Many air-to-water heat pumps now include hydronic-side components and system-level controls, but installers still need a backup plan when those controls go down.
Many air-to-water heat pumps are combined with boilers. In retrofit projects, it’s likely an existing boiler; in new projects, it’s likely a mod/con boiler. The boiler can provide supplemental heat during very cold weather. It can also serve as a backup heat source should the heat pump become inoperable.
Air-to-water heat pumps are different from boilers. As the outdoor air temperature decreases, their heating output decreases. That’s a characteristic of all air-source heat pumps, and it runs opposite to how heating load changes with decreasing outdoor temperature.
The air-to-water heat pumps extract heat energy from the outside air and transfer it to water for space heating and optional domestic hot water.
Daikin ALTHERMA 3 H HT is an all-electric air-to-water heat pump that can provide home heating and optional domestic hot water without burning fossil fuels directly by the system.
John Siegenthaler, P.E. will be providing technical training on design and installation of air-to-water heat pumps in both new construction and retrofit applications.
Efficiency Vermont is partnering with the Associated Building Contractors of VT/NH to host a full day air-to-water heat pump summit in Burlington Vermont.
As air-to-water heat pumps replace boilers in North American hydronic systems, designers must rethink traditional approaches to heat transfer, or risk costly and inefficient installations.
Air-to-water heat pumps are gaining popularity in North American hydronic systems, but many practitioners are discovering that they operate differently from boilers.
Most heat pumps in North America extract heat from outside air to warm interiors, which is why we call them "air-to-air" heat pumps. However, this term is incomplete, as heat pumps can also provide comfort without relying on forced air delivery.
A heating contractor is installing two air-to-water heat pumps as the primary heat source in a large home's hydronic system, keeping the existing boiler as backup. However, problems like heat migration into off zones and corrosion of the vent connector suggest design flaws that need to be addressed.