advertising, if you'll take the tour you'll note that we look for good quality answers, so just suggesting that someone go look something up isn't particularly helpful. Why don't you provide some of the research with links to sources so folks can do additional research. – FreeMan Apr 6 at 15:06

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