Do I need a Thermostatic Mixing Valve (TMV) for my diy solar heating system?
When fitting a diy solar heating kit it is always best to err on the side of caution. An optimised solar system will easily produce water in excess of 60 degrees C during the peak summer months. At this temperature, scalding could occur, especially in the case of the young or elderly. So fitting one or more TMVs to the hot water supply is vital. And you must fit a valve compliant with the industry TMV2 scheme. I would recommend to research the flow rate achievable through the TMV in conjunction with the water pressure (head) available prior to purchase. Some TMVs are only capable of delivering adequate flow rates to a single point (i.e. one tap) and are not adequate to supply the entire property direct from the cylinder. Also be aware that any if plastic push-fit fittings are already used within the DHW installation they are usually rated for 65 deg C maximum. Therefore the distributed water temperature must not exceed this temperature.
