Articles by John Siegenthaler, P.E.

Zoning has always been a premier benefit of hydronic heating and cooling systems. There are many zoning configurations capable of delivering heat (or cooling effect) when and where it’s needed in a building, with minimal effect on the temperature in other parts of the building. Some methods use circulators to create flow in each zone; others use either motorized or thermostatic valves to regulate flow.

One concept that’s getting increasing attention among HVAC engineers is “resilient design.” It refers to approaches that - ideally - allow systems to remain operational under very abnormal conditions, or minimize effects that could cause major damage to systems when and if they are otherwise rendered inoperative.

While I admit to not being fully informed on the latest things from Google, Apple, Chat GPT, or social media, I’m confident that I can still pass along advice to those who are new to the hydronic industry, especially those involved with designing systems

A building with slab-on-grade heating from a cast iron boiler plans to expand. A monobloc air-to-water heat pump will provide heating and cooling for the new space via a fan-coil unit, with the existing boiler serving as backup.

Air-to-water heat pumps are gaining popularity in North American hydronic systems, but many practitioners are discovering that they operate differently from boilers.

What happens if there’s a simultaneous call for domestic water heating and cooling?

Fortunately, our industry is at a point where the question "But what do I do about cooling?" can be answered, with confidence, and by the same hydronics professional offering heating.

When the system was operated, the owner complained of flow problems. The heat emitters in any given zone were only marginally warmed when their associated zone circulator was operating. The owner questioned if another circulator should be installed.

As electrification reshapes the HVAC market, hydronic-based heating and cooling systems stand ready to offer many design and performance benefits. One of them is the potential for thermal storage. After all, water is one of the best materials on earth for storing sensible heat.

Last month, we discussed direct-to-load hydronic heat pump systems. These systems use a variable-speed compressor and circulator to adjust heat output and flow, eliminating the need for a buffer tank or hydraulic separator.