Powerful engineering simulation and sizing models lie beneath a simple, intuitive, and easy-to-use graphical user interface. This is a free hydronics design software demo that you can use to explore and play around with. We use it in our hydronic design courses. I remember thinking it was funny how every little niche industry has their celebrities, and clearly John was one of those in hydronics and radiant heating.
A few years later I contacted John out of the blue about teaching and we spent an hour on the phone comparing notes, chatting, and brainstorming ways to do something exciting. He was open and enthusiastic — qualities I observe in all of the best teachers I work with. It represents the state-of-the-art in computer-assisted design for modern hydronic heating systems. Powerful engineering simulation and sizing models lie beneath a simple, intuitive, and easy-to-use graphical user interface.
The HDS can help you quickly answer routine design questions such as:. Report Abusive Comment Thank you for helping us to improve our forums. Is this comment offensive? Please tell us why. To make matters worse, assume the boiler has very low thermal mass and that relatively little piping lies between the boiler and its load.
When the lightly-loaded boiler is fired, its temperature quickly rises to the setting of its limit control, at which time the burner shuts off. Because of the low thermal mass in the system, the temperature of the circulating water drops quickly. Within a minute or two, this classic short-cycle is ready to repeat itself.
It's only a matter of time until components fail prematurely due to excessive cycling. One of two things can correct this situation: 1 a boiler with a modulating burner capable of reducing output as the load decreases, and 2 an insulated buffer tank that acts as sort of a "thermal capacitor" in the system, absorbing the excess heat and allowing the boiler to run for at least a few minutes once it's been fired.
A conceptual piping schematic showing a buffer tank connected as a secondary circuit to the primary loop is shown in Fig. Such piping allows the thermal mass of the tank to go on- and off-line as necessary, depending on the control strategy used. Don't 5. Don't oversize control valves.
If 2" piping is used for a distribution system, do you automatically specify a 2" control valve? In almost every case, such "line-sized" control valves are at least one pipe size larger than necessary for the application. This is especially true when the valve is used to mix high temperature boiler water to a substantially lower temperature for a radiant floor heating system.
A line sized control valve can pass all the hot water needed even at design conditions with very little stem movement. The remaining travel range of the stem is effectively wasted, and accurate control under low load conditions becomes difficult.
Control valves should be selected based on their Cv rating, not their pipe size. It's fairly common to select a control valve with a Cv rating equal to the design flow rate it will handle in gpm. This yields a 1 psi pressure drop across the valve at design conditions.
Two-way control valves are often used to regulate the heat output of a heat emitter by varying the flow rate through it. Such valves should be selected so the pressure drop across them when fully open is at least half the pressure differential imposed across them when fully closed. Successful designs demand an understanding and respect for the details and concepts we've discussed. As you sketch out systems, apply them.
As you inspect systems, look for their implementation. As you ponder what hardware to specify, use them as a reference. And finally, whenever you get a chance to enjoy the comfort your systems provide, appreciate how they all work together. John Siegenthaler, P. In partnership with HeatSpring , he has developed several online courses that provide in-depth design-level training in modern hydronic systems, air-to-water heat pumps and biomass boiler systems.
Additional information and resources for hydronic system design are available on Siegenthaler's website at www. This website requires certain cookies to work and uses other cookies to help you have the best experience. By visiting this website, certain cookies have already been set, which you may delete and block. By closing this message or continuing to use our site, you agree to the use of cookies. Visit our updated privacy and cookie policy to learn more. This Website Uses Cookies By closing this message or continuing to use our site, you agree to our cookie policy.
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