Hydronic heating provides superior comfort

When John Kopf eventually gets around to designing and building his own house, he will go with hydronic heat instead of a more traditional forced air system. Kopf knows a thing or two about heating, having spent more than 20 years in the industry. He currently serves as boiler product manager for Navien.

“The main reason is comfort,” he says. “From a hydronic system, you get even heat distribution. Think of it, most of us — including myself — have forced air heat. We have grills, diffusers and vents in the floor blowing hot air, and usually, those are placed below the windows in cold spots. Around that vent, it’s warm, but as soon as you start moving away, it becomes colder and colder. When you have radiant floor heating, there is a very nice and even distribution.”

Pros and cons

Another benefit to having hydronic heating is no air movement, Kopf notes.

“With forced air, you have air passing through narrow passages like grills and diffusers, there’s dust accumulation, you’re using filters and so on,” he says. “With hydronic heat, there is no air moving, which brings another point: Noise. Hydronic heating is super quiet.”

Boilers are an integral component and the optimal heating source in a hydronic system, says Kal Osman, director of boilers for AERCO.

“With new condensing boilers offering efficiencies in the mid-90% range, they are a great energy reducer for all building types,” he says. “Condensing boilers are compact, making them an ideal heating solution that can be installed almost anywhere, while providing unlimited design flexibilities. Hydronic heating offers flexibility to meet any building’s design, any climate region and any heating delivery mechanism. It also requires less floor space than traditional HVAC.”

Because of the high efficiencies of today’s boilers, hydronic designs are also used to provide domestic hot water heating, which improves overall system efficiency while reducing the overall mechanical equipment space requirement, Osman adds.

Steve Swanson, customer trainer at Uponor North America, believes the major benefit of baseboard heating is low initial cost and low maintenance costs while the major benefits of radiant hydronic heating are comfort and energy savings.

“Radiant heating produces warm floors, which make for warm toes in the winter,” he says. “Radiant heating systems typically produce an energy savings of 30%. Radiant systems also have no drafts, and they are quieter, since there are no fans. Because there are no fans, cooking odors don’t go from room to room. Allergens are not transferred from room to room, either. The key factor driving all of this is that water is 3,500 times better at transferring heat than air.”

While there are numerous benefits to these systems, the main drawback, Swanson notes, is the need for a separate cooling system.

“There are also higher installation costs for radiant heating,” Swanson says. “However, these are offset by fuel savings over time.”

Kopf agrees cost is a deterrent.

“You would typically spend about 25% to 30% more on a hydronic system versus forced air, but then you recoup those through operating savings,” he says. “But a lot of developers are not interested in comfort as much as they are in minimizing the cost. That’s why we have so many forced air furnaces in the U.S.”

“In no particular order, there’s the increasing efficiency and condensing risk with cast iron boilers, steam boiler resilience to increasing chloride content in water and increased functionality and efficiency of boiler zone controls for higher zone counts,” he says. “Additionally, we’re seeing a simplification of controls and combustion settings for high efficiency condensing boilers and improved remote communications access to boilers and systems to satisfy connected homeowners. There is also the issue of condensing boiler reliability as increased use of high efficiency [condensing] boilers is shortening aggregate boiler [all types, both condensing and non-condensing] expected service life. We’re also seeing an increased use of instantaneous combi boilers and DHW recirculation to conserve fuel and potable water.”

According to Kopf, condensing boilers are gaining market share over non-condensing.

“Condensing boilers are gaining momentum and there is nice growth there,” he says. “Eventually, condensing boilers will take over. In Canada, it has already happened. There are very few non-condensing boilers being installed nowadays.”

Additionally, Kopf notes that boiler controls are becoming smarter than they used to be.

“First of all, Wi-Fi remote access is becoming huge,” he says. “Right now, there are a handful of manufacturers — including Navien — that have Wi-Fi devices. Our NaviLink system allows customers to dial in, check the status of their unit, receive alarm notifications, set certain schedules and more. Also, controls becoming smarter means that our controls have some adaptive logic where on a weekly basis, it looks at the occupancy, how people are using it and self-learns the pattern.”

Osman also notes the industry is moving away from traditional non-condensing boilers to smaller, more efficient condensing boilers as part of the effort to save the environment while satisfying current and future building needs.

“Additionally, system design temperatures and moving to higher ∆T designs requires less flow and smaller pumps,” he says. “When combined with sophisticated centralized controls, these efforts improve hydronic solutions sustainability and design, while providing optimal comfort.”

One of the more recent trends in the industry is the concept of low-temperature heating and high temperature cooling, or the marriage of radiant heating and radiant cooling, Swanson notes.

“The vast majority of LEED platinum buildings in the past five years have been constructed using radiant heating and cooling with a DOAS (dedicated outside air system) for make-up air with dehumidification,” he says. “These buildings reduce energy consumption, lower the carbon footprint and provide better indoor air quality, while saving space by eliminating large HVAC ducts. The major thrust of the HVAC industry going forward is sustainability, clean healthy air, energy savings and lower carbon emissions. Radiant heating and cooling is a perfect partner to help accomplish these goals.”

Contractors weigh-in

Farmington Hills, Michigan-based Thornton and Grooms mostly sees hot water baseboard and in-floor, hot water radiant and steam systems in its service area.

“We work on mostly hot water baseboard heating, usually legacy systems in older homes,” says Matt Bergstrom, president of Thornton and Grooms. “They are common enough, in maybe 2% to 3% of the homes in our service area, which is the Western and Northwestern suburbs of Detroit. But, overall, most of the homes have forced air furnaces.”

These systems are attractive to customers because they are clean, quiet — when they are working right — and keeps better humidity in the home than forced air systems without adding a humidifier, Bergstrom notes.

“They heat objects rather than air, which feels more comfortable to most people,” he says. “Usually, these systems are existing or installed during new construction or during a major remodel. Most are new systems going in. Really, the only downfall of these systems is air conditioning because you need to add a whole different system.”

In Stittville, New York, hydronic systems are common, notes Dave Dousharm, owner of CNY Pipeworx.

“I see mostly radiant floor panels and radiant wall panels,” he says. “I think it is so common here because we had a strong local Radiant Professionals Alliance (RPA) chapter here for years. They provided a lot of education to the contractors in this area. Also, the presence of John Siegenthaler here helps.”

While the comfort and efficiency benefits of hydronic heating are great, Dousharm points out there are some downsides.

“Obviously, cost is one,” he says. “They’re generally more expensive than a traditional forced air system. There is a potential for leaks because there are a lot more moving parts. They are also more difficult to service and troubleshoot. But we still generally recommend them during new construction almost every time.

“I’m still seeing strong hydronics market,” he continues. “I do think we’re going to start seeing more electrically driven heat generation for these systems, such as heat pumps. It seems to be the way things are going.”