Fundamentally there are three types of radiant floor heating systems: electric radiant floor systems; hot water or hydronics radiant floor systems, and radiant air floor systems (the heat is carried by an air medium);. Every one of these three types may be broken into smaller groups based on the kind of installation: those that make use of the large thermal mass of a concrete slab floor or gypcrete concrete spanning a wooden subfloor (these are called “wet installations”); and the ones where the installer places the radiant floor tubing in between two layers of plywood or attaches the tubing under the finished floor or subfloor (“dry installations”).
When it comes to this information we are going to concentrate on the hot water or hydronic radiant floor heating system.
Hydronic Radiant Floors
Hydronic (liquid) techniques tend to be the most desired and cost-effective radiant heating systems for environments with extended heating seasons. Hydronic radiant floor systems push heated water from your boiler through tubing laid within a pattern below the floor. In certain systems, the temperature in each room is controlled by governing the flow of hot water through each tubing loop. This is achieved using a system of zoning valves or pumps and thermostats. The cost of installing a hydronic radiant floor varies by location and in addition is dependent upon the size of the house, the type of installation, the floor covering, remoteness around the site, along with the cost of labor.
So-called “wet” installations embed the cables or tubing in a solid floor and they are the oldest type of modern radiant floor systems. The tubing or cable can be embedded in a thick concrete foundation slab generally found in slab style homes without any basement or basement and garage floors or perhaps in a thin layer of concrete, gypcrete, or other material installed on top of a subfloor. If concrete is used and the new floor isn’t on solid earth, additional floor support might be necessary due to the added weight. It’s a strong recommendation that you need to consult an established engineer to check the floor’s carrying capacity.
Thick concrete slab systems have high heat capacity and therefore are suitable for storing heat from solar energy systems, which may have a fluctuating heat output in addition to geothermal heating sources or on demand tankless boilers. The down-side of the thick slabs is their slow thermal response time, that makes strategies such as night or daytime setbacks difficult or perhaps even impossible. Most experts recommend maintaining a consistent temperature in homes using these heating systems.
Attributable to recent innovations in floor technology, so-called “dry” floors, in which the cables or tubing run in an air space underneath the floor, are actually gaining in popularity, since a dry floor is faster and less expensive to install. Take into account that because dry floors involve heating an air space, the radiant heating system is required to operate at a higher temperature.
Some dry installations involve suspending the tubing or cables under the subfloor in between your joists. This method usually requires drilling across the floor joists to be able to install the tubing. Reflective insulation must also be installed under the tubes to direct the heat upward. Tubing or cables can even be installed from above the floor, between two layers of subfloor. In these instances, liquid tubing is normally fitted into aluminum diffusers that spread the water’s heat throughout the floor in an effort to heat the floor more evenly. The tubing as well as heat diffusers are secured between furring strips (sleepers), which carry the extra weight on the new subfloor and finished floor surface.
At least one company Warmboard has improved on this idea by designing a plywood subfloor material manufactured with tubing grooves and aluminum heat diffuser plates built into them. The producer claims this product produces a radiant floor system for new construction or remodeling projects considerably less expensive to install and faster to respond to room temperature changes. The Warmboard products also permit using half as much tubing because the heat transfer of the floor is greatly improved over more common dry or wet floors. You can learn more by going to my website where I do have installation videos on Warmboard and all other types of PEX radiant floor heating systems.