I have been to a few shows, a seminar and read this forum extensively. I like a warm home. My family has a few older folks that seem to have no blood and run their heat at about 80 degrees. Sometimes when you come home you want to get off the wet clothes and really crank up the heat for a little while.
I have a sip home under constuction and allowed an extra 1/2" for a radiant floor "dry" system on a layer on top of the sub floor. While a radiant floor I expect is great for achieving a nice ambient temperature I have the impression a house that is kept nearer to the 78-80 degree area is not suitable to it.
I don't know. I havn't been in a radiantly heated home yet. How do I practically address this?

Thanks

A properly installed and operating radiant floor should easily be able to generate the heat, especially in a SIP home. The only adjustment that I could think of would be a tighter pipe spacing. I'm sure that NRT Rob will also give you an opinion.

no one runs a radiant system at a true 80 degrees. You'd probably die. Ok, that's exagerrating, you can get used to anything, but typically anything over 72 to 74 starts getting pretty stuff when you are actually successful at raising your home's mean radiant temperature.

It also starts getting really hard to meet heat loads at those room temps. Not only do the heat loads rise, but you can only raise the temperature of the floor so high (about 90 for tile, 85 for wood). approximate radiant output is 2 BTUs/sq ft per degree above room temp that the average floor surface is. So if your room is 80, you can only get 10 to 20 BTUs/sq ft out of radiant floor before you "endanger" the wood or make the floor too hot to walk on. that's adequate only for well built homes.

I am new to this Green Talk Forum and I missed this thread from/since last year. Let’s see if I can contribute my 2 cents worth.

This is almost the same posting I just did in other thread in this web site. Sorry for the repetition.

I am very familiar with the BEKA USA capillary tubes for radiant heating AND cooling in the same installation. Just switch the tap water temperature from warm to cold and you go from radiant heating to radiant cooling. I you want to cool the water further below freezing (with glycol) you can get a freezer (a Penguin’s cage in the Berlin Zoo –Germany –) and in between if you want a wine cellar (at 56-58°F year round) or any other temperature for medical, commercial, industrial goals, etc.

The system and the techniques are the same and any installer that familiarizes him/herself with the system now has few new lines of business opened at once. The system is extremely easy and safe to install and very fast that saves you labor big time. If the installation is small, yes it may be a little bit more expensive but this is the “Cadillac” and 21 century HVAC system. You should pay more for comfort and a healthier system. As soon as you are in 2-3000 ft2 or more the total system may not cost you more than other systems. If you go to an even bigger installation the system may not only be “for free” but may leave up to 15% savings in construction upfront moneys. The system installed as BEKA USA recommends, welded to itself all by fusion, running water between 60 and 95°F, should last over 100 years. There is no possibility of condensation because of the BEKA USA system. If you get condensation it will be for some other reason. It comes with a fool proof shut off as you are even close to reaching the dew point, whatever it may be at that moment. You can have diferent temperatures at the same time in diferent rooms as per each dweller's desires and comfort level. You will need only 1/4" of ceiling space.

Some comments said that it may be a little expensive ($4 for the mats and $4 for plastering – although you do not “have” to plaster) you have to add the piping to take the water from/to the control panel and the control panel itself. The BEKA USA mats come with a 15 year warrantee and BEKA has over 20 million ft2 installed worldwide.

BTW the BEKA USA system is installed in the ceiling and very rarely and only in extreme or special situations, in the floor, like if you only want a radiant heating installation.

check out -->> www.bekausa.com

Vinmeister, Worked in an office bldg in Germany with radiant floor heating and experienced very warm floors and an ambient temp well over 80 degrees. The system was capable of producing plenty of heat, but there is a point where the floor is very uncomfortable as NRT.Rob stated. Your feet sweat, you sweat and you keep sweating until the floor temp slowly goes down after you adjusted each loop's valve. That's right..no thermostat for control. A modern control system will keep temps more even, but I think you might be disappointed with too high a floor temp.

I lived in a house with radiant heating for 25 years in Long Island, New York. When I bought the house I didn’t know anything about radiant heating. I was told that is was great! Yes, it was until it got hotter and hotter. It was unbearable. So, we lower the boiler’s aqua stat water temperature set up during those “indian summers” but few days later it got colder again and the water temperature now coming from the boiler was too low to take care of the needed heating. The solution was to manually change the water temperature to match the outdoor temperature and then wait until the next day for the floor to reach the target temperature. Not good as you can imagine.

Serendipity brought the solution. Just at that time there was an “oil crisis” and in order to save heating fuel some “entrepreneurs” brought to the market a little “computer” for about $150 at that time (+-1978?). It had an outdoor temperature sensor in one end and another indoor temperature sensor at the other end. The “computer” got a potentiometer were you regulated the sensors temperature differential and the indoor sensor was tightly taped to the copper water pipe coming out of the boiler and going to the hydronic system of which the radiant tubes (copper) were just another circuit of the hydronic installation. No multiple valves there, just 2 circuits (2 circulators from the boiler controlled from 2 thermostats) one feeding the radiant floor and the other to the hydronic radiators.

Like all boilers it had the firing box to keep the fuel pump bringing and vaporizing fuel and the sparking for the burning flame to keep burning. If the fuel stops or if the flame went out for whatever reason, the boiler stops functioning and you don’t have a fuel spill or a big house fire to happen. But that box also has “interrupt” terminals. If you join them, the boiler stops. The boiler’s aqua stat may be calling for burning fuel to keep up with the boiler’s set temperature but the “interrupter”, activated from this “computer” acted as a jumper and interrupted the burning boiler from achieving the set boiler’s water temperature. Therefore the “real” aqua stat set up was decided by this little “computer” interfering with the normal aqua stat set up.

If the outdoor temperature was going up, the boiler was interrupted earlier and earlier and the boiler’s water circulation although was not interrupted but it was running less and less hot water to the whole hydronic system as determined by the outdoor temperature without any human intervention. Of course, when the outside temperature went down, then the boiler water temperature went higher and higher as needed. The aqua stat initial set up was not interrupted or tinker with.

For over 20 years then on I was amazed that all the Home Heating Oil Company’s service technicians (check up and calibration included “free” if you had a yearly fuel contract), none of them understood what they were looking at. I had to explain again and again to any and all the new technicians that came to boiler service. I was the only one from all the thousand of clients to have such “smart” set up. Now I live in Phoenix, Arizona.

We set up the room thermostat at a comfortable level and the boiler’s water temperature was automatically adjusted to the outdoor temperature and in relation to the house envelope’s performance. All without anybody’s intervention. It became really a very good and comfortable not only radiant floor heating system but the rest of the hydronic system was also better and smother, running water at the right temperature in relation to the outdoor temperature to the rest of the hydronic radiators.

That is when I learned that radiant heating floor is only good if it is automatically regulated to the current outdoor temperature and the “envelope’s” performance.

That little box was marketed because at that time (1978?) heating fuel was going to go up to $4gal and it was going to save you big money burning only the needed fuel. It did save fuel (at $0.90 then) but the major major impact was human comfort from radiant floor heating. It took about 30 years for the fuel to reach that “expected” 78's money level so maybe these boxes are now available all over the place. See if you can find one and install it. Your life, and your family’s life, will change for the better.

Now you have radiant cooling and heating in the same installation. See www.bekausa.com

You can't be more comfortable than it a properly designed radiant floor heated home.