When winter has northeastern Pennsylvania in its icy grip, Michael Long’s house is the place to be.

Long, a third-generation plumber, decided he needed in-floor hydronic radiant heating after installing several of the systems for his customers. When it came time to build his 4,000-square-foot home, radiant heating fueled by propane, a low-carbon fuel, was among the first things he specified.

“It’s the best heat you can have,” says Long, owner of Michael Long Plumbing & Heating, which serves Lehigh Valley, Pa.

Designing an efficient heating system

In a region that routinely sees winter temperatures dip to the single digits, Long placed a premium on heating. A 1,000-gallon propane tank fuels most of the appliances in his home, the most crucial being a 155,000 Btu Aspen boiler, made by U.S. Boiler Company. This is the beating heart of the heating system, distributing hot water through about 14,000 lineal feet of half-inch tubing, plus heating a 75-gallon indirect water heater.

The hydronic heating system divides the house into 10 zones, each with an independent thermostat and manifold for room-by-room temperature control. Even one of his garages (the home has a three-car garage on either side of the house) has radiant heat tubing in the slab and drainage to channel away snowmelt from his vehicles. He keeps the garage at 55 degrees. “It’s nice to have a warm car in the morning,” he says.

Michael Long adjusts the controls on his 155,000 Btu Aspen boiler. The unit heats water pumped through about 14,000 lineal feet of tubing throughout the 4,000-square-foot house, including a three-car garages.

Warming with water

When contractors and clients discuss heating options for a home, there are several good reasons to explore hydronic radiant heat. Here are three:

  1. Efficiency: Water delivers heat more efficiently than air. According to the U.S. Department of Energy, a given volume of water absorbs 3,500 times more heat than the same volume of air. That’s how a 3/4-inch-diameter flexible tube can deliver the same amount of heat as a 14 -by-8-inch rigid metal duct when both systems operate under typical conditions. (Ductwork, by the way, can waste a tremendous amount of energy through leaks and gaps.) Plus, certain flooring materials can increase radiant efficiency. The tile in Long’s kitchen, for example, retains heat.
  2. Even distribution: Forced-air systems can create temperature fluctuations of 3 to 5 degrees between the floor and ceiling. (That explains why your head feels warm while your feet are cold.) In contrast, radiant in-floor heating produces uniform warmth from the floor up. “In computer simulations, laboratory experiments, and field studies, a clear difference is found in vertical temperature gradients between radiant and other heating systems,” says the Radiant Professionals Alliance. “With radiant heating, practically no temperature differences are found between the floor and ceiling.”
  3. Air quality: Radiant in-floor heating doesn’t circulate dust and other allergens like forced-air systems do. That may be a big selling point for people with allergies or respiratory issues.

Long’s home in northeastern Pennsylvania features two three-bay garages, both heated with propane.

Comparing costs

There’s no getting around it: Installing hydronic radiant heating is more expensive than a furnace. But when it comes to long-term operating costs, radiant has the advantage.

“With the amount of square footage that I have to heat, the cost is so much less than it would be with a forced-air system,” Long says.

He estimates he used around 1,800 gallons of propane last year. That’s about a $3,500 fuel bill — not bad when you consider propane fuels not only the condensing boiler for space and water heating but also a gas cooking range, gas smoker, fireplace, and pool heater, plus a ceiling-mounted heater in his other garage, which serves as a workshop.

“It’s cheaper,” Long says. “But more importantly, it’s more comfortable.”