John Siegenthaler, P.E.

John Siegenthaler, P.E., is a consulting engineer and principal of Appropriate Designs in Holland Patent, New York. In partnership with HeatSpring, he has developed several online courses that provide in-depth, design-level training in modern hydronics systems, air-to-water heat pumps and biomass boiler systems. Additional information and resources for hydronic system design are available on Siegenthaler’s website, www.hydronicpros.com.

Hydronics Workshop | John Siegenthaler

Seizing Control

A simple way of keeping heat available in a dual fuel system.

John Siegenthaler, P.E.

June 10, 2026

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.

Hydronics Workshop | John Siegenthaler

Diagnosing Pressure and Air Issues in Closed-Loop Systems

Simple checks, big insights

John Siegenthaler, P.E.

May 18, 2026

Think about the “long game” when designing or installing hydronic systems. Make the system’s as easy as possible to service. Those who follow will appreciate and respect you for doing so.

The Glitch & The Fix: May 2026

The Glitch and the Fix: Grounded Errors

Can you find the issue with this multi-zone floor heating system?

John Siegenthaler, P.E.

May 5, 2026

An installer is planning a multi-zone floor heating system supplied from a single stage non-modulating geothermal heat pump. Can you identify at least four design flaws or operational issues that are likely to develop if the system is installed as shown?

Renewable Heating Design | John Siegenthaler

How to change the staging status of two heat sources

Who's on first?

John Siegenthaler, P.E.

April 6, 2026

What if your boiler system could automatically switch between heat sources based on energy cost? A closer look at staging logic, relays and smarter system control.

Hydronics Workshop | John Siegenthaler

The air-to-water heat pump summit brought contractors, suppliers, and educators together for hydronic technology

Sold-out summit

John Siegenthaler, P.E.

April 3, 2026

The air-to-water heat pump summit was held on March 4th in Burlington, VT, and attended by over 120 people.

The Glitch & The Fix: April 2026

The Glitch & the Fix: Can you find the problems with this space heating set-up?

Under-umphed

John Siegenthaler, P.E.

March 31, 2026

Can you identify some problems that are likely with this set up, and propose an alternative design to eliminate any such problems?

Hydronics Workshop | John Siegenthaler

Why thermal mass and domestic hot water demand don’t always play nicely together

Hands off!

John Siegenthaler, P.E.

March 18, 2026

When radiant slabs and high-demand fixtures share a heat source, thermal equilibrium doesn’t always favor the shower.

Renewable Heating Design | John Siegenthaler

How do North American and European hydronic systems differ?

John Siegenthaler, P.E.

March 10, 2026

When comparing hydronic systems designs that are common in North America with typical European equivalents, comparisons reveal details that would be beneficial in either market, but are not “traditional” in one market or the other.

The Glitch & The Fix: Troubleshooting hydronic piping mistakes in panel radiator systems

John Siegenthaler, P.E.

March 4, 2026

Figure 1 shows a hydronic system that’s intended to supply four panel radiators, each with their own thermostatic radiator valve and an indirect water heater from a gas-fired sectional cast-iron boiler. The system is designed using primary/secondary piping. The primary circulator operates whenever the space heating load or the indirect water heater call for heat.

Renewable Heating Design | John Siegenthaler

How to use H-pattern bypass valves

Through or around

John Siegenthaler, P.E.

February 25, 2026

Panel radiators operated at low water temperatures, and with minimal fins attached to the rear of the water plate, can emit upwards of 50% of their total output as radiant heat.