Hydronic Heating Technology: No Longer Grandma’s Clanky Radiators  

To many people, hydronic heating technology conjures up ideas of Grandma’s hot and clanky steam radiators, says John Siegenthaler, instructor of HeatSpring’s “Mastering Hydronic System Design” and other courses.

However, with recent improvements in technology, state-of-the-art hydronic heating systems boast a number of benefits over many modern technologies. They create comfortable heat efficiently. This is especially true of hydronic heat distribution systems, says Siegenthaler, principal of Appropriate Designs and Professor Emeritus of engineering technology at Mohawk Valley Community College.

Hydronics Systems Have Been Around for a Long Time

“A hydronics system is technically any heating or cooling system that uses water or water-based fluid to move heat through the building,” he says. Hydronic systems for heating have been used in one form or another for over a hundred years, including those old cast-iron radiator systems.

Water-based distribution systems yield important efficiency savings over conventional forced-air systems, he says. Hydronics distribution systems (water in pipes) require considerably less electrical energy to move heat throughout the building, regardless of how the heat is generated, says Siegenthaler.

“Just as a rule of thumb, a well-designed hydronic system uses no more than 10% of the energy of a comparable forced-air system just to move the heat through the building,” says Siegenthaler.

Water is Effective at Moving Heat

In fact, water is nearly 3,500 times more effective than air when it comes to storing heat. That’s why a three-quarter-inch tube or pipe can move as much heat as ducts that are  10 inches-by-14 inches. In addition to the efficiency gains, hydronic systems are much less invasive; the small piping is easier to route out of sight.

Hydronics systems are more than just efficient and compact; they complement many renewable energy systems, especially thermal renewable heat sources that already rely on water. Solar thermal collectors, for example, are fundamentally hydronic heat sources. Water or a mixture of water and antifreeze is pumped through collectors to  gather heat. Both geothermal heat pumps and the newer air-to-water heat pumps rely on hydronic distribution systems to move heat through a building.

“A lot of people, when they hear about hydronics and water-based heating, think water-based heating is an old system–like cast iron radiator systems. They think of it as an antique. But modern hydronics technology is leaps and bounds above old radiator systems,” says Siegenthaler.

Hydronics Systems Join the World of High-Tech

They’re leaps and bounds better than old radiator systems in part because microprocessor-based controls and circulators can automatically adjust to different conditions. Hydronics have become as high-tech as any other heating system, he says.

“I’ve been doing this for 40 years, I’ve watched the markets change, and I’m very optimistic that hydronics has a great future in the North American market,”  says Siegenthaler. “Just because you have a high-efficiency heat source doesn’t mean you have a high-efficiency heat system. However, with hydronic distribution systems, many high-efficiency heat sources can attain peak performance, he says.

Siegenthaler, principal of Appropriate Designs, is a mechanical engineer with more than 40 years of experience designing modern hydronic heating systems. He is a hall-of-fame member of the Radiant Professionals Alliance and a presenter at national and international conferences on hydronic and radiant heating. The third edition of his textbook, Modern Hydronic Heating, was released in January 2011.