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Radiant countertops

Posted by mudflap (My Page) on
Mon, Mar 4, 13 at 1:15

I am wondering if anyone has any thoughts on this crazy idea. I will be building all the cabinetry in our new house. I am also planning on putting in concrete countertops.

What if I ran our radiant heating thru the concrete countertops? The countertop would have to be thicker to allow for the tubing, but why not turn this gigantic piece of cement radiate heat. I can only imagine how toasty the kitchen would feel

I think this is an excellent idea. Imagine this in the bathroom.

As another thought, I plan on running cold water thru the system during the summer. The water coming from the well will run thru the house, then to a solar radiant transfer tank then to the hot water heater.


Follow-Up Postings:

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RE: Radiant countertops

You don't cook do you? Just imagine how quickly butter will melt and how spills will become dried to the surface. How there is no place to roll out pasty dough. And in the summer how much condensation will appear on the floors from their dewpoint being so low. Ever have an iced beverage and a water ring?

Others have already had these schemes before. And there are reasons they haven't been implemented. Take a basic science course or two. Learn some real world HVAC applications. Learn about geothermal.


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RE: Radiant countertops

Hot water radiant heat in concrete slabs work because of the large surface area available. Using it in a counter would be ineffective. Such an installation would heat the cabinet space below unless insulation was installed under the counter. It seems like a lot of money and effort for an odd novelty but so are concrete counters.


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RE: Radiant countertops

Thank your for all of your wonderful feedback.

Holly, Thank you so much for bring up science. I had completely forgot about the basic rules that rule the universe. My masters degree in horticulture had no science courses in it. I had not even considered that the water I would be bring up from the "earth" via my 200 foot water well would be ice cold. I had completely forgot how cold or hot water is when it comes out of the "earth".

I have also cooked my entire life and am considered by some to be a decent cook. I am glad you brought up the melting of butter. Butter melts around 90 degrees F. I will be sure to keep my room temperature below that to avoid burning my butter to the countertop. We usually keep the temperature around 64 degrees F.

I will also be on the lookout for other "outside of the box" schemes.


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RE: Radiant countertops

Not so crazy as some may suggest. Do an internet search for 'radiant heat kitchen counter tops' with a good search engine. Tom Silva of TOH has them and says they are great for making bread on. But I agree that cooling through concrete is impractical.


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RE: Radiant countertops

I like "outside of the box" thinkers!


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RE: Radiant countertops

Tom Silva's counters are granite instead of poured concrete.


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RE: Radiant countertops

To use any hyronic as a heat source, the loops have to be warmer than ambient temperature so that you get the heat to radiate into the room. That means typically 110 degree water through them. Some systems that depend on faster circulation through heavier pumps can run lower water temperatures, like 80-90 degrees so that wood or other not efficient floor coverings can be used. Those aren't as efficient, and have greater maintenance expenditure for pumps as the years go on. The average 60 square feet of counter space that is in a kitchen wouldn't provide nearly enough surface to volume ratio area to efficiently heat the room without some sort of supplemental heat. In addition, the work surface itself would be uncomfortably warm if you did manage to use water hot enough to heat the room with.

Now, if you were talking about the electric cables that people have used to warm their bathroom floors with, that's another story. It still won't heat your room. It will just take the chill off the counters by heating them slightly above ambient temperature. Say 80 degrees instead of 68. The only reason stone counters seem "cold" to you is that they are a large thermal mass that conducts heat quickly away from your body parts that touch it. The counters aren't any colder than the air in the home is. You just perceive them as cold because of the mass quickly removing the heat from your hands. Heating them to keep the perception of cold away isn't at all functional. It's a several hundred dollar luxury that some people feel is worth it to them, Tom Silva included.

BTW, concrete may be low cost if you DIY, (ONLY DIY, if you have a pro do it, you are above the cost of even expensive granite) but it is as porous and etches like any marble counter . Sealing only helps to prevent stains. It doesn't prevent etching at all. Unless you encase it in a plastic like sealer. At which point, why not just get plastic to begin with?

As far as cool water in the summer creating condensation, yes, that's correct. It doesn't have to be ice cold. Just lower than the dew point with no humidity removal system addressing the ambient humidity like traditional AC does. If you run 60 degree water through a system in the summer when the ambient dew point is 82 degrees, you WILL get condensation on the floor. It's why your garage floor "sweats" in spring when there is a rapid temperature shift from cold to warm. The cold mass hasn't had the chance to warm up, and when it contacts the warmer air, dew results. It's not very pleasant or safe when that occurs inside your home.

There is a HVAC forum on here that it would be well worth your time to read the past threads in. It's one of the largest expenses on any home, and yet many people don't even understand the basic theory behind why it works or doesn't.


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RE: Radiant countertops

Nothing wrong with out the box thinking.

not all building decisions are practical.
some are based on the quirks of the homeowner
or builder.

if we did only practical things in building homes,
then there would be only ICAT recessed lights
and all ductwork would be in living space.

ditto on hvac. put a lot of thought to what will
provide the comfort of your everyday life
in your home.

best of luck.


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RE: Radiant countertops

When we were remodeling our master bathroom I made endless trips to our local tile shop. Their front counter was topped with a granite slab, heated with one of their electric mat systems that they sold for heating tile floors. It felt so good to lean my arms on that counter! I could imagine if you had a kitchen island where kids like to do homework that it would be wonderful to work on a nice, gently warm surface.


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RE: Radiant countertops

We're planning a hydronic heating and cooling system ... but in an area where the dew point will be below the temperature of the floors when the cool water is flowing.

Humans perceive the rate of heat transfer from the body rather than temperature itself. You don't get a "toasty warm" feeling with thermal mass heating because it's not radiating at above body temperature. It's warm enough that your body doesn't sense it as a "heat sucking surface", which leads to feeling comfortable.


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RE: Radiant countertops

This is a topic that occasionally gets very heated (ba dum dum) over in the Kitchens forum. For some reason not quite clear to me, professional kitchen designers appear to be exceedingly negative about any innovation that isn't completely mainstream. Or maybe it's just the cranky ones who post online. ;-)

Living in the cold far northeast, I applaud heated counters. Those who don't live in the cold often forget the basics of heating buildings, such as setting back the thermostat at night/during the workday, and how slowly mass warms up relative to air/body temperature. I had unheated granite in an old house here in Maine, and absolutely couldn't stand it -- I got heartily sick of my coffee going cold wicked fast if I set it down on the counter.

Here are some threads from the Kitchens forum, for your reading pleasure, hopefully containing more helpful input than gratuitous snark:

Heated Countertops?

Heated Granite Countertops

One member describes how much she adores her heated granite island (you might want to search her posts, I believe it was a DIY project; even though you're looking into concrete, she may have good input for you from her experience?):
DIY island


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RE: Radiant countertops

You reminded me of a very fancy restaurant I was in many years back where we had a business meeting so the meeting was held in the wine cellar which of course is kept cool, so they heated the enormous granite table around which we were all sitting, so we were fairly comfortable and so was the wine....

Here is a link that might be useful: Wine cellar


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RE: Radiant countertops

I'm not cranky. :*) Well, OK, maybe a little bit. While heating your kitchen counters can be done, and if that project is what someone wants to float their boat, then whatever. What cannot be done is to use them as a radiator to heat the room if they are also going to be used as kitchen counters. Anyone ever have old fashioned radiators in their home? Do you want to make a sandwich on top of that? Maybe if it's a grilled cheese you would, but otherwise it wouldn't be such a good idea.

I have heated bathroom floors, and the house had radiant heated ceilings as well. The thing that most people don't understand about radiant heat is that it depends on a large thermal mass to radiate that heat. And, that large thermal mass has a pretty big lag time from adjusting the thermostat. If we wanted to turn up the ceiling heat, it took an hour or more to feel the results. And then, we usually felt too warm. It's VERY comfortable. But it's not forced air where you can tweak a degree or two in 15 minutes time. For the bathrooms, which are only what remain in the home now, if you get a warm spring day outside (like yesterday), the warm floors are providing too much heat for the room, and you have to open the windows. They won't cool down fast enough to not have you be HOT if you have a rapid warmup. That is how all radiant heat works. It'sresponse time isn't very suitable to a climate with rapid daily temperature swings. It's more suited to a cold environment climate that gets cold and stays cold.


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RE: Radiant countertops

I think that if you heat your counter tops to a temperature that makes them feel warm, the result is that they will seem to be made of a less thermally conductive material, like plastic (or Corian). Just using corian or a similar solid surface might be a simpler and less expensive way to get the same effect.

Instead of heating the counters, I wonder if you could put in a stone wall and heat that? Then you could use higher temperatures than you might want to use in a counter top.


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RE: Radiant countertops

" It will just take the chill off the counters by heating them slightly above ambient temperature."

Stone, concrete, or tile counter ARE already at room temperature.

they FEEL cold to the touch because we are 98.6F (a little cooler in extremities), and counter shave avery high mass and rather good heat conduction.

When you touch the wood table it is at room temp also.
But wood is not as massive or as god a heat conductor, and has a low specific heat, so your body heats up the spot you are touching easily and it dos not feel cool for more than a very short instant (unless it is VERY cold).

Not so with stone or tile, or concrete).

Every material has a 'specific heat.'
The amount of heat required to raise a standard mass of the material by a specified temperature.

Stone has a VERY high specific heat, and conducts very well also.


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RE: Radiant countertops

I agree with zone4newby if you're going for a warm feeling. The other thought I had was a dark counter top by a sunny window sure feels nice in the winter. If the counter is near a South window that might help.


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