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Radiant Heating Systems

A Description of Several Types of Radiant Systems
Including Our Preferred System.

Radiantec - Thinking outside the box

There are many ways to take advantage of the benefits of radiant heating and cooling. Some heating system concepts are at least 100 years old. Other systems are newer and more innovative. We urge you to at least take a look at these modern systems. The newer and more innovative systems can offer significant advantages. .

Please note that Radiantec often recommends the use of domestic water heaters instead of expensive boilers. Click here for more information about that use. This is an opportunity to save thousands of dollars and still have a better and more energy efficient radiant heating system.


(both heat and domestic hot water are provided directly from the same heating unit)

Legend for Open Direct System Heating Mode Animation

System is Radiantec's
preferred system
because of these



(heating is provided indirectly by means of a heat exchanger)

Legend for Indirect Heating System animation

When heat is called for, domestic hot water is pumped to the heat-exchanger where the heat is transferred to the heating fluid on the other side. At the same time, the heating zone pump(s) comes on and circulates the heating fluid where it is needed.

The heating fluid is separated from the potable water supply by means of the heat exchanger. A non potable heating fluid such as anti freeze can be used.

Click here to read more about Radiantec's Indirect System.


(This "traditional" system uses a boiler or water heater to heat water)

This system, dedicated exclusively for space heating, uses a boiler or water heater to heat water (or an antifreeze solution) which is circulated through the in floor tubing. This is a familiar and conventional approach that is well accepted by building code officials when a boiler is used.

Legend for Closed Direct Heating System animation

Solar Heating

Radiantec Company supports the use of solar energy whenever it is feasible and notes that solar efficiency has improved greatly in the past few years. This is the most powerful of the Radiantec heating systems. It is a "hybrid" system that combines the best features of "active" and "passive" technologies while leaving behind their respective disadvantages.

The Solar Heating Option is applicable to new slab on grade buildings. It uses the structure's inherent ability to store heat energy and that must be designed in from the beginning.

A solar installation in conjunction with Radiantec's Open Direct System, provides supplemental solar for space heating and domestic hot water needs.


"A significant advantage of the Solar Option I system is that it is capable of meeting nearly all of a residential type building's heating needs, even in quite challenging climates. Another advantage is exceptionally high efficiency that very low operating temperatures entail. "Substantial improvements were noted in system efficiency, overall performance, initial cost and architectural flexibility. An increase in collector efficiency translates into fewer solar panels, lowered costs,and easier design integration into accepted building styles. A large thermal mass, integrated within the building's structure provides prolonged solar storage, radiant comfort and further lowered costs."

-Report to US Department of Energy 1983 (DOE/CE15140-T)

For more information on Radiantec's solar technology, visit www.radiantsolar.com


If you see words and expressions that you are not familiar with, consult this section.

Understanding the meaning of the following phrases will make it easier to understand your heating system options.

A boiler is a heating device that is engineered to make very hot water (up to 250 degrees F, under pressure) for radiators and baseboards. Many boilers do not work well at lower temperatures and may need expensive controls to make the adjustment.
A domestic water heater is engineered to make moderate temperature water. A storage tank is often provided, and additional precautions are taken to prevent corrosion. There is a potential for higher efficiency with a hot water heater because of lower operating temperature and lower exhaust gas temperature, but many low end water heaters do not take advantage of this potential.
A heat exchanger is a device that exchanges the heat from one fluid to another without a mixing of the fluids. A typical use would be to keep the potable domestic hot water separate from the boiler fluid.
A closed heating system is one which is closed off from the environment and its heating fluid is not changed except for maintenance.
An open system is one that is open to the atmosphere or one in which the heating fluid is replaced often. A domestic hot water heater is an open system because the heated fluid is constantly changed. Open systems require different mechanicals and materials.
Potable means fit to drink.
A direct system is one in which the potable hot water in the water heater is used for space heating and domestic hot water for doing dishes, laundry, taking showers, etc. There is no separation between the two.
An indirect system is one in which the heat from the heating unit passes through a heat exchanger before it goes to the in floor tubes.


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Open Direct System
Installing the Closed System
Installing the Indirect System
Installing tubing for a concrete slab
Installing tubing between floor joists
Installing tubing in the ceiling
Installing tubing in the walls
Installing a heated towel rack
Installing Radiantec Controls
Doing your own tubing layout.
Radiantec Basic Solar Domestic
   Water Heater Installation Manual.

Radiantec Basic Solar Domestic
   Water Heater Owners Manual.

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