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Heating Energy Sources

Most radiant heating systems operate using warm water.  It is not very hard to make warm water.  Here are only some of your choices: natural gas, propane (LP), oil, coal, wood, electricity, heat pumps, ground source heat pumps and solar energy.  Radiantec tries to offer products that are highly energy efficient and yet still a smart investment.

Illustratio of a water heater
           The Polaris water heater

Photograph of a Wood or Coal Heater
            A quality wood fired boiler

Combined System

Photograph of a House with Solar Collectors on the roof

Photograph of a house with Solar Collectors on the roof

Gas Fired Water Heater

Please note that Radiantec often recommends the use of domestic water heaters instead of expensive boilers.
Click here for more information about that use.

Gas is readily available and is produced mostly within the United States.  Its price has gone up along with other sources but it is clean enough to use with condensing flue gas technology.

Radiantec Company does not currently advocate the use of so called "tankless gas fired water heaters" for its systems. Click here for a link to our frequently asked questions for an explanation.

"My Plumber friend believes in a hot water boiler, but we used the Polaris water heater and our system works perfectly. Oh yes, we installed it ourselves." -Rick, MA

Oil Fired Boilers or Water Heaters

Oil can be less expensive than gas in some locations at this time. Oil also has more heat value than liquified gas (LP).  However, oil pollutes more and the heating units are not as efficient at this time.  We are not aware of oil fired units that can condense the flue gas, but some are in the developmental stages.

Much of our oil supplies are imports that come from unstable countries.  Some believe that our oil resources should be reserved for transportation.

The price and availability  of heating oil is unstable for political reasons.

Wood or Coal Heaters

These heaters work best when they are allowed to have a prolonged burn time at reasonably high temperatures.

They can seriously pollute when they are shut down with a load of fuel remaining.  They really should have some kind of heat  storage incorporated into the system so that they can be operated at convenient times and with low emissions.

A storage system similar to that of a solar heating system works very well.

The graphic to the right illustrates a popular solar heating system that makes domestic hot water as well as space heat. If you use a wood boiler instead of solar panels, you will have a wood heating system with many advantages. You will make domestic hot water and have the benefits of thermal storage. We also think that the overall system will be safer. Wood or coal can provide energy independence and can be cost effective if you value labor as healthful exercise. But it is very important to burn theseproducts cleanly.

Solar Collectors

It is easy for solar collectors to make warm water.  The low temperatures of radiant allow for good efficiency at the solar panel.  The quality and efficiency of solar heating has improved greatly and the investment value or “payback” can be very good when designed well. 

Nearly all solar heating systems require some way to store the solar heat for times when the sun is not shining. Slab on grade construction is ideal and domestic hot water heaters can be used as well.

In almost all cases, a solar energy system will require some form of “backup” in order to avoid unreasonable over design for long cloudy periods.

You can either “do a little solar”, and use two or three solar collectors or, if architecture permits, use more solar collectors to obtain a higher solar heating percentage of your heat and hot water.  Either way, it is a mistake to “over do” a solar system and create architectural problems.

Solar collectors do not have to be placed upon the house.

Solar collectors that make electricity are coming down in price.

Depending upon climate, architecture, and commitment, solar heating contributions vary from 25% to 95%. Solar Section


Radiant Retrofit

You can add on to a boiler that you already have for baseboard heating.  You will need a mixing valve to lower the boiler heated water for the radiant heat and yet be able to provide the high temperature boiler water to perform the uses that the boiler was designed for. 

It may be desirable to use oxygen diffusion barrier tubing in order to protect system components. An alternative would be to separate the two fluids with a heat exchanger.



Electric heating is not very desirable unless a low cost source is available with low environmental impacts such as hydro. In some cases when only a very little electricity is needed, an electric heat source can make sense.

Electricity is expensive to generate and usually has great environmental impacts. 

Most electricity in the United States is generated either with coal, or nuclear, or fossil fuels, and the efficiency is not high because of the losses from energy conversion and also from line losses in transmission.

It’s use for simple purposes like heating and hot water is to be avoided.




So called geothermal energy sources extract heat energy from the ground with an electric heat pump. The problems are that parasitic electrical costs are usually very high and the purchase price of the system is quite expensive as well.

In a way, the environmental costs of a geothermal system are nearly as high as a straight electrical system and there is no real cost saving when everything is added up.

If the “COP” or “coefficient of performance” can be improved, and costs can be lowered, this approach might make a real contribution; but the numbers are not there yet.



Some heating units require an unreasonable amount of pumping energy to move water through the unit. It would be a shame to buy two highhead pumps and then forever listen to the noise that they make and also pay for the electricity that they use. Modulating gas units are particulary subject to this problem.


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