Hydronic cooling.

Rollie Peck

Hi Guys:

Have any of you installed or experimented with hydronic cooling? Pipes buried in the ceiling? Finned tubing on the walls near the ceiling? Seems like it would have some advan-
tages for those of us who prefer hydronic heat over scorched air. Am aware that cold surfaces will condense the moisture from warm, humid air.

Rollie Peck, homeowner.

Weezbo

Rollie....

heres a cool site to go visit ..KaRo in south of France....really i highly respect their work and there is a choisce of english french or what most people speak available on thier site. just take the time to peruse thier offerings and technical information ... and i am sure there will be ample time to find some educated and experienced replies after you have had a chance to get some very accurate knowledge and insights from thier site ...

Constantin

Take a look at...

....Natural Cooling's Web Site. They are the US reseller of the KARO system and seem eager to get systems installed.

Weezbo

Well done Consantin *~/:) enough inquires produces this availab

in good ole U.S. of A. *~/:)

GMcD

Actual operating examples

There are a growing number of actual operating radiant cooling systems in North America: Green on the Grand by Enermodal Engineering in Ontario opened in 1996, Earth Rangers Conservation Centre in Ontario from 2004 (another Enermodal job), Gleneagles Community Centre in West Vancouver designed by Earth Tech opened in 2002, ICT Building at the University of Calgary designed by Earth Tech opened in 2001, Pier One radiant floor cooling system in San Francisco, activated in 2000, plus many more suspended radiant panel projects and smaller scale residential projects with radiant heating/cooling systems ( www.ourcoolhouse.com ).

I've been involved in some of the above projects plus a couple of current projects as the design engineer. Nothing scary about it at all. Laws of Physics in action, Stefan/Boltzmann and all that. My forte is large scale commercial/institutional systems, but the issues are the same - the building envelope is an integral part of the mechanical system and it's performance, that is the first intensive effort- design the building envelope to properly suit a hydronic radiant system in the first place, and the rest is easy.

jerry scharf_2

What to do with the humidity

Geoff,

I'm really glad you're here. I thought about doing this but shied away for my project. One of the critical aspects of the project is keeping the house at very low mold levels (as mold free as I can do.) My target RH is 40-45% and try to never go above 50%. I specced an A/C system that has excellent humidity removal ability. As an aside, since there is large airflows to mecahnically filter the air (3-5 ACH), moving the air for A/C is no extra cost.

I would think with radiant cooling you would start to get humidities at fairly high levels. How is this dealt with? If you need to run the air past cold coils to pull out the moisture, then what's the advantage of the radiant cooling?

I'm not being critical, just trying to learn more.

jerry

Weezbo

the advantage of radiant space conditioning ?

perhaps 6 700 $ a month depending upon where you live...:)...thats isnt an exact answer buh i am sure your understanding encompasses the idea that 80 degrees is preferable to 104...some large buildings use a variety of stradgies to move the heat where it will do some good and thats basically an incredible advantage over trying to sledge hammer the heat into submission with Huge compressors and tons of coolant....

GMcD

Humidity control

Jerry- humidity control is a big issue in climates where you can have extended hot, humid periods. Yes, you need to squeeze the humidity out of the air by a cold coil of some kind, and in some cases, re-heat it depending on the air quantities involved. If you can do all of your sensible cooling from a radiant cooling system, that reduces the net amount of air you need in your house to the reasonable minimum for healthy conditions and make-up air for exhaust requirements (bathrooms, showers, laundry, cooking, etc,). Normally the Code Minimum (where I am) is 0.5 ACH. For a healthy house with good humidity control and fresh filtered air, you might want 2 to 2.5 ACH in a radiant heating and cooling system scenario. Still a lot less air than a conventional "air conditioning" system that uses "cold air" to create cooling comfort.

OK, what about the energy use of reheat in a scenario where you need some cold cooling coils in the ventilation unit? - use the return water from the radiant system and in an HRV ventilator system, with the right controls setup, should be no problem doing a virtually energy neutral cooling/reheat system for dehumidification. See Robert Beans' site for the "perfect healthy home HVAC system" at: http://www.healthyheating.com/bb/viewtopic.php?t=51

Don't forget that a radiant cooling surface at around 63F-64F can put out in the neighborhood of 20-25 Btuh/SF of emitter area with a ceiling system (avoid floors since cold floors will lead to muscle fatigue and foot cramps), so that allows an indoor relative humidity level in the 55-60% range before you will start to get dewpoint issues.

The key is to design the building so your cooling loads inside the house/room are less than 20 btuh/SF so you don't need really cool radiant surface temps to get your required comfort cooling. If a radiant cooling system can be made to work in Bangkok, you can make it work in most areas of North America.

Some weblinks for further reading:

http://www.uponor.com/businesses/businesses_7.html

http://doas-radiant.psu.edu/papers.html (scroll though these papers for various methods of condensation control issues as well as achieving dry air in an energy efficient manner)

http://oikos.com/esb/53/hydroniccool.html

And do some Google searches on "radiant cooling humidity control" for more stuff.

jerry scharf_2

thanks

Geoff,

As usual, a great response and a bunch of information. So much more the learn. I will definitely keep an eye out for using this in future projects.

One nice advantage I see is that I can make the controls less costly by having them do double duty for hot and cold distribution. I had to do two parallel control systems for heat and A/C. Damper motors and dampers are both more expensive and less precise for me that proportional globe valves. Ventilation tends to be a more set and forget kind of thing.

Actually, 20 BTU/sqft seems like a large amount. That comes to 5 tons (boy we love antiquated units) for a 3000 sqft building. Well within modern building envelope design.

jerry

rb_6

Cooling - Heating Coefficients

Here's a useful table for you.

Caveat: the coefficients (radiant plus convective)are dynamic in that they are a function of the average unconditioned surfaces temperatures in the room and allowable radiant asymmetry.

You can download a free spreadsheet from our site which allows the user to manipulate the room environment parameters to see how the individual and combined coefficients are influenced.

http://www.healthyheating.com/home-heating-system-design.htm

Bob Gagnon plumbing and heating

Radiant Cooling

I have been cooling my house for 4 seasons with just well water. I first run the 56 degree water through a fan coil unit with a drip pan underneath, then the water goes through my radiant heating system. The coil removes a lot of moisture and lowers the dew point in my house so I have no condensation and no sign of mold after 4 years. Two years ago when it was 100 degrees my house stayed around 70 degrees. After the water goes through and cools my house it goes to a multi-zone sprinkler system, when its hot you need the most watering anyway. This system is MUCH more comfortable than air conditioning, its like comparing forced hot air to radiant heating. Bob Gagnon

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

GMcD

Bingo

Good envelope = low heating and cooling loads + humidity control and small ventilation requirement + total radiant comfort. All three legs of the stool.

Good job, Bob. Another proof of concept. Now, we need to get the general level of expertise from the building designer end right through to the radiant system installer up to snuff and see how effective BIG energy savings and little to no NET premium costs to the project can be achieved.

rb_6

Bingo again

Exactly.