Radiant Underfloor Heating in History
Radiant Underfloor Heating is one of the oldest forms of heating in the world, dating back to Roman times. Common in public bathouses, or thermae, the Romans had invented a system in which hot air was pumped through chambers underneath their stone floors. The hot air would warm the stone and create a comfortable surface to walk on, as well as uniformly heating the entire bath house.
By the 12th century, Muslim engineers in Syria had developed an improved version of this technology. The new system involved a series of pipes running under the floors, which would transport hot water from the furnace throughout the house.
The concepts behind radiant heating haven't changed greatly in the past thousand years. While lead pipes were eventually replaced by engineered plastics, and boiler technology has improved significantly, radiant underfloor heating has always remained an attractive and beneficial alternative to forced-air heating systems. Today radiant underfloor heating is growing in popularity, due to it's increased efficiency, decreased operating costs (by up to 50%), and dependability. An underfloor hot-water radiant system is virtually maintenance free, and the piping used can have a lifespan of up to a hundred years.
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Radiant floor heating provides even, comfortable, warmth as there is less air movement with this type of system. There are no drafts with this type of heating, unless it is through the building envelope. The thermal mass (concrete floor) evens out the temperature fluctuations. The floor is warm to the touch.
Many manufacturers claim that radiant floor heating is more economical to operate because the temperature setting may be set to 20ºC (68ºF) rather than the usual 21-22ºC (70-72ºF) as required by other types of systems. A study by CMHC (Thermostat Settings in Houses with In-Floor Heating, #01-106) has shown that people tend to keep their thermostats set the same as if they had a forced air system. Even so, the warmest air is at the floor where it is desired (and not at the ceiling) and there is reduced heat loss through the ceiling and walls.
Zoning a variety of rooms with the options for different temperatures has the potential to reduce energy consumption.
Energy Source Compatibility
Since radiant floor heating has a low operating temperature, a wide range of sources can be used to heat the water: a ground-source heat pump, a condensing or non-condensing boiler, solar or even district heating.
The system is quiet because a properly-sized circulator pump, used to slowly move the water, is almost inaudible. The loudest sound in the system is usually the gas or oil burner.
Unlike conventional forced-air furnaces, radiant floor heating has no ducts or radiators to contribute to dust collection or movement. Note: duct work is required for the mechanical ventilation system or air conditioning.
For residents with allergies, the reduction in dust movement may be beneficial.
Hydronic radiant floor heating is virtually an invisible system. Without baseboard heaters, forced air registers etc, furniture layout is not restricted by the heating system. Bathrooms or special use areas with hard floor finishes are well suited to this type of heating.
Cautions and Solutions
Due to thermal mass, the system may be slower to respond to temperature changes. Overheating can occur in poorly controlled or zoned systems. The system is not designed to have the temperature frequently adjusted.
Night setbacks are not practical in most situations as the system is slow to react.
Ventilation must be done separately. As air conditioning cannot be used in ventilation-sized ducts, window/wall air conditioning can be installed or room-by-room split systems can be used. Additionally, high-velocity air conditioning systems that use small outlets in ceiling or walls have proven very compatible with radiant floor heating operation.
Extra support may be needed for the weight of thermal mass topping on a wood floor. If the building structure can't support the weight, then the dry plate system can be considered.
This is not a do-it-yourself project. It requires professional installation, maintenance and repair. Having professionals do the installation will allow you to have the best performance and warranty on the heating system.