John Siegenthaler, P.E.

Last month, we began discussing the HVAC system installed at my church’s newly-constructed parsonage. In this month’s column, we’ll complete the picture.

The overall objective was to create a complete HVAC system, rather than just a heating + cooling system. The system would provide space heating, cooling, domestic hot water, and fresh air ventilation.

Every year, manufacturers develop new or improved products for the North American hydronic market. Product development planning by those manufacturers depends on several factors. Here are a few of the main considerations.

Multiple boiler systems have been used for decades. They allow full heating capacity to be delivered when necessary, while also retaining high efficiency under partial load conditions compared to a single large boiler.

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.