Here’s a countdown of the top 10 articles you read the most in 2021 based on the number of unique pageviews on www.pmmag.com. 

Taco Comfort Solutions wins the AHR 2023 Innovation award for Sustainable Solutions with its System M. I fully expect to see a virtual explosion in the number of air-to-water heat pumps on display at the upcoming AHR Expo in February.

Over the last few years, I’ve written several columns describing how air-to-water heat pumps can provide heating, cooling and domestic hot water for homes. Many of the systems involve buffer tanks to help stabilize heat transfer from the heat pump to a zoned distribution system.

Heat pumps offer attractive solutions to energy-efficient heating and cooling, and the market is growing. According to a November 2021 report from the International Energy Agency (IEA), nearly 180 million heat pumps were used for heating in 2020, as the global stock increased nearly 10% per year over the past five years.

In last month’s column, I presented a “template” for a system that provides space heating, cooling and domestic water heating using a cold climate air-to-water heat pump as the primary heat source, and the sole source of chilled water for cooling. 

The versatility of modern hydronics technology allows designers to create systems that are “customized” to the needs — and constraints — of almost any building.