Hardware store radiant cooling

Keith_8

Something to think about.

So, you have 61* leaving the coil. I'm wondering how much warmer that could become and still be effective? Maybe slow the water down?

I think I would be inclined to send the water back down the well, we only water my lawn on average 2 times a year. Worth looking into. The well pump is less expensive to operate than my 2 condensing units.

Keith

Eric_25

Commercial radiant cooling

I have read over time various comments on The Wall about radiant cooling (I just searched the subject to refresh my memory) I haven't seen anything about it in a commercial application, has anyone tried it? We have a 20,000 sqft. hardware store with geothermal we are about to begin installing, it will have in-slab radiant heat and chilled water cooling via air handlers. Any thoughts about circulating the chilled water through the slab to assist the cooling? What about employee comfort from standing on a cool (65-70F) slab? I guess that wouldn't be any different than a winter slab if it did not have radiant. Any comments would be appreciated.

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hr

Actually the True Value

hardware store in Park City has a chiller on the radiant slab system. Low humidity in Utah allow it to work fairly well.

There was a point (temperature) where the gals sitting at desks would complain about the floors being too cold.

Did you try www.healthyheating.com. I believe RB, anf Geoff have some radiant cooling data in a thread over yonder.

hot rod

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GMcD

Commercial Radiant Cooling

Yes, there are many installations of commercial building radiant cooling - literally millions of Sq. Meters in Europe, Bangkok Airport, and many thousands of SF in the US and Canada now. They are a mix of radiant floors and ceilings. Most of the radiant cooling systems I design are radiant ceilings (heating/cooling), however there are many radiant floor cooling systems operating in the US right now as well.

Pier One in San Francisco is a big system installed in 2000-2001, Google the Davis Energy Group in California and see some of the projects on their website, and Uponor has some good case studies of thier product installs.

Mike T., Swampeast MO

It's all about relative humidity and dewpoint. You can't let water condense on the floor!

If you're in an area with typically low relative humidity, you shouldn't have a problem. If RH is typically too high you have to do something to lower it--and such might not be too easy when there are likely a number of doors open very frequently. If using a conventional A/C system to dehumidify it's possible that you'd have to turn the place into a virtual refrigerator to allow the slab to "assist" with the cooling.

Large mechanical dehumidification equipment is available, but since cooling is still part of the system if you use it only for dehumidification you're wasting the cooled air produced.

If humidity is low to begin with, evaporative (the so called "swamp" coolers) are extremely efficient as you're only running a fan. (They do of course require fresh water.) I haven't seen the numbers but the swamp coolers may very well be more efficient than the geo hydronic slab cooling.

I've heard of dessicant systems for removing humidity, but believe they're way too expensive for general use.

GMcD

Yes, but

Through the use of return air as the reheat for the cooled dehumidified air, one can achieve energy efficient de-humidification while doing radiant cooling. The Dewpoint, not the relative humidity, is the key design point. I agree that the more humid the summer climate, the more mechanical cooling for dehumidification will be required, to the point where the airside cooling is going to be there anyway as a default of the dehumidification process.

Radiant cooling is a climate specific system- and also includes a requirement for a very good building envelope- the worse your climate, the better your envelope has to be to use radiant cooling. Watch the solar gains at the windows especially, radiant floor cooling only has an effective "output" of about 12 btuh/SF due to the minimum comfort floor temperature of 65F-66F, and furniture/floor covering masking, while radiant ceilings can have an "output" of up to 25 btuh/SF with 62F surface temps, but then dewpoint control of the ambient air becomes that much more critical.

Eric_25

thank you

> Through the use of return air as the reheat for

> the cooled dehumidified air, one can achieve

> energy efficient de-humidification while doing

> radiant cooling. The Dewpoint, not the relative

> humidity, is the key design point. I agree that

> the more humid the summer climate, the more

> mechanical cooling for dehumidification will be

> required, to the point where the airside cooling

> is going to be there anyway as a default of the

> dehumidification process.

>

> Radiant cooling is a

> climate specific system- and also includes a

> requirement for a very good building envelope-

> the worse your climate, the better your envelope

> has to be to use radiant cooling. Watch the

> solar gains at the windows especially, radiant

> floor cooling only has an effective "output" of

> about 12 btuh/SF due to the minimum comfort floor

> temperature of 65F-66F, and furniture/floor

> covering masking, while radiant ceilings can have

> an "output" of up to 25 btuh/SF with 62F surface

> temps, but then dewpoint control of the ambient

> air becomes that much more critical.





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Eric_25

thank you

I have been reviewing the info at HH and the Wuponor (Upirsbo) website per yours and HR's sugestions. We are in NH where the outdoor RH gets fairly high from time to time but not usually for a long period of time. I am considering using variable speed A/H's with the chilled water to maximize the humidity removal in conjunction with maintaining the floor temps around 65F. What do you think of the operating cost benefit of doing the install this way as opposed to strictly using the Geo system with the A/H's to provide the cooling. We are in a heating dominent location so we will have roughly 10 tons of cooling capacity more than we will need. We could eliminate one or two A/H's (or reduce the size of one A/H) and reduce the associated ductwork by cooling this way.

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Mike T., Swampeast MO

Thank you Geoff.

The Swampeast MO climate probably makes me overly cautious and I might even appear pessimistic with regards to radiant cooling.

I understand that it's dewpoint that's the key point for providing the radiant cooling, but relative humidity still enters into the equation. Go much above 60% relative humidity what I consider a reasonable temp for A/C (say 78F) will feel "stuffy" and you'll want to take the temp down further which only increases the RH unless you have some way to remove it. At 72F or so and 80% or so RH you'll experience the "dankness" of caves and mold/mildew will flourish...

The "dank" feeling as well as the mold/mildew problems are the very reason why so many people in my area run dehumidifiers in their basement--even if it has mechanical air conditioning.

As you might guess, radiant cooling is essentially out of the question in the mid-Mississippi valley. The only thing I can seem making it practical is a dessicant-based system using "waste" heat from the air cooling process to dry out the dessicant when needed. Tall order, but supposedly doable. I Wallie from Iowa who I correspond with is trying to do something very similar.

S Ebels

Bangkok?

You mean the Bangkok where the RH is like 98% year around? How do they prevent condensation with that much moisture in the air?

Brad White

Confucius Say... Man who get on airplane sideways...

going to Bangkok

The key to radiant cooling is keeping the surface temperature above the dewpoint of the space. Limiting use of outside air to the minimium (no need for economizer in those climates), they actually use face and bypass dampers to sub-cool much of the air and bypass the return around it (as Geoff noted in another post). Using the bypassed air as reheat essentially.

Also the use of brines to produce very cold air (40 degree saturated) as a dehumidification agent, works wonders.

Beyond that, the chilled water used in chilled beams and other radiant cooling surfaces is mixed much as you do for radiant heat, to raise the temperature above the dewpoint but still be below the space temperature. This is why though, it takes a LOT of surface area- the delta-T's are very narrow.

Radiant cooling is a 'sensible' thing to do. :P

Bob Gagnon plumbing and heating

Radiant Cooling at my house

Works great, I send 56 degree well water first through my fan coil unit which removes the hunidity and cools the air. the water then flows through my radiant panels, keeping the floors a cool 68 degrees. The cool floors are very comfortable in the hot weather, cool radiant comfort, your house is cool to the core! Thanks, Bob Gagnon

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GMcD

Read this

Here's a link to a short summary on the system at Bangkok Airport:

http://www.transsolar.com/download/e/TRANSSOLAR Concept for the NBIA.pdf

GMcD

Nice

That basic system is easily applicable to any large scale commercial system. A Total Comfort System in action.

I assume you've also read how the Cool House is doing in Deep Creek - www.ourcoolhouse.com

NRG Systems in Vermont uses a radiant floor cooling system in their building - see this link:

http://www.nrgsystems.com/about/green_building.php?tid=212

Bob Gagnon plumbing and heating

thanks

I like to keep it simple and reliable. The only thing I would like to add is a dewpoint sensor in the floor to shut off the floor pump if the dewpoint is too high. But so far I have had no problems with moisture or mold. Bob Gagnon

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Keith_8

Bob,
Do you dump the water back down into your well when the sprinklers aren't required?

What controls the well pump? Is it operating off of the pressure switch or a temperature sensor on the primary loop?

What is the delta T on the fan coil unit?

Any issues with the premature well pump failure?

Looks interesting.

Keith

Bob Gagnon plumbing and heating

no dumping

I have a point driven well so the water is unlimited. If I don't need it I let my neighbors use it. The water is very expensive here. I did another radiant cooling job for a customer and he had a deep well so he sends some of the water back down the well. When the thermostat is in the cooling mode it opens up a solenoid valve to the sprinklers, and the pump pressure switch takes over from there. The delta tee is a little low, I think it is about 5 degrees with the fan coil and radiant panels. The well pump has lasted. I bought a used one in 2000 and it is still working. As far as I'm concerned radiant cooling is a done deal. It has worked great at my house for 6 seasons now, with no problems. Solar heating will take more work though. Thanks, Bob Gagnon

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Peter Groenewold

Looking good

Hey Bob,
Nice design. I am rebuilding my house in PA this summer and I want to do some similar things. I will have ICF walls, 30% of the lowest floor underground, Radiant heat, and a horizontal geothermal loop.

I am very interested in using this system for cooling as well. One thing we have going for us is that my wife and I don't like it real cool anyway. The old house never got real cool either.

You mention radiant panels. Does that mean you don't have radiant floors?

I don't see a heat pump. Are you not using the geothermal loop with a heat pump for your heating?

Thanks
Paul
A Real Good Plumber, Inc.
917-939-0593

Bob Gagnon plumbing and heating

no geothermal loop

I pump the water directly from a point driven well, and I have no heat pump. You should be able to cool that house easy, I have 2X4 walls, standard fiberglass insulation, and staple up for floor heating/cooling. The radiant panels are my walls and ceilings. At 70 degrees my house is too cold for some people. Bob Gagnon

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