This suggested criterion is based on the fact that the distribution piping and heat emitters in a well planned.
In floor heating water temperature.
According to ashrae the american society of heating refrigerating and air conditioning engineers a floor temperature that creates optimal human comfort for most people lies just about at 75 f as shown in this graph.
Building systems and materials.
Heating systems so that they can provide design load heat output using a supply water temperature no higher than 120ºf.
Heat losses to below grade.
All water heaters waste heat energy even when the burner is off and the unit is sitting idle between heat ing cycles.
To prevent this air humidity is kept low below 50 and floor temperatures are maintained above the dew point 19 c 66f.
Some types of heat emitters are best suited for relatively high temperature heat sources.
With underfloor cooling condensation may collect on the surface of the floor.
Granted the unit dedicated to heat ing the floor only wastes heat during the winter months.
For example the familiar finned tube baseboard convectors used in many residential and light commercial buildings work well with water temperatures above 150 f but not with low temperature systems such as ground source heat pumps see table matching the components.
Traditional radiators need to be heated to a high temperature between 149 167 degrees fahrenheit 65 75 degrees celsius in order to heat up a room effectively whereas floor heating only needs to run at a temperature of 84 degrees fahrenheit 29 degrees celsius or less depending on the floor finish in order to warm the room thereby consuming less energy and keeping your energy bills far lower.
When floors are conditioned within this range most people wearing normal footwear will enjoy having their feet on the floor.
But standby losses for six months out of every year can add up.
Even lower supply water temperatures should be used when possible.
Typical radiant floor systems operate at 85 125 f water temperature entering the tubing and put the floor surface temperature about 5 degrees above the room thermostat set temperature.
The down side is two heat sources.
As warm water circulates through the tubing or as electricity warms the heating elements the concrete flooring turns into an efficient inconspicuous radiator.