Sunnytop, what started out as my trying to offer a simple and humble .02 reply post, was challenged by the heat rises fallacy. The beauty of the forum is to educate some, learn some, and try to stay on topic while doing it. I wasn't trying to be condescending, but the "heat rises" myth really needs to be challenged since this concept can be important when applied out in the field (e.g. no air inlet, no hot air to rise), and I couldn't let that pass by without educating those who are convinced otherwise - its simply a law of thermodynamics - I didn't write it, I'm just repeating it against some resistance. Noone likes to be wrong and I'm sure Bud or Mr Vincent might think twice the next time they say heat rises-thats all. In my defense, I was simply trying to answer the crux of your question offering the suggestion that electric radiant is OK and indicated for install under tiles (wasn't that the question? or did I completely miss the point here? Am I wrong about this?). If so, I'm still not sure if the tile experts have yet to answer that question directly. Somehow, my using the word "investigate" was misinterpreted as go ahead, do it! The foil suggestion was nothing more than an afterthought, but somehow became the focus of Mr Vincent, rather than answering what I thought was whether or not electric radiant could be placed under tile without disrupting the tiles. My only reason for suggesting the possibility, right or wrong, was optimizing your radiant heat upwards rather than down into the slab. I learned something thru the forum, and not ashamed to admit my ignorance, because, after my 'investigating' it, the foil would conduct heat downward rather than reflect it upward, unless you had an air space above the foil insulation barrier (as in the case of a 'staple-up' job for a hydronic system). Applied science. I'm sorry if using science and trying to constructively argue some points sounds sarcastic as interpreted above, but really, my intentions were to help you, rather than provide fodder for experts to attack.

This product is for professional installation in a cement mortar bed under ceramic tile or laminate flooring. It is a "floor warming mat" and should not be confused with a heating system for colder climates. It is not a good idea to install this yourself and it is wise to install it as a complete system so that the warranty for the installation, mortar bed, flooring and the mat are all inclusive. Premier is apparently made for Costco by Watts Radiant a subsidiary of Watts Water Technologies in Springfield, Missouri (wattsradiant.com). The Costco website claims some kind of additional comfort benefit from an "ultra-low Electro Magnetic Field" that is generated from the wiring. I would stay away from any company that made ULF health claims. Here is a link that might be useful: website

it would be easy to maintain the position that those words were appropriate and sufficient. so, any arguing the opposite point of view might end up in a zero sum exercise. the thing brickeyee did was to make it more practical to the end user who has to run with the knowledge obtained. the mental model is slightly altered when one introduces the notion of heat source. ta da. hope you are open minded enough to let it be. -- one thing I wrote wrong in my first post was not saying the heat source could be above the tiles (or below); any heat applied to the tiles.

You've probably never been in a home with properly sized ductwork. Don't feel bad, it's estimated that as much as 3/4 of the heating and cooling systems in the US are oversized. 2 stage and modulating furnaces are better, but I've lived in a home with both, and both can be very comfortable and the single stage equipment doesn't make it feel more dry that I can tell. BUt you are correct, multistage cna reduce the sense of dryness you might get with a less than ideal system. THe RH of hot air is lower than cooler air, but cool air can make things feel drafty. That's why radiant heat is popular. You essentially have very, very low air velocities and much of the heat energy is indirect infrared heat which make you feel warmer, similar to direct sunlight. Keep in mind too, that unless you have an outdoor rest control for hte boiler or to sped up or slow the circulator, most hydronic air handlers are single stage for heating. So the heat is no different than a furnace. Worse, as you reduce BTU's to the coil, the airflow speed is usually ocnstant, so air temps get cooler. My point being, that a properly designed and installed furnace won;t make it feel dry even if single stage. But yes, oversized furnaces and those with restricted airflow can. Vairble capacity will always make the system more comfortable, but it will cost more. Radiant heat overall is superior, but the installed cost is much, much higher. That's why it fell out of favor. Same reason drywall took over the market and plaster disapeared. ITs' primarily a matter of cost. It's also why stone and brick homes aren't built anymore and concrete homes are the minority.