Radiant Ceiling

[michael930]

I am looking to do a radiant ceiling in small room (14 X15) in my home. I done a little research on line and have a small understanding about it. I would like to know if I can use onix or must I use PEX (only read about PEX) with some type of plates.
How do I go about doing a heat loss for a ceiling with radiant works?
Any help would be great.

[Christopher]

Michael,

Honestly, I've never done a ceiling radiant job. They were used in the 60's and 70's, I believe, but were really not that great. The problem is that all the heat they produce just floats around at the ceiling, and needs some fan system to temporarily force the heat downward. At that point it's not really a radiant system, but closer to a forced air system.
As such, RadiantWorks doesn't have the ability to model a ceiling radiant system.

All that aside, if you go ahead with it, you can use either PEX+ or Onix. The installation is the same as a regular staple up system, just upside down.

[dave1963]

Christopher, I am considering a ceiling application as well, but your point that in practice the heat ends up floating around the ceiling has me wondering. If the system heats primarily through radiation, then I would have expected this to be as effective as a hydronic floor (even more so because the tops of beds and sofas would be warmed rather than the undersides). Not true?

[Watts Radiant]

Dave-

Chris is talking about a few different things. First, the 'floating around' refers to the heated air by the radiant system. If the air is heated close to the floor, it will naturally rise to the ceiling by convection. If the air is heated by the ceiling, it won't naturally flow "down" to the people, it'll just hang out in high places.

The radiant portion, as you noted, doesn't really care where it's positioned, it shoots out in all directions until it finds a mass to heat up, line-of-sight. Back in the olden days with ceiling radiant panels, the radiant energy spread down into the room, but when people had their legs under tables and things, they were cold because no radiant energy could directly hit them. When you have the floor heating instead, you're more likely to hit cold feet and legs, creating a more comfortable atmosphere.

Lastly, when you have ceiling panels, there is no conduction taking place, i.e. there is nothing in contact with the ceiling. When you have a floor that's heated, the people are in direct contact with the floor creating more heat transfer from the source to the person.

Ceiling panels will work in most cases, but the common practice now is to use floor heat given the comfort issues identified above.

Michael, is there a reason you selected ceiling instead of floor? Is it a construction constraint or ? We can pretty much design anything in house with a little leg work, however our RadiantWorks software is limited to floor heating.

-MDR