Theus Solar Thermal System

This annimated graphic shows the components of the solar thermal system and its electrically-powered backup system. The system is divided into three major sections: A drain-back solar hot-water loop which feeds one of two heat exchangers. A solar water tank which provides domestic hot water. A radiant floor heating system that is the building's primary heating system. The graphic is annimated when a pump or valve is operating.

Note that in the actual physical implementation, the bottom of the collector array is more that 10 feet above the drain-back tank and gravity does completely drain the array.

Parameters in bold text are daily totals. Parameters in normal weight text apply to the current pump cycle. The numbers inside the heating tanks show the power and energy used to heat their respective contents. A number with a trailing "*" was produced from solar energy. A number with a trailing "~" was produced from electrical energy. When electrical energy is being used, heating element(s) will appear in the appropriate tank. The solar radiation bar shows the amount of power currently being received compared to the amount expected on this day of the year with a clear sky at the current time. The temperatures in the green ovals are in degrees Fahrenheit. The oval under the tilted solar array is the outdoor air temperature. A temperature in black text should be ignored.

The temperatures in white text are read by the Steca controller and they are used to determine what to turn on and when to do it. The two temperatures shown in orange text are a matched pair of sensors used to calculate power. These values are displayed as they arrive while the power is calculated after these temperatures are run through a filtering algorithm.

The other parameter needed to calculate power is the flow rate, liters per minute (lpm), which is measured by a turbine flow rate sensor. The power drawn by the collector pump is measured by a Brultech ECM-1240 Home Energy Monitor.

The hydronic zone valves take several minutes to open or close. A closed valve is shown in solid red. An open valve with no pump running is shown in solid green. (This can occur when software on the server pre-opens the valve.) An opening valve is shown in flashing green and a closing valve in flashing red. An open valve with a pump running shows a blue animated flow.

Component details and pictures.
Computer monitoring details.