Hydronic heat, insullation and radiant b
GOLDENBOY
| Posted in Energy, Heating & Insulation on
Hi, I’ve been asked to finish a basement. The upstairs and basement have hydronic heat, with upstairs tubing clipped to subfloor with diffuser plates. The owner says the plumber who installed the heat suggested insullation and a radiant barrier under the tubing, with an airspace between radiant barrier and tubing.
Joists are wood I’s 19 3/16 o.c. What level of insullation is desireable?
Also what sort of material is used for the radiant barrier?
Thanks.
Replies
I put that in my house. The tubes are above the subfloor laid in gypcrete. Under the subfloor foil,bubble,bubble,foil sandwich which you can get from Tec Supply. Insulation is useless unless you have a very cold basement, as heat rises and stays above the foil/bubble barrier.
Stef
Huh??????
Hot air rises. Heat travels in all directions. Any differential in temps and heat travels from hotter to colder.
Try standing under a radiant tube heater.
You beat me to it. I can't belive how often I hear "heat rises" from people in the trades. Most of whom should know better.
Thats why the foil, bubble, bubble, foil.
The foil reflects the heat up from the tubes, and the bubbles and lower layer of foil prevent the lower heat levels below from creating that 'Delta T' you are referring to.
Stef
"Hot air rises. Heat travels in all directions. Any differential in temps and heat travels from hotter to colder. "
Initially but hot air is lighter than cold so makes it way above comfort area. This is what makes radiant heat so effective, it puts heat in areas where we poeple want it longer than a radiator would.
Jeez,
No one answers your question.
With that spacing, consider foam board with foil face pointed up.
1 or 1.5 inch is ok. Gun foam around edges to seal.
You only want enough space so that the foam is not touching the tubing (or plates).
Or you can staple up insul tarp (or similar). The insul tarp generally goes up faster.
In my experience I'd skip the foil and just use unfaced fiberglass batts 3-1/2". That's going to be all the insulation you're going to need over a heated space. If you spend the extra money and install the foil, go back in about 5 years and see the layer of dust on it. As soon as you loose that nice shiny surface, you loose your radiant reflectivity. You should also allow a 2"-3" air space between the insulation and the tubes/ plates. this allows the temps to equalize across the floor and prevents heat striping. the only times you want to go up tight against the floor is when the radiant heat delivery is on top of the floor IE: gypcrete, Warmboard, etc.
For more info check out http://radnet.groupee.net/eve/ubb.x/a/cfrm/f/2771065301 and search insulation. This is the forum area of the Radiant Panel Association. Lots of good info there!
Hope this helps, Rich