Types of radiant floor heating systems
There are two groups of radiant systems. The first is underfloor radiant systems. These systems are
attached to the bottom side of a floor and use metal reflectors to contain the heat in the floor. The
main advantage of these systems is they can be installed in existing homes which have a basement or
crawlspace without major renovations.
The other group is called infloor radiant systems. There are two main methods of installation. The
first method is called wet installation. This is where the tubing or electric mat is embedded in a
concrete slab or tile underlayment.
The other method is referred to as a dry installation. In this case, the tubing or electric mat is
between two layers of flooring.
A hydronic system can be either an open, closed, or combination system. In an open system, the home's
domestic hot water flows through the radiant system. This is permissible in some areas where antifreeze
is not required.
In very cold areas with infloor hydronic systems, an antifreeze solution is added to the system to
ensure that it does not freeze. In this case a closed system is used to isolate the domestic hot water
from the water/antifreeze mixture. This is also used in systems for ice and snow melting on sidewalks
A combination system uses both methods by adding a water to water heat exchanger.
In all the systems a mixing valve is installed. This valve prevents the temperature of the water that
is supplied to the tubing from exceeding 160 degrees. Temperatures higher than that could damage the pex
It is important that radiant floor heating systems are properly designed. The type of flooring that is
used can have a big impact on the effectiveness of the system. Also, the sizing of the equipment that
heats the water in the hydronic system is critical. Special methods of insulation such as insulation
under the concrete slab are required for economical system operation.