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Radiant cooling

We recently read that radiant heat in the floor can be converted to cooling by running cool water through the lines during summer months. Does anyone know anything about this?

Re: radiant cooling

First I've heard of it, but I don't see why it shouldn't be possible. You'd need extra valving to switch to the cool water, and of course a source of cool water. It may require flushing the lines between switchovers. If your radiant heating uses a coolant instead of water, you'd need to use a heat exchange unit instead of switching to cool water.

You'd probably want to talk to Richard Trethewey on this one ;-)

Re: radiant cooling

I haven't heard of radiant cooling. It is an interesting concept. I would also be curious to know about this if available.

I have been doing some research on geothermal heating/cooling systems. The preferred method of heating in geothermal systems is through radiant methods. However, the cooling process is done throught a "hybrid" type system that uses the same idea, but uses forced air to deliver the cooling through ducts.

Re: radiant cooling

In most cases I do not think that this will be very efficient. In some installations then condensation could become a serious problem which would have to be monitored very carefully.

Re: radiant cooling

I looked into this at one time. What I found out was that condensation would be a major problem. If you warmed the water temp up enough to reduce the condensate then you severely reduce any cooling effect. The other problem with this type of cooling would be any "cooling effect" would be below knee level due to stratification unless you continulously ran fans to prevent this. This problem with cooling is the exact reason that floor radiant heating works so well! Heat rises!

Re: radiant cooling

If you had a heat (cool) sink colder than your floor already, pumping a colder fluid through the floor would most likely cause major condensation problems resulting in very wet floors, a very undesirable effect.

Re: radiant cooling

If you have radiant heating you might want to consider a split-type air conditioning system like Rich Trethewey installed on episode 426 of Ask This Old House. It's kind of like a really nice window air conditioner with the noisy condensing part of the unit outside. You don't need a forced air system to use this.

Re: radiant cooling

I am not an HVAC contractor but I believe one of the most important aspects of an air conditioner is to remove moisture from the living space. Many people put in a system or even just a window unit that is to big for the area. It will cool the air to fast and will shut off before it can dehumidify the area and you will get that cold clammy feeling. With a radiant cooling system you would not be removing the moisture from the air and at best your house might feel like a damp basement cool but wet or at worst you could end up with water damage. I hope this helps you out.

Re: radiant cooling

Thank you for all the replies. I can see where condensation could be a problem and with yellow pine flooring it may cause mildew. We already have enough problems with moisture since this is an 1820 stone house with a spring in the basement. We have eliminated this as one of our cooling options. Thanks again.:)

Anonymous (not verified)
Re: Radiant cooling

Hi...most of what is said here is absolutely correct but to recap some of the correct highlights.... Sending cooling water within radiant floor tubes will most likely cause moisture/mold problems caused by condensed moisture from humidity. The most effective way to cool the house (especially if you have heating by hot air) is to install a split AC system with an "A" coil in your hot air system plenum. If you don't have hot air heating, high velocity A/C systems are an option as they don't require large ducting. Also, through wall splits are also a good option for new installation in older houses. Any HVAC contractor can look at your house and give you recommendations as to the best and most cost effective way to A/C your house. Make sure you have a system with a high SEER rating...the cost will be higher upfront but the pay back is worth it. Also, systems with scroll type compressors are higher in efficiency and also quieter. Also, check with your electric utility provider...they may offer rebates for system with a certain high SEER rating.

Good luck!

Re: Radiant cooling

Don't give in just yet till you hear both sides: First of all, heat doesn't rise, but hot air does, and thats a big difference when it comes to radiant heated floors vs scorched air heating systems...the comfort level of a radiant floor is Nirvana compared to the convective drafty currents of hot air blown in thru vents over your head only to collect at the ceiling. Radiant floors are like the sun. Conversely,....cold doesn't fall, cold air falls, which is why radiant cooling in the ceiling makes more sense and successfully and uber-efficiently done over in Germany. To get around the damp/moist factor, they employ window sensors that simply adjust temp of the water running thru the ceiling panels so that the aluminum ceiling-panel system (or concrete ceiling) "coldsink" doesn't sweat nor worsen the humidity inside. Radiant cooling is a brilliant idea since less energy needed for the few times a day the air is recirculated thru much smaller mini-duct system to circulate and dessicate the air. Apparently, the cost savings can be over 50%....but, its that startup cost as with any high-efficiency system that keeps us from practicing what we preach. Until we pay what the Euros pay for energy, the majority of installs for new construction will continue to use poorly-efficient and outdated methods of heating and cooling. But the radiant cooling system is here and it works. Very 'green', uber-efficient, and probably the right way to go if you can afford it. And yes, wouldn't it be great to use the existing radiant system already in the floor.....all I know is that hot air rises (Not heat) and cold air falls.


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