Over-pour radiant heat installation. Photo: stepbystep.com
Comfortable, even, and efficient, radiant heat systems are becoming a popular option for many homeowners today. But there are a number of factors that come into play when considering radiant heat, including the type of radiant system desired and whether the installation is for new construction or retrofit.
There are two basic types of radiant heating systems-hydronic and electric. Hydronic systems are the most common; these systems use hot water passing through tubing to heat a space. Electric radiant heat uses electric cables or mats for the same purpose. There are four basic types of radiant heating installations: in-slab systems that are installed in a new cement foundation when it is being poured; an “over-pour” installation, where the tubing is installed on an existing foundation and then covered by an additional layer of cement; joist track systems that fit in between existing floor joists; and wood panel track systems that can be installed over existing subfloors.
A number of specialized components are required for radiant heat installations, including the tubing itself. “When installing a hydronic radiant heat system, most of the time you'll want to use an oxygen barrier PEX tubing to prevent rusting of the cast iron components in your heating system,” notes Daniel O'Brian, a technical expert from online retailer SupplyHouse.com. “This oxygen barrier tubing is what carries the hot water through the flooring or track system and transfers the heat to the space.” There are many brands of oxygen barrier tubing available, explains O'Brian, including Uponor, the highest quality, Rifeng, the least expensive, and ThermaPEX, which offers the best combination of price and quality. All of these brands of radiant tubing carry a 25-year warranty and require PEX tools and fittings for installation.
Rifeng Stainless Steel Radiant Heat Manifold from SupplyHouse.com.
Another necessary component of radiant heat systems is the manifold, which serves as a hub from which the hot water from the boiler is distributed to different tubing loops throughout the house. These manifolds often come with special features, including balancing valves and flow meters, temperature gauges, shut-off valves, and actuators.
The main “engine” driving the radiant heat system is, of course, the boiler, and there are several options available depending on whether you are retrofitting an existing home or building a new house. “For new construction, a condensing boiler would be ideal,” O'Brian says, because the lower temperatures radiant systems require make efficient use of a condensing boiler's capabilities. For a retrofit without a condensing boiler, he notes that “a mixing valve would be required to mix the hot boiler supply water with the cooler return water to achieve the desired radiant water temperature.”
Heat transfer plates are another important component, and these also differ depending on the type of installation planned. “Uponor Joist Trak panels or Ultra-Fin suspended panels are popular for retrofit applications because they are installed between joists-which is generally easier than ripping up the floor,” O'Brian points out. “For new construction, you could consider using Uponor's Quik Trak or the similar Warmboard floor panels. Quik Trak is a low-profile option that can be installed on top of the subfloor, while Warmboard's heavier, thicker panels can be installed as the subfloor. For installations in concrete, you would need proper slab insulation, and you'd likely want to use bend supports where the tubing leaves the slab to protect the tubing against possible friction due to expansion and contraction.”
Uponor's Quik Trak Radiant Heating System package from SupplyHouse.com
While most of these components can be purchased separately, there are also specialized radiant heat packages that offer homeowners a simplified approach to an installation project. Radiant heat packages are available for installations ranging from 250 to 2,000 square feet and come in several styles, including Joist Trak, Quik Trak, slab, and suspended pipe applications. Slab packages are the least expensive, priced from $267 for 250 square feet to $2,132 for 2,000 square feet; suspended pipe packages range from $427 for 250 square feet to $3,570 for 2,000 square feet; Joist Trak packages start at $1,072 for 250 square feet and go up to $6,614 for 2,000 square feet; and Quik Trak packages are the most expensive, ranging from $1,532 for 250 square feet to $11,095 for 2,000 square feet.
There also are numerous accessories available for radiant heating systems. O'Brian recommends radiant thermostats that are compatible with a floor sensor. “Standard thermostats can cause the heat to overshoot the set point,” he explains. “Overheating can cause damage to wood floors and just be plain uncomfortable to your feet. With a floor sensor, you can either set a temperature for the floor to reach, or set a max temperature so the floor does not overheat.”
Online retailer PexSupply.com offers a large selection of products and packages for installing radiant heating systems from the top manufacturers in the industry, and features a variety of product calculators, informative articles, and instructional videos on its Web site. For more, visit PexSupply.com.
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