Blending valves - the essential solar component
Also known as a Thermostatic mixing valve, this safety device should be installed on the hot water outlet to the taps to prevet scalding.
Because the energy we are using from the sun is free, we might as well make the most of it. So, by turning the cylinder thermostat to 80 degrees (the point at which the cylinder will stop accepting any further energy), we can fill our cylinder completely full of 80 degree water. Of course, you wouldn't want your water coming out of the taps at this temperature, and this is where the blending valve works it's magic. Installed on the hot water outlet from the cylinder, and connected to the cold water mains, it blends the water down to the desired level. Most valves are fully adjustable between 30 and 70 degrees, and can be adjusted by the homeowner, just by turning the knob on the top clockwise or anti-clockwise (provided they have been installed in an accessible location!) The advantages are 2 fold: - Your hot water from the taps will always be at the same temperature - Your 200 litre store, effectively becomes a 250 or 280 litre store, because for every 2 parts hot water, you are blending it with one part cold Thermostatic mixing valves should always be fitted to twin coil cylinders being used for solar thermal systems
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