Radiant Heating
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Installing Radiant Floor Heat

This radiant-floor-heating system is relatively easy to install, won't leak, and doesn't cost a lot to operate.

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Stepping onto ice-cold bathroom tile is a cruel way to wake up in the morning. It's no wonder so many of us invest in extra-thick slippers and giant bath mats. But what if we were able to shed our slippers and step barefoot onto tile that's toasty warm? Radiant-floor heating makes that possible. And you can install it in your home with far less trouble and expense than you might expect. Radiant-floor heating has been around for centuries. The principle is simple: The floor radiates heat to your feet, warming you all over. Most familiar are hydronic systems that heat your entire house. They produce wonderful heat, but they require serpentine runs of plastic tubing, water heaters or boilers, pumps and manifolds. This makes hydronic systems expensive and complicated to install. A simpler, less expensive alternative for just a single room is one of the electric systems discussed here.

System Basics An electric radiant system consists of thin heating cables, like the wires in an electric blanket, installed under ceramic tile. Because the cables are so thin they don't raise the level of the flooring much; this makes them great for remodeling. They're installed where warm floors are appreciated: bathrooms, mudrooms, and kitchens. Controlled by their own thermostat, these systems don't replace your main heating unit—they augment it. To install an electric radiant floor in an existing room, you'll need a dedicated 15- to 20-amp GFCI-protected circuit to power the system, and an excuse to lay a new tile floor. If you're remodeling, it's a good time to satisfy both requirements. A bathroom-size warm-floor retrofit will cost $400 to $700 including the cost of the new tile. This system will consume about the same amount of electricity as three 100W lightbulbs.

Stepping onto ice-cold bathroom tile is a cruel way to wake up in the morning. It's no wonder so many of us invest in extra-thick slippers and giant bath mats. But what if we were able to shed our slippers and step barefoot onto tile that's toasty warm? Radiant-floor heating makes that possible. And you can install it in your home with far less trouble and expense than you might expect. Radiant-floor heating has been around for centuries. The principle is simple: The floor radiates heat to your feet, warming you all over. Most familiar are hydronic systems that heat your entire house. They produce wonderful heat, but they require serpentine runs of plastic tubing, water heaters or boilers, pumps and manifolds. This makes hydronic systems expensive and complicated to install. A simpler, less expensive alternative for just a single room is one of the electric systems discussed here.

System Basics An electric radiant system consists of thin heating cables, like the wires in an electric blanket, installed under ceramic tile. Because the cables are so thin they don't raise the level of the flooring much; this makes them great for remodeling. They're installed where warm floors are appreciated: bathrooms, mudrooms, and kitchens. Controlled by their own thermostat, these systems don't replace your main heating unit—they augment it. To install an electric radiant floor in an existing room, you'll need a dedicated 15- to 20-amp GFCI-protected circuit to power the system, and an excuse to lay a new tile floor. If you're remodeling, it's a good time to satisfy both requirements. A bathroom-size warm-floor retrofit will cost $400 to $700 including the cost of the new tile. This system will consume about the same amount of electricity as three 100W lightbulbs.

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Installation Details

 

Installation Details

Secure the mat. Plywood or cement backerboard will work as a substrate for the heating cable. Staple into the plastic mat, not into the cable.
Secure the mat. Plywood or cement backerboard will work as a substrate for the heating cable. Staple into the plastic mat, not into the cable.

While you can hire a pro to do a radiant-floor retrofit, it's not a difficult job if you're comfortable setting floor tiles. We recommend that a licensed electrician hook up the new electrical circuit. The objective is to cover the subfloor with a continuous, closely spaced pattern of heating cable, connect it to a thermostat on the new circuit, and cover the cable with thinset and tile. There are two types of cable systems on the market. The SunTouch system uses heating cable that's woven into 1- or 2-foot-wide plastic mats. While the mats can be cut to extend the cable into odd-shaped areas, this system is easiest to use when your installation area is rectangular. The heating cable for the Warm Tiles Electric Floor Warming System from EasyHeat is supplied in lengths determined by layout requirements. The cable fits in slotted plastic channels fastened to the floor at right angles to cable runs. This system has a real advantage when the installation needs to go around curves or extend into odd-shaped corners. The best way to get started with either system is to make a scale drawing of the floor plan and identify the "walking area" where the cable will run. You don't want cable under or against cabinets, a tub, shower enclosure, and the like; it should also be at least 6 inches from wax seals for toilets or bidets. Send a copy of your floor plan to the cable supplier (see Where to Find It). The technical support staff can determine the optimum layout and quantity of cable you need. Standard thermostats are available for each system, but you're better off spending a few extra dollars for a setback model. You'll save energy by cutting heat during periods when the system is in use. Once the cable is down and the wiring is hooked up, all that remains is the tile work. While these systems are compatible with any tile, there are certain thinsets that work better than others; check with the cable supplier for specific recommendations.

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Whole-House Radiant Heating

 

Whole-House Radiant Heating

Trowel on the mastic. The thin profile of the cable and mat allows the cable to be easily embedded in the thinset application.
Trowel on the mastic. The thin profile of the cable and mat allows the cable to be easily embedded in the thinset application.

Hydronic radiant floors are heated by warm water pumped through plastic tubing. Other components in a typical hydronic system include a boiler or water heater, a circulation pump, a manifold of valves to control water distribution, and a thermostat to control temperature. Due to size and complexity, most hydronic systems are installed by plumbers and/or HVAC contractors. The cost for an entire heating system ranges between $6 and $12 per square foot—two to three times the cost of other heating systems. However, a hydronic system offers substantial operational savings when used throughout the house, or at least over an entire level. At this scale, you can save around one-third over what you'd pay to heat by forced air. Carpet, tile, and vinyl flooring can go down over a hydronic masonry floor, although some efficiency is lost if you install a carpet pad. Tubing can also go down beneath a wood floor; it gets installed directly under the finish flooring or fastened to the underside of the subfloor, between joists (see illustrations). The joist-space option can work well in retrofit applications, provided you have access beneath the floor you want to heat.

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Lay the tile. Any type of tile can be installed. Complete the grout work and your floor is done.
Lay the tile. Any type of tile can be installed. Complete the grout work and your floor is done.

Where to Find It Stadler Viega Corporation
3 Alfred Circle
Bedford, MA 01730
www.stadlerviega.com
781-275-3122 Electric cable systems: Warm Tiles Electric Floor Warming System
EasyHeat
31977 US 20 E
New Carlisle, IN 46552
www.easyheat.com
219-654-3144 SunTouch electric radiant floor systems
SunTouch
www.suntouch.net
888-432-8932 Hydronic systems: Climatec Advanced Heating Technologies
Box 3910
Easton, PA 18043
www.climatecadvanced.com
610-250-9885 PFG Industries
9614 Bank Rd.
Vashon, WA 98070
www.mechdir.com
206-463-1267 Radiantec
Box 1111
Lyndonville, VT 05851
www.radiantec.com
800-451-7593 Radiant Technology
11A Farber Drive
Bellport, NY 11713
800-784-0234 WIRSBO Company
5925 148th Street West
Apple Valley, MN 55124
www.wirsbo.com
800-321-4739 Roth Industries
1800 S. Des Plaines Avenue
Forest Park, IL 60130
www.roth-usa.com
708-488-1511 Warmboard Inc.
8035 Soquel Drive, Suite 41-A
Aptos, CA 95003
www.warmboard.com
877-338-5493 - toll free
831-685-WARM (9276) - office
831-685-9278 - fax

 
 

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