Readers flocked to PM Engineer this year for the latest information on new products and technologies, industry news and market trends. Here’s a countdown of the top 10 articles you read the most in 2021 based on the number of unique pageviews on  

10. Dave Yates: Water heater explosion

In 1921, Chetwood Smith had this to say in the American Water Works Association Journal, “I have seen over 35 explosions from overheating water. The force of these explosions — no one can realize who has not seen them. A 30-gallon range boiler raised to a temperature of 290° F has as much energy as 1.5 pounds of nitroglycerine when the explosion occurs, and I think very few people realize the force of the energy they are storing up.”


9. The importance of improving water infrastructure and security

The United States has an infrastructure problem. We have crumbling roads and railways, neglected public transit, and ports and airports in dire need of upgrades, not to mention the critical repairs needed for water and wastewater systems. The American Society of Civil Engineers (ASCE) gave the nation’s drinking water system a C- on its 2021 Infrastructure Report Card. Wastewater systems scored even worse with a D+.

 As we embark on a new year, it’s important that we reflect on 2020 and the unprecedented level of resiliency we witnessed across the AEC industry as a whole. In dealing with a global pandemic in real-time, we saw more businesses than ever turn to technology to not only keep their metaphorical doors open — but, in many cases, as a means of survival. 

7. VRF versus hydronics

With a considerable volume of contradictory information in circulation regarding the application of different technologies for HVAC systems, this article seeks to explain some of the technical aspects of variable refrigerant flow (VRF) systems, and offer comparisons on the basis of cost and performance to more standard hydronic systems. While some of the material presented here are drawn from industry literature, the majority is drawn from peer-reviewed studies conducted by recognized industry professionals.


6. Demand increases for bottle filling stations

COVID-19 has certainly changed the way people live and interact with their environment. Face masks have become the norm, along with carrying around your own personal hand sanitizer or disposable gloves. This heightened awareness around hygiene has also impacted drinking water fountains and bottle filling stations.


5. Plumbing pros predict market outlook in 2021

The start of a new year always brings new possibilities, and PHVAC industry pros are cautiously optimistic about new opportunities in the coming year.


4. Tankless water heaters used with storage?

Quite frequently I get phone calls and emails requesting sizing help for projects. Many times, they are the common straightforward applications for a restaurant, office building or hotel. These ones feel repetitive, which often make me feel like Phil Connors played by Bill Murray in the movie “Groundhog Day.” You know the movie where he wakes up on the same day over and over to a 6 a.m. alarm with the song “I got you, babe.”

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3. The prescription for PEX

Over the past year, the pandemic has had great impacts on our mental, physical and social world. This has affected every aspect of our lives, from the way we think to the way we work to the way we eat (getting groceries delivered), sleep (some, not so much) and breathe (through masks). This new way of life has also shifted the commercial construction industry, revealing the need for greater hygiene and indoor environmental quality (IEQ) in our health care buildings.

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2. Choosing the right balancing valve

Several different balancing valve technologies exist in today’s market; some are new and some have been around for decades. A working knowledge of the entire range of options will serve you well when selecting the correct approach for your specific hydronic or plumbing system project.

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1. Interest surges for combination water and heating systems

With numerous benefits such as compact sizing, high-efficiency operation and cost effectiveness, it’s easy to understand why the combi-boiler market is growing. According to a study released earlier this year by Global Market Insights, the combi-boiler market is expected to exceed $30 billion by 2026.