In floor radiant heating

[jimialeggio5 at comcast.net]

Cy

There are different radiant heat systems, but the 
key is they heat by the same wave form mechanism. 
 
The sun is a radiant heat source. You stand in the sun
and feel warmer irrespective of the ambiant temperature. 

In all these radiant systems, whether it is radiant panels on
the walls or cielings or floors, the heat mechanism is wave forms
heating the objects first which then heat the air by conduction.  The heat 
does not progress from the floor and then rise to ceiling except secondarily
as the warm objects themselves heat the air by conduction. Thus convection in
radiantly heated homes is seriously reduced, which leads to the comfort factor
associated with radiant systems.

Forced hot air, baseboard heat, etc heat the air which then heats the 
objects by conduction.  ie much convection, much air movement.

Since the radiant systems heat objects (including people's personal
objectified bodies) the temp of the building is often comfortable at a 
lower themostat setting....assuming not too leaky a building.  

If the radiant heat is installed in a leaky building, the radiant surfaces 
will need to be warmer than in a less leaky building.  In addition,with 
greater amount of dry (absolute Humidity) air coursing through the
building because of the leaky nature of the building, the RH will drop...
this is where the moisture EMC problem with pianos, furniture and people's 
sinus's occurs...not necessarily the heat source.

Jim I