Radiant Underfloor FAQs



Radiant floor heat is the most comfortable heat available. Warmth radiates from the floor warming our bodies and the objects surrounding us. The radiant heat energy that we pay for rises from the floor to the ceiling instead of being blown in from the ceiling and staying up by the ceiling as with forced air heat, escaping through the ceiling or through open doors.


Radiant used in conjunction with a geothermal system provides a system that is highly efficient, provides unsurpassed comfort as well as extremely flexible.  Geothermal systems are available in forced air as well as hydronic models.  The hydronic models create hot water that can be used for radiant heating as well as forced air heating using a fan coil. 

Radiant floor heat is most effective in basement or garage concrete floors that are either at ground level or below ground level. Garages and basements commonly meet these conditions and have relatively well-defined heat losses. Less common applications include home additions, workshops, storage sheds, small commercial buildings etc. Such structures may have more widely varying heat losses. For such applications contact us with a description of your radiant heat floor plans. We are happy to help you choose the appropriate product.


Unfortunately, there are no low-cost ways to add radiant floor heat to an existing garage or basement concrete floor. If you are building, now is the time to install radiant floor heat.


Zoning a basement or garage concrete radiant floor will require framing thermal barriers between zones before concrete is poured. Otherwise, the efficient heat conductivity of concrete will blend temperature between zones.


Ideally, yes. Unequal length loops create unequal pressure resistance in which the shorter length will tend to more of the water resulting in  uneven heat is the result. For good performance with a radiant system, make sure that each loop is nearly equal in length.


Spacing depends on several variables including the heat loss of a basement or garage area. In residential areas such as basements, 12-inch spacing is most common. It is helpful to space the first few tubes closer together in an area at ground level as in a basement walkout area where heat loss is greater. Likewise, spacing can be wider where heat loss is less, as where the floor is several feet under the surface of the ground, or in the center of a large space.


Basement and garage floor insulation is critically important to keep from losing heat to the outdoors by conduction through the earth, the foundation or adjacent walls. When the radiant heated floor is not insulated adequately, it may cause dramatically increased energy loss resulting in higher energy bills. Also, the radiant heating unit may not have sufficient output for the unintended heat loss.


You decide, depending on your electric rate. Generally, electric rate increases have not approached the continuing steep rise in propane, natural gas and fuel oil prices. Examples: If electricity costs you 5¢ per kWh it would compare to propane at 81¢ per gallon, natural gas at 88¢ per Therm or fuel oil at $1.13 per gallon. Or, if you pay 8¢ per kWh for electricity it compares to propane at $1.29 per gallon, natural gas at $1.41 per Therm or fuel oil at $1.80 per gallon.


It's small, light-weight, but very powerful. It employs patented power-sharing technology. It's 99% efficient. It's UL listed for space heating applications. It allows for self-diagnostics and ease of service.

Additional questions? Contact Terra-Therm today.