Why Hydronic Distribution Systems Can be Ten Times More Efficient than Forced Air

Policymakers often focus on providing incentives for efficient heat sources, but neglect to do their research on distribution systems.

As a result, they’re missing out on opportunities to boost the efficiency of the overall heating system. They could do this by developing programs that help designers optimize hydronic distribution systems, says John Siegenthaler, instructor of HeatSpring’s Mastering Hydronic System Design course.

Distribution Systems are Not All Alike

“One thing that doesn’t get focused on is distribution efficiency,” he says. Distribution systems use electrical power to move heat regardless of how that heat is produced, he says.

“Water holds huge advantages as far as reducing the electrical power required for heat distribution,” he says. Hydronic distribution systems are typically ten times more efficient than forced air systems.  “With creative designs, it can be better than a ten to one ratio,” he says.

Minimizing Heat Loss with Efficient Distribution Systems

The key is to select components that minimize pressure drops in the system. When fluid flows through a pipe, or air blows through ducts, drag forces consume energy.  That energy has to be supplied by a blower in a forced air system or a circulator in a hydronic system.

In a modern furnace, the blower at full speed might need 400 to 500 watts when the heating or cooling or system is operating. Older technology could be more energy intensive, requiring 800 to 1,000 watts while it’s operating.

40 Watt Systems vs. 400 Watt Systems

“Today, a new modern circulator with a high efficiency motor could operate an entire house on 30 to 40 watts,” Siegenthaler says. “It’s easily a ten-to-one advantage.”

Consumers and businesses are often sold boilers that are 95% efficient or they’re sold high-efficiency heat pumps.

“People focus almost entirely on the generating device and don’t take into account the electricity it takes to move heat around the building. But distribution is where hydronics shine,” he says.

At this time, forced air distribution systems are still more popular than hydronic distribution systems, in part because there are few incentives to support hydronics technology.

Rebates Don’t Support High Efficiency Distribution Systems

“For rebates on things like heat pumps and high efficiency systems in general, the agencies that put programs together don’t look deep enough into comparing the advantages of different types of distribution systems,” says Siegenthaler.

In North America, people are becoming more aware of the advantages of hydronics, he says.  In Europe, hydronic heating dominates the market.

“I do think hydronics is at a point where it could capture a greater percentage  of the market,” he says. “In New York State and at the federal level, there are lots of programs that promote energy efficiency and renewable energy heat sources.  Hydronics is an ideal technology to be blended into these offerings.”

But until hydronic distribution systems get the attention they deserve, consumers continue to choose the least expensive heating option, which is often based on forced air distribution.

Pairing Ferrari Engines with Lawn Tractors

Siegenthaler likens these systems to high efficiency engines paired with less efficient vehicles.

To illustrate his point, he tells his students that he’s going to get involved in NASCAR racing. He’ll go to Italy and buy a top-notch Ferrari racing engine, then install it on his lawn tractor, he quips.

“Taking high efficiency heat sources and combining it with marginal distribution systems is sort of the same idea.  It’s a definite mismatch between an energy source and a method for optimally using that energy.”