Radiant heat better than baseboard?

[Doug Miller]

With respect to conduction, yes...

Tell you what: you drop trou, then sit on an 80 deg F block of steel, and tell us if it feels warm. Stay there a while.

This may come as a surprise to you, but if a 98.6-degree human sits on an

80-degree block of steel, the direction of heat transfer is *from* the human, *to* the steel. Not the other way around. After thirty minutes bareassed on that block of steel, you're going to be shivering.

Nonsense. Forced air heat isn't "stifling" hot.

Uh-huh. Right. I guess you mean 30 deg *C* here.

Different strokes...

You have an *odd* definition of "warm".

Well, that's the source of your trouble - you shoulda used an air conditioner.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

[fredfighter]

It is also true for Newton's law of cooling which governs conventive heat transfer. Radiant floor heating heats your feet by conduction and the air in the room by convection. Radiative heat transfer is negligible, the descriptor 'radiant' is a misnomer, similar to the 'radiator' in a car.

...

bareassed on

Agreed but with the caveat that 98.6 is the normal temp for under your tongue. I dunno what the normal temperature is for your butt cheeks.

The first two examples heat by convection. Radiative heat tranfer is negligible in a convective environment for such small temperature differences. Even though readiative heat transfer is proportionate the difference in the Fourth Power of th eabsolute temperature, the coefficient is typicall very small compared to the convective heat transfer coefficient so that free convection dominates unless in a weightless environment (but still dominates if there is a fan), or a vaccuum.

I don't think so.

[nicksanspam]

Conventive? :-)

Not much, compared to the rest of your body.

Wrong.

A 90 F body in a 70 F room might lose 30 Btu/h-F-ft^2 by convection and

0.1714x10^-8((90+460)^4-(70+460)^4) = 22 Btu/h-F-ft^2 by radiation.

Nick

[RB]

I think it's wise that when it comes to calculating convective heat transfer in radiant heated spaces that the conditioned panel orientation should be considered...ie: wall, ceiling or floor and whether the panel is in the heating or cooling mode and also what % of the surface is mechanical conditioned. The other calculation which influences the convective component is the MRT vis a vis AUST.

Here's a link to a spreadsheet which considers most of these factors.