In forced-air systems, zoning offers a way to control the indoor environment in several different areas throughout the home in order to meet the occupants’ comfort needs. Likewise, hydronic zoning grants residents control over the temperatures in their living spaces while saving energy in the long run.


“Zoning has improved on the air side over the last few years, and the story on hydronics is similar,” said John Siegenthaler, principal of Appropriate Designs in Holland Patent, New York, and a Hydronics Zone columnist for The NEWS. “We’re at the point now where all the major pump manufacturers offer variable-speed circulators. People call them smart pumps, and these are high-efficiency motors that can speed up or slow down in reaction to changing conditions.”

More efficient pumps allow contractors to design new or retrofit systems that can precisely meet the heating load in each zone of the home. “When hydronic zoning is executed well, you can do it on very low amounts of electricity,” Siegenthaler said. “I could heat a 2,500-square-foot house on a very cold day on 25 W of electricity.”

Barry Nauss, director of sales, Grundfos Pumps Corp., said residential hydronic zoning allows for personalized temperature control where and when a user needs it.

“Simply put, why should I heat my whole house just to raise the heat in my master bedroom by 3 degrees?” Nauss asked. “Today, family heating requirements are so much different than they were years ago. It is not uncommon to have times when the whole house is either completely empty or completely full, or maybe heat is required only in one room or on one floor. Homeowners want to have options, and hydronic selection, or zoning, is a means whereby the user can truly select the comfort level desired by room, floor, or location.”

Hydronic zoning is effective “because it allows a residential heating system to run at its most energy-efficient level by providing the right amount of heat to provide occupant comfort only in the zones being used,” said Andy Januszewski, marketing manager, Armstrong Fluid Technology. “Most new residential hydronic systems are designed with zoning.”


There are a few options for zoning an existing hydronic system, Siegenthaler said. “You can zone with thermostatic radiator valves, which have been around for several decades and go onto a radiator or baseboard, and instead of using an electric motor to operate the valve mechanism, they have a thermostatic cartridge.”

If it’s a radiant system, zoning can be accomplished using manifold valve actuators, he added. “An actuator is basically a motor that screws onto each circuit of the manifold. So, if you had a manifold with six circuits, you’d screw six of these on, and you could wire those to thermostats. Each room would now have its own thermostat and could independently control each circuit on that manifold.”

The retrofit process depends on the existing system installed in the home, said Cameron Vreeland, product marketing manager, Honeywell Intl. Inc. “If there is a zoning system present, it could be adding an additional zone or perhaps upgrading the existing system to utilize newer controls solutions. If zoning is not present, it could mean a complete reconfiguration of the existing system is necessary to incorporate zoning.”

Honeywell provides a complete product lineup to its contractor partners, including zoning controls, pumps, valves, sensors, switches, and more. “The major change to the industry has been the integration of reset controls in boilers by the manufacturers, allowing equipment to maintain lower boiler temperatures,” Vreeland said. “This trend is leading manufacturers to produce simple controls solutions that are making hydronic zoning more accessible for installers.”

Dan Holohan, operator of and a Hydronics Zone columnist for The NEWS, said manufacturers are working to find ways to use as little electricity as possible in hydronic heating systems while also integrating connectivity into their products.

“Thermostats are getting smarter, like the Nest and [Honeywell] Lyric, which know whether or not you’re home,” Holohan said. “Thermostatic radiator valves can now connect to the Internet. My daughter just had these put in. They’re battery-powered, and each room can have a different temperature.”

Circulators themselves are becoming much more energy efficient, Januszewski said. “Armstrong manufactures small circulators that are ideally suited to residential zoning. Whether the designer uses a central circulator with zone valves or individual zone circulators, Armstrong has the right products,” he said. “When used in a multi-zone system using zone valves, our Compass circulator can actually adjust the flow to serve only the zones that are open, resulting in up to 80 percent energy savings compared to traditional, fixed-speed circulators.”

Grundfos’ newest circulator pumps have cut energy use in half, Nauss said. “Grundfos has Alpha or Magna circulators that are designed for hydronic heating and hydronic zoning with pumps that consume at least 50 percent less power than a previous circulator of the same size. The circulators have built-in electronics that can speed up or slow down automatically. This is applicable in hydronic zoning, where zones open and close based on temperature selection. The circulators detect the user’s choice of zones and adjust automatically.”

Additionally, Grundfos has embraced the connectivity trend. “With the Grundfos Magna product, a user can actually email a report of how the circulator is set up and how much power it has consumed,” Nauss added.


While hydronic zoning has been around for many years, technology and efficiency standards are exerting an increasing influence on the market.

“[The future of the market is] something we watch closely at Grundfos,” Nauss said. “The government might mandate that all residential circulators meet energy requirements. Hand-held devices might allow users the option of programming their home’s heat selection remotely. In fact, they already do this, to an extent. Heating systems might one day use advance weather information to set a home’s temperature. There are so many factors that are influencing the hydronics industry.”

Holohan also anticipates federal regulations will soon affect residential circulator pumps. “There’s going to be a lot more smarter pumps that follow temperature differences and pressure differences. We’ll get to a point where they’re mandated, probably once we get past this next election. That kind of puts the circulator into constant-run mode. It changes the way you look at zoning. If every room is comfortable, do you have to have a lot of zoning in the house? I’ve seen houses with 25 zones, and that’s ridiculous. It’s easy to get carried away.”

The use of electronically commutated motor (ECM) circulators is one of the most significant recent technological innovations, Januszewski said. “From a contracting perspective, there are no additional steps on installation, yet the distribution energy can be reduced 50-80 percent. On the circulator side, the use of intelligent energy-saving circulators, such as the Armstrong Compass line, may become the minimum standard of technology allowed, as is the case today in European residential heating applications.”

The installation process is also changing, Januszewski added. “The use of PEX [crosslinked polyethylene] plastic tubing instead of traditional copper or cast-iron pipes is an older innovation that really improved the ease of installation of hydronic systems.

“The market will adapt to a wider variety of heat sources, some with significantly lower temperatures than conventional boiler systems used,” he continued. “As a result, many components need to be adjusted, such as the size of radiators in the living space.”

While hydronic zoning is becoming more popular, Bill Boss, sales director for hydronic systems, heating solutions segment, Danfoss, said, first costs continue to be an obstacle, particularly for retrofit applications. However, he also said installation has been improved by advances in technology.

“Advanced electronics have allowed for increased efficiency for pumps and boilers, which work together with electronic zone valves,” he said. “Newer systems are more likely to be zoned than retrofit. Connectivity and the Internet of Things will continue to drive and influence the market’s development.”

Honeywell is seeing a major shift toward connectivity in many markets across the spectrum and expects the same to occur with hydronic zoning, said Vreeland. “Connected solutions would give rise to simpler retrofit applications and drive more competitive pricing on installation, providing hydronic zoning options for all new customer segments,” he added.

While it is clear technology and regulations are influencing hydronic zoning, only time will tell exactly where they will steer the market.

“Gone are the days of the old thermostat, where you turned the dial up or down to adjust heat in the whole house,” Nauss said. “Most of today’s thermostats can be programmed off and on. Some can even send monthly usage reports and have ‘auto away’ technology allowing them to detect when there is no activity in the area or zone after a certain amount of time. Also changing are the designs of hydronic systems. So, yes, technology has changed and will continue to change as new products, systems, and applications get more and more advanced.”

Publication date: 3/21/2016

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