Retro Fit Radiant Heating Into Your Older Home
Imagine yourself curled up at home on a typical cold, rainy Northwest autumn afternoon. You put your feet to the floor, expecting the usual bone-chilling arctic freeze. Instead, your toes touch a warm surface that radiates gentle heat up toward your limbs like asphalt on a summer night.
This is radiant floor heat.
Another plus to radiant heating is that it can be installed in the ceiling, floor, or walls.
The Romans didn’t have the Oregon chill to reckon with, but they were the first on record to catch on to the benefits of heating from the ground up. They used wood-fire exhaust to warm their raised stone floors to radiate heat to the rooms above.
Two millennia later, Portland homeowners are discovering the comfort of radiant floor heating, which HVAC experts agree is unparalleled.
While the city of Portland doesn’t track radiant systems per se, permit office technician Andrew Millard says he’s definitely seeing more applications. “A few years ago we saw almost none of them,” he said. “Certainly they’re an in-vogue item these days.”
Radiant floors work on a simple design. A heat source – typically a domestic hot-water heater warms up the water. A pump circulates the warm water through a lattice of tubing, which may be tacked to the underside of the floor, or, alternately, embedded in a layer of concrete flooring. As heat transfers out through the piping, the entire floor becomes a giant low-temperature radiator, commonly in the range of 80 to 90 degrees F.
This type of system, using steel and copper piping, was popular in the United States up through World War II. In the ’60s and ’70s, however, labor costs rose and forced-air systems, which could double for air-conditioning use, elbowed radiant heat out of the market.
With a radiant heating system you can re-claim the space in your basement.
Just when radiant heat appeared to be on the brink of extinction, however, a new material rode to the rescue: cross-linked polyethylene tubing, a.k.a. PEX.
Also used for plumbing, PEX is flexible, inexpensive, easy to install, and can take the pressure and temperatures required for heating use. The result: a resurgence of interest in warm floors.
Benefits of radiant systems are legion. First, there’s comfort. While the typical furnace system heats the air in a building, radiant systems heat objects, including people. They also keep the heat close to the ground, where our toes are, instead of letting it drift up to the ceiling. The result is a temperature curve that’s close to the ideal (see diagram above).
In addition, radiant systems avoid re-circulating air, which reduces dust and allergen flow. They don’t exacerbate the draftiness of leaky vintage houses. System operation is virtually silent, and, because water holds heat much better than air, they require much less space to move warmth around the house. say goodbye to cumbersome ductwork.
Heat Distribution Comparison Heat distribution with forced-air is uneven. Most of the heat is concentrated at the ceiling. With radiant floor, the heat is concentrated at the floor where it is needed. So, you are comfortable at a lower thermostat setting... that saves money on your monthly fuel bills.
“I can transport – easily – 10,000 BTUs through a half-inch pipe,” says Eric Sherman, designer of hydronic systems for All Temp Professional, a Portland heating contractor. “A [forced-air] duct would be something like five to six inches.”
In ideal installations, radiant floor heat can also shave up to 30% to 40% off heating bills, though not all users see these benefits.
Tom Kelly, owner of Neil Kelly remodelers, sees a fair amount of demand from clients for the systems. Bathroom floors are a special favorite. “It’s kind of the neatest heating there is, if you can afford it,” he said.
Affording it is the bugaboo of radiant heating today. While costs vary widely depending on the specifics, homeowners going for a retrofit can expect to pay roughly double the cost of a good-quality forced-air system. In one example, the preliminary estimate for a 900-square-foot Portland bungalow came in at $8,000 to $9,000.
Installation time is the biggest factor, says Sherman, the system designer. “It’s much more labor intensive,” he says. For a typical old-house retrofit, installers must drill one and one-half inch holes through all the floor joists to run tubing.
Some resources exist to help homeowners who want to tackle the job – or parts of it – themselves. With a cooperative contractor, the adamant do-it-yourselfer could reduce costs significantly by taking on some of the less-entertaining, more time-consuming tasks while still leaving the calculations to a pro.
Just finding a contractor can be a challenge. “We really don’t have a lot of competition,” Sherman states frankly. All Temp saw a lot of its HVAC colleagues dabble in radiant heating during the mid-’90s, but most swiftly realized that the math didn’t work out for them. “Right now, it’s really good for buyers, ’cause what’s left are guys who have been successful,” Sherman says.
Sources for Radiant Heating Information
http://www.eren.doe.gov/consumerinfo/refbriefs/bc2.html
This consumer information sheet from the U.S. Department of Energy provides an excellent overview of radiant-heat issues.
http://www.thisoldhouse.com/toh/heatingcooling/article/0,13422,216711,00.html
Richard Trethewey, HVAC specialist with This Old House, offers his take on the advantages of radiant-heat systems.
http://oikos.com/esb/43/radiantfloor.html
Oikos, an information clearinghouse on sustainable design and construction issues, gives a green-building perspective on radiant heating.
http://www.radiantec.com/
Radiantec, a Vermont company, specializes in design assistance and complete, factory-direct equipment packages for radiant floor do-it-yourselfers.
http://www.radiant-floor-heating.com/
For the hydrophobic, Warmly Yours manufactures electric radiant floor heating products Ð like an electric blanket for your floor.
http://www.spnwsupply.com/
Shelter Products NW of Tigard is the locally based radiant-heat supply company.
