Geothermal Radiant Heating Systems

Dan Frawley

Dan Frawley

Lessons Learned by Dan Frawley

Eagle Mountain is an alternative energy integrator. In plain and simple terms we are experts at combining multiple systems together. A prime example of this is pairing a geothermal heating system with radiant heat delivery. This type of system is something that we get inquiries about all the time.

Most people are under the impression that you cannot combine these two types of systems. They think that because a geothermal system is a low temperature heat source, radiant would not be a viable heat delivery method.

Those people would be wrong.

Geothermal heating with radiant is a great way to heat your home. You get all the benefits of radiant heat combined with all the benefits of Geothermal. The most common implementation of geothermal radiant heat systems is in a new build, but it is fairly common to have inquiries in regards to retrofits. Retrofitting geothermal with radiant poses its own set of issues and there are some common misconceptions that go along with that.


First, lets take a conventional radiant retrofit. You and your spouse decided that you no longer want a forced air system. Whether it’s due to allergies, wanting of warm feet on your stone floor etc, you have decided to take that step. For most retrofits, unless it’s a complete renovation, most people don’t want to rip up their existing flooring. So what is the best option? To install the radiant material in between the floor joists using heat transfer plates and astro foil, a solution we call underfloor radiant.

Underfloor radiant does not work with Geothermal. A conventional boiler is capable of producing hot water at about 120-140 degrees. This makes transferring heat through the sub floor and flooring material much easier.

The geothermal heat pump is capable of making a maximum of 115-degree water. This temperature is not nearly high enough to adequately transfer heat through the subfloor and flooring material.

A geothermal radiant heat system works best when paired with radiant slab or an overfloor radiant system. The reason that geothermal  works with slab radiant is that a concrete slab is a great heat transfer medium and it is great at holding on to the heat that is transferred. Due to its heat retention capabilities, a lower temperature heat source, such as geothermal, has enough heat energy to bring that slab up to temperature.

A great example of this is Eagle Mountain’s Center for Green Technology which utilizes slab radiant with geothermal. This 22,000 square foot building is heated quite sufficiently with our geothermal system.

A geothermal system is a low temperature heat source and installers need to keep this in mind.  Forced air is not the only option for heat deliver.

DO – Use geothermal with in-slab radiant
DO – Use geothermal with Overfloor Radiant
DO – Consider geothermal radiant for a new build or retrofit
DON’T – Use geothermal with underfloor radiant
DON’T – Use overfloor radiant without heat transfer plates

Geothermal radiant heating systems are a great option whether you are building a new home or retrofitting your existing home. Our experts at Eagle Mountain are available help you design a geothermal radiant heat system for your new home or your existing home. Call us at 1-800-572-7831 with all your questions.

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