About Radiant Floor Heating
History and Origins
The concept of radiant floors goes back to Roman times and is today the most efficient and comfortable means of heating residential homes, garages, workshops, driveways and other commercial and industrial facilities. There are two types of floor heating systems – hydronic and electric. Radiant heating supplies listed in this category are for hydronic, or hot-water type heating systems utilizing PEX tubing as means for delivering hot water to the area where heat is required.
Radiant Floor Heating vs Baseboards and Forced Air
Hydronic (hot water) radiant floor heating systems offer numerous advantages over all other systems on the market today, including forced air, baseboards, etc. They are quieter, require little or no maintenance and create unparalleled comfort levels while consuming less energy. Unlike forced air and convection baseboards, radiant heating system ensures a proper heat distribution in a room, keeping the feet warm and the head cool. Floor heating systems are compatible with nearly all types of finished flooring, including ceramic tile, stone, hardwood, laminate, engineered wood and many others. These systems can also be operated using any energy source available - electric, gas, oil, wood, etc.
The most common types of hydronic radiant heating systems are:
In-Floor Radiant Heat Systems
When PEX tubing is installed in a concrete slab, gypsum or other thermal mass, such systems are called “in-floor”. The heat from hot water inside the pipes is transferred to the thermal mass (floor), which in turn, heats other objects in a room. Direct contact of PEX with the cement ensures the most even and optimal heat distribution. In floor-heating systems are most commonly used in basements, ground-level slabs and multi-unit homes with steel frame construction.
Underfloor Heating Systems
When radiant heat is desired in a typical residential home with wooden frame construction, PEX is most commonly installed underneath the plywood subfloor, attached directly to it. The PEX lines form a single loop inside the joist bay, then go to another bay and so on. Heat is absorbed by the flooring above and is further transferred to the space above. These systems require quality insulation to maintain efficiency and are often installed in combination with aluminum heat transfer plates.
Which supplies are needed for a radiant floor heating project?
Besides the obvious source of hot water (commonly, a boiler), every project will require
Oxygen Barrier PEX tubing and a
radiant heat manifold. The remaining list will vary depending on the type of installation:
Nearly all
installations inside a concrete or cement slab call for insulation due to large thermal mass. Some projects will require foam board insulation (if so, consider our selection of
foam board stapler tools) while others can use
reflective bubble type. For large in-slab projects where PEX pipe needs to be secured to rebar or wire mesh, we suggest using the
PEX rebar tie tool - it significantly speeds up the installation.
PEX rails are also an excellent and popular choice for securing the pipe inside the slab.
Below-subfloor (between joists) installations would benefit from using
heat transfer plates and
reflective bubble insulation. If plates are not used, the tubing can be secured to subfloor using either
PEX clips,
tube talons or
pipe clamps.
So-called
"sandwich" installations, where PEX tubing is installed on top of the subfloor and covered with finished floor (hardwood, laminate, etc.) will generally use wither cement/gypsum to cover the pipe fully or plywood boards to which the finished floor will be secured. The first option is technically a thin slab - see recommendations above. The 2nd option will need stamped (non-extruded) heat transfer plates - to equally distributes the heat from PEX and eliminate cold and hot spots.
Which controls are needed for a PEX radiant floor heating system?
As with any type of heating equipment, the temperature in a room is controlled via the thermostat, so any 24V (non line voltage type)
thermostat (programmable, non-programmable, wi-fi, etc. ) is a reasonable first choice.
If a radiant heat manifold is used with actuators (sold separately), or if a different/custom copper or steel boiler manifold with zone valves (24V any brand, any type) is used then the only remaining component is a
zone valve control module which serves as an intermediary between the thermostat, boiler and the valves on the manifold.
If a radiant heat manifold is used without the actuators, the hot water would flow to all rooms unrestricted (except if adjusted manually via balancing valves on the manifold) and the thermostat is wired to the boiler.
Some systems utilize circulators for delivering hot water to designated heating zones (rooms) and such set-ups are called "zoning with circulators" or "zoning with pumps". These would call for a
switching relay, which performs the same function as the zone valve controller, but for 120V circulator pumps instead of 24V zone valves.
