John Siegenthaler, P.E.

Although the market for solar thermal systems is a tiny fraction of what it once was, I still believe there are viable applications that could help in decarbonizing thermal energy systems.

When a fixed output heat pump supplies a highly zoned heating or cooling distribution system, a buffer tank is typically used to prevent the heat pump from short-cycling under very low load conditions.   

Last month, we covered the basics of classifying switches and relays based on poles and throws. Once you learn these, it’s easy to apply switches and relays to create “hard-wired” control logic - part two.

ades of dealing with hydronic systems, I’ve confirmed two characteristics that always govern their operation. Both are rooted in the tenants of thermodynamics. Neither should be thought of as mysterious. 

The basics of relays and switches - part one.

Those who evaluate the performance of HVAC source equipment such as boilers, furnaces and heat pumps have to work with a wide variety of acronyms. Some of them were spawned by government bureaucrats, mostly the U.S. Department of Energy (DOE). Others were created through a consensus process based on input from manufacturers and other industry stakeholders.

Several years ago, I had the opportunity of visiting the Mostra Convegno Expocomfort show in Milan, Italy. It ranks right up there with the famous ISH show in Frankfurt, Germany, as a “bucket list” event for those who are passionate about hydronic heating and plumbing.

Over the years I’ve had opportunities to work with several architects. They’re interesting people who have the ability to meld art with building technology. Sometimes the result is more “art,” and sometimes it’s more “building.” In either case, their designs typically get handed off to engineers with the simple request: Figure out how to heat my creation…

Last month, we discussed the role of buffer tanks in combination with air-to-water and water-to-water heat pumps that operate as “on/off” devices. The key concept was to turn the heat pump on and off based on changes in the buffer tank temperatures and not based on thermostats calling for heat.

Given the current upward trend and volatility of fossil fuel pricing, there’s renewed interest in heating using wood pellets. Federal incentives that currently cover 26% of some qualified equipment adds enticement toward purchasing pellet-burning stoves.