Under Floor Radiant Heat - A Historic & Modern Overview

Since Roman times, radiant heating techniques have kept people warm through comfortable, convection type heating methods. The premise is simple and clean: heat energy emitted by a radiant source warms people directly rather than warming the air around them. Since air can flow from room to room, and we know heated air always rises, radiant heat is the ideal way to keep the heat where it's desired most - at floor level.

Radiant Heat - First Used by the Romans!

Since the Romans first used hot air and brick lined furnaces beneath the floors of their bathouses to keep warm, radiant heat technology has received some major upgrades. Heated water is now used instead of heating ceramic or stone, and the flexible tubing the water passes through is laid out in such a configuration as to maximize heat convection over the entire floor space. This allows for a much larger heating surface, with the circular design of the tubing allowing for exposure on all sides. Because of this, a much lower water temperature is required to achieve the desired levels of convectional heat transfer. This is why modern radiant heat is often called a low-temperature system, which contributes greatly to its overall energy efficiency.

Energy Saving Tips - Radiant Heat A radiant heat system saves an average of 10-15% of your energy bill, paying for itself in total energy savings over the course of 5 to 7 years!

Effectiveness of Radiant Heating Systems. . . And How They Work

The most efficient part of a radiant heat system comes in the form of comfort. When the feet are warm, a person feels warm all over. Since radiant heat warms you from the ground up, people find themselves a lot more comfortable at temperatures that are lower than normal on the household thermostat. This translates to straight-out energy savings in heating costs simply because your furnace or boiler will be running a lot less of the time.

Heat from a radiant system stays lower in the home, too. While hot air from a blower or forced-air type system will rise, convective heat produced from the floor warms you and not the air. Therefore temperatures near the floor will always be warm, with cooler air toward the ceiling - the exact opposite results of conventional type heating methods.

A final benefit of radiant heating would be the visual aspect - no radiators, blowers, or return vents to worry about. This allows homeowners to place furniture a lot more freely, without having to concern themselve about covering an air conditioning or heating vent.


Modern Options in Electric or Hydronic Radiant Heat Systems

These days radiant heating systems can be broken down into two options: electric or hot water. Both have their own advantages and disadvantages, yet both are effective methods of heating a home or building through convective means.

Electric Radiant Heating

Electric Radiant Heat

This involves the installation of a heated cables throughout the floor of the room to be heated. A much smaller diameter is necessary than that of radiant water systems, which can lessen the required floor height. Also, electric radiant cables are usually designed with a built-in return. This means they can be laid out in any desired pattern without having to worry about completion of the circuit, as in water-based radiant heating. Pre-made radiant cable mats are now available, already perfectly spaced over nylon mesh. These can be rolled out over the desired floor space, speeding up and neatening the installation process overall. Electric radiant heat is very popular in bathrooms and kitchens, because it's rather simple to install under ceramic tile.

Hot Water Radiant Heating

Hot Water Radiant Heat

These systems circulate warm water through plastic or PEX tubes laid into the flooring of a room or home. Because any type of gas, oil, or fuel furnace can be used to heat this water, it offers a pretty flexible alternative to electric radiant heating. The overall energy efficiency of water-based versus electric systems is greater, and performance is generally better. Laying out the tubing can be more difficult however, because ultimately both ends of the circuit must be attached for circulation to function. This needs to be taken into consideration when designing the layout for any hot water radiant heat system.

In both types of heating systems, the quality of materials must be carefully considered because an under-floor repair would be difficult and costly. Water systems, although efficient, add another layer of equipment (the pump and/or circulator) that needs to be taken care of. Electric radiant systems will have a faster install and generally require less maintenance. They can also be controlled more easily at the electronic level to run the system when needed.

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