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The two most commonly installed types of radiant floor heat are Electric and Hydronic
(liquid) radiant floors.
Hydronic tubing immersed in a concrete slab floor or electric heating mats set in mortar
applied over the subfloor are called wet installations.
Dry installations include modular wood panels with precut grooves for hydronic tubing
such as WarmBoard, or electric mats designed for installation directly under carpeting or
hardwood floors. All "between the joists" basement installations using hydronic tubing
or electric mats are also termed dry installations. Another dry method is the use of
baseboard radiators for a hydronic system.
Electric Radiant Floors
Electric radiant floors typically consist of insulation coated cables. The cables can be run
free form in loops over the subfloor or interwoven within a mat. Free form cable
installations are usually immersed in a 1 1/2" gypsum or concrete slab.
When the cables are immersed in a concrete slab a thermal mass is created. The upside
to a thermal mass is once it's heated to temperature it will retain the heat for hours and
requires much less energy to keep it "charged." The downside is warm up time of
several hours.
Electric mats on the other hand are as little as 1/8" thick when covered with mortar and
warm up much faster than slabs. Another installation option for electric mats is to staple
them between the joists under the subfloor as a retrofit "spot" heating solution. Both
free form slabs and mats can be covered with tile, hardwood floors, or carpet.
Although above floor, and under floor mats might look similar, their applications are not
interchangeable. Under floor mats are not designed to be set in mortar and vice versa.
The temperature of electric mats is controlled by sensors and should not exceed 85
degrees F at the surface. 85 degrees is skin temperature and anything warmer starts to
feel too warm. Floor coverings other than stone or tile REQUIRE a maximum temperature
below 85 F. Most people are very comfortable between 75-80 degrees F.
Electric cables or mats will raise the ambient room temperature 10-15 degrees when
installed under hardwood or tile, but only 7 or 8 degrees under carpet.
All in all I think installing electric mats between the carpet pad and carpeting is a bad
idea. Not only is the return on your heating dollar poor, many under carpet installations
are not UL listed. I would not buy an electric radiant heating system that was not UL
approved. Also it's impossible to predict how the electric cables will withstand the weight
of heavy furniture.
Electric radiant floors may also make sense for additions onto homes for which it would
be impractical to extend the heating system into the addition. However, homeowners
should examine other options, such as mini-split heat pumps, which operate more
efficiently and have the advantage of also providing cooling.
Hydronic Radiant Floors
Hydronic (liquid) systems are the most popular and cost-effective radiant heating
systems for heating-dominated climates. Hydronic radiant floor systems pump heated
water (100 degrees F) from a boiler through tubing laid in a pattern underneath the
floor.
In some systems, the temperature in each room is controlled by regulating the flow of
hot water through each tubing loop. This is done by a system of zoning valves or pumps
and thermostats.
A big advantage of hydronic systems is the flexibility of the fuel source. You can use gas,
oil, electricity and even solar energy.
Hydronic systems have high start-up costs because you have to buy a boiler. The
installed cost of an electric floor can more or less be figured by the square foot. As a
result, electric radiant heat tends to be more cost-effective on small floors. The larger
the area you need to heat, the more cost effective a hydronic system becomes.
Here's a thought; if the water for a hydronic system is heated by solar collectors or a
geothermal heat pump you might be able to apply the 30% energy tax credit to the cost
of the ENTIRE system instead of just collecting the maximum $1,500 for a new boiler. But
run it by your accountant and installer first to get their professional opinion.
(liquid) radiant floors.
Hydronic tubing immersed in a concrete slab floor or electric heating mats set in mortar
applied over the subfloor are called wet installations.
Dry installations include modular wood panels with precut grooves for hydronic tubing
such as WarmBoard, or electric mats designed for installation directly under carpeting or
hardwood floors. All "between the joists" basement installations using hydronic tubing
or electric mats are also termed dry installations. Another dry method is the use of
baseboard radiators for a hydronic system.
Electric Radiant Floors
Electric radiant floors typically consist of insulation coated cables. The cables can be run
free form in loops over the subfloor or interwoven within a mat. Free form cable
installations are usually immersed in a 1 1/2" gypsum or concrete slab.
When the cables are immersed in a concrete slab a thermal mass is created. The upside
to a thermal mass is once it's heated to temperature it will retain the heat for hours and
requires much less energy to keep it "charged." The downside is warm up time of
several hours.
Electric mats on the other hand are as little as 1/8" thick when covered with mortar and
warm up much faster than slabs. Another installation option for electric mats is to staple
them between the joists under the subfloor as a retrofit "spot" heating solution. Both
free form slabs and mats can be covered with tile, hardwood floors, or carpet.
Although above floor, and under floor mats might look similar, their applications are not
interchangeable. Under floor mats are not designed to be set in mortar and vice versa.
The temperature of electric mats is controlled by sensors and should not exceed 85
degrees F at the surface. 85 degrees is skin temperature and anything warmer starts to
feel too warm. Floor coverings other than stone or tile REQUIRE a maximum temperature
below 85 F. Most people are very comfortable between 75-80 degrees F.
Electric cables or mats will raise the ambient room temperature 10-15 degrees when
installed under hardwood or tile, but only 7 or 8 degrees under carpet.
All in all I think installing electric mats between the carpet pad and carpeting is a bad
idea. Not only is the return on your heating dollar poor, many under carpet installations
are not UL listed. I would not buy an electric radiant heating system that was not UL
approved. Also it's impossible to predict how the electric cables will withstand the weight
of heavy furniture.
Electric radiant floors may also make sense for additions onto homes for which it would
be impractical to extend the heating system into the addition. However, homeowners
should examine other options, such as mini-split heat pumps, which operate more
efficiently and have the advantage of also providing cooling.
Hydronic Radiant Floors
Hydronic (liquid) systems are the most popular and cost-effective radiant heating
systems for heating-dominated climates. Hydronic radiant floor systems pump heated
water (100 degrees F) from a boiler through tubing laid in a pattern underneath the
floor.
In some systems, the temperature in each room is controlled by regulating the flow of
hot water through each tubing loop. This is done by a system of zoning valves or pumps
and thermostats.
A big advantage of hydronic systems is the flexibility of the fuel source. You can use gas,
oil, electricity and even solar energy.
Hydronic systems have high start-up costs because you have to buy a boiler. The
installed cost of an electric floor can more or less be figured by the square foot. As a
result, electric radiant heat tends to be more cost-effective on small floors. The larger
the area you need to heat, the more cost effective a hydronic system becomes.
Here's a thought; if the water for a hydronic system is heated by solar collectors or a
geothermal heat pump you might be able to apply the 30% energy tax credit to the cost
of the ENTIRE system instead of just collecting the maximum $1,500 for a new boiler. But
run it by your accountant and installer first to get their professional opinion.
Alternative-Heating-Info.com
Types of Radiant Floor Heat
