Affordable efficient
comfort for cold feet: a radiant heat primer.
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Special distribution units,
called manifolds, channel the heated liquid into
multiple radiant floor pipe circuits. Manifolds are
usually located close to the heated area, although they
can be installed in a mechanical room. Each manifold set
includes a supply (hot) and a return (cooler) manifold.
Manifolds usually include balancing valves to control
the flow of heated water to each circuit, or loop.
Circuits are the loops of specialized PEX plastic or
EPDM rubber tubing that begin at the supply manifold and
end at the return manifold. The combination of manifolds
and circuits heat a defined area that's called a zone. A
zone can be one room or several.
One method, which entails the installation of plywood "sleepers" over existing floors or subfloors, is ideal for new construction or retrofits. This system provides the highest BTU output per square foot--important for rooms surrounded by windows where heat loss is greatest. The "SubRay" sleepers are screwed to the subfloor and tubing is laid between them (see photos). A floor installer then bridges over the system with any finished floor using hardwood, laminate wood products, tile or stone. This method adds only one-half inch to three-quarters inch to the finished floor height.
An electric system is often the best choice for spot heating in areas like a single master bathroom, a hallway, powder room or kitchen. Typically, low-profile electric floor radiant systems are installed right in the thinset used to set a finished tile or stone floor. Warm solid surface floors are popular for master baths, entries, kitchens and sunrooms.
In most instances, installers of electric radiant products first attach a cement backer board over the subfloor. The mats are then stapled or taped to the backerboard and thinset mortar is applied with a notched trowel just prior to setting tile or stone. An option, especially well-suited for remodeling projects where an existing solid-surface floor has no heat, is a new type of electric radiant mat by SunTouch that's approved by UL for joist bay applications. If you have access to the framed underside of the floor, these mats can be secured within the joist bays, just under the subfloor, and then insulated.
Electric mats are commonly installed with programmable controllers that use a remote sensor embedded in the floor to keep your feet at the temperature you select. A controller turns the radiant floor on when the room is occupied and off when it's vacant.
There's one thing to check on with electric products. Ask about electromagnetic field (EMF) radiation. EMF is generated by the flow of electrical current, and although the health impact is hotly debated, most experts advise you to minimize your expo sure. Some manufacturers offer very low, or zero-EMF electrical systems.
Warm the Whole House?
Radiant heating can warm an entire house so that supplemental heat is rarely required. If your customer's budget rules out heating the entire home with radiant, then they'll definitely want to know about the option of having warm floors in just those areas where comfort is most important:
* Masterbathrooms. Feet are bare and floors will be wet.
* Masterbathrooms. Feet are bare and floors will be wet.
* Great rooms or family rooms. Frequently, these rooms have open or vaulted designs where forced air heat would stratify. A radiant floor will warm every object in the room without drafts or noise, and without sending the heat up to the ceiling.
* Sunrooms. Such rooms maybe beautiful to look at, but can be terribly uncomfortable because conventional heating won't keep them warm.
* Kitchens and entrys. Bare feet will enjoy a warm massage all winter long. When visitors arrive, they can leave cold, wet shoes on the floor. And, when they leave, they'll have warm, dry feet on the way home.
John Vastyan is a journalist whose work focuses on the radiant heat, plumbing and mechanical industries. He owns Common Ground, a trade communications firm based in Manheim, Penn.