TestimonialsComfortable and healthy heat:"I have Wirsbo Radiant Floors in the master bathroom addition. I was pretty skeptical and really didn't understand how a radiant floor worked. It turns out now my master bath is the coziest room, en my in the house. Even my kids go in there after sledding and lie on the floor to warm up. If I had known how wonderful it is, I would have put it in other parts of the house too. I have never been this comfortable. I adore it." Rosemary Connell Shoreham, NY
Provides a comfortable, even heat:
Keeps walkways and driveways clear: Warm Every FootRadiant Floor Heat Tops In ComfortWhen I decided to build my own home this year, I wanted to make the most of every square foot. That meant making the walk-out basement as livable as possible. The more I researched it, the more convinced I became that hydronic radiant floor heat was the way to go.
It may sound extravagant to install two heating systems in a house, but consider this: Real estate appraisers and brokers value main-level space much more highly than basement space. With radiant heat making my walk-out basement as comfortable as upstairs, I figure its like doubling the size of my main level. Besides, everyone I know who has had radiant floor heat in a home assured me it was the most comfortable heating system they had ever experienced.
"The human body is most comfortable when the head is cool and the feet and lower extremities are warm. That's why radiant floor heat feels so good," explained Keith Kelley of Radiant Concepts. His company designs hydronic heating systems for builders and homeowners and helped with my project (see SOURCES).
Some radiant floor heating system manufactures prefer that their systems be left to trained, certified installers. But there are companies like Radiant Concepts who are certified installers and also design systems for do-it-yourselfers for a small fee. They also show you how to prepare the site and install the tubing.
It typically costs about $4.50 to $5.00 per sf for a contractor-installed radiant floor heating system complete with boiler and thermostatic controls for each zone. The design and rough-in portion is about $1.75 of that square foot cost. A do-it-yourselfer can save about 60 cents per sf (about $1,200 in my case) installing the tubing himself.
Design considerations Install a separate zone for each room so you can regulate the temperature as needed. Try to keep the amount of tubing about the same for each zone. Because the water in the tubing will be warmest at the beginning and coolest toward the end of each zone, run the tubing to the coldest part of the room first (usually along the window wall) to heat the space most efficiently and evenly. You also can regulate room temperature through the spacing of the tubing. For instance, space the tubing 6 in. OC along exterior walls and in bathrooms, where there is greater heat loss or higher demand for warmth. Then shift to 12-in. OC in the middle of the space. To achieve this without allowing any sections of tubing to cross, you might have to position a few runs of tubing 6 in. OC along an exterior wall, then continue the run 12 in. OC and perpendicular to the wall. "Spacing is based on the heat loss of the room. That's why an energy analysis is so important," Keith explained. "An internal room may have very little heat loss. But as you get to the side with all the windows, you want go 6 in. OC to compensate for the energy loss." Keith laid out my tubing plan so no tubing would cross under walls. "Tbere's no sense heating areas that will be covered with walls, and it eliminates the possibility that you will screw or nail a wall plate into the tubing," he said. To be honest, when I first saw Keith's zone plan it was like looking into a box of ribbon candy, with different-colored lines looping back and forth on themselves in different directions. I worried about how I would recreate the maze for my new floor until I understood the relationship between the tubing and the wire mesh that supports it. Before you install the tubing, level the ground with sand or rock and insulate it with 2-in.-thick extruded polystyrene insulation, staggering the joints as you would subflooring. Then lay 6-in.-OC wire mesh over the insulation in the opposite direction.
Contractors often use long rolls of wire mesh, but we used 4 x 8-ft. panels because Keith said they are safer and easier to handle. "The problem with rolled mesh is that it can uncoil and whack you when you least expect it, and it always wants to curl up," Keith said. "The panels are easier to place and they lie flat." We secured the tubing with lightweight aluminum ties with looped ends. We chucked a bent nail into a cordless drill/driver set to the lowest clutch setting, hooked both end loops on the drill and let twirl 'til tight. Terminating the two ends of each zone at the manifold couldn't have been easier with the compression fittings. Just do yourself a favor: Slip the compression nut on the tubing before installing the compression ring. Don't ask.
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The system features a boiler, a pump and a series of valves that control the flow of warm water
in cross-linked polyethylene (PEX) tubing that runs through the concrete slab. I still put a
traditional forced-air HVAC system on the main and second floors because I wanted central air
conditioning in those areas and because radiant heat can cause hardwood floor problems in very
cold climates.
Hydronic radiant heat enables you to control the amount of heat not only room by room, but foot by
foot. Unlike convection or conductive heat radiant floor heat remains at the floor, so it actually
is like heating cubic foot by cubic foot. Radiant heat is ideal for basements because it puts the
heat where you need it most: The room stays warmest near the floor and coolest near the ceiling.
Do it yourself
Most heating systems are assembled with dozens of joints, whether they are nested sections of HVAC
duct or a maze of copper pipe and soldered fittings. Radiant hydronic heat is different because it
uses continuous loops of cross-linked polyethylene tubing that start and end at a central
distribution system called a manifold. We were able to install 7 zones and a total of 1,600 ft.
of tubing with only 14 compression fittings, all completely exposed in a 1-sf area of my new
basement.
Installing radiant heat isn't rocket science, but you really need to know your way around hydronics
and energy to size your boiler and lay out the tubing for efficiency and comfort. For instance,
no section of tubing can cross over or under another section because it would create a hot spot.
I gave Keith Kelley a copy of my building plan and told him how I planned to use each space
(shop, recreation room, bedroom, bathroom, sauna, storage). A couple weeks later, he presented me
with a color-coded scale drawing that showed the position of the central manifold and the
placement of every inch of tubing. It also specified the amount of tubing and the boiler size I
would need.
Once you understand a few basic rules of hydronics, it's easy to follow the reasoning behind a
professionally engineered plan.
If you are careful how you install the wire panels, they create a perfect grid for laying out the
tubing. Since the grid is 6 in. OC and the tubing is spaced either 6 or 12 in. OC, you can lay out
the tubing by simply following the wire.
