Solar Hot Water

there is a bewildering array of options out there when it comes to Solar Water and Space Heating technology. While this competition is a good thing, it often means the prospective buyer is recommended a product based on the consultant's personal preference, rather than perhaps the best choice of unit for the job.

RECENT DEVELOPMENTS

There are a few newer types of collector available now that there were ten years ago, and while some of them can produce dramatically better low light or winter performance than older, simpler types, there is often a more complex control mechanism involved. You might think of the difference between running a lawn-mower and a Ferrari. Above is a photo of a recently installed evacuated tube solar collector. This is definitely the Ferrari in this example. It requires careful sizing of components and a well installed pressure vessel to take up the expansion in the glycol mix which acts as the heat transfer mechanism.

In this installation the tank manufacturer supplied the differential; thermostat which energizes the 20 watt circulation pump. The expansion tank in seen in the right of the picture with the pressure gauge below.

UPDATE

this installation was designed by us but adapted by the plumber and has in fact never worked properly. There is too much heat output so when the tank boils after a few days there is nowhere for the steam to go, the pump deadheads and the system dumps boiling glycol and stalls permanently.

The original design we proposed involved a 6 Cu M (6000 liter) concrete storage tank in the ground to take surplus heat which is then used for building heat in autumn and spring, and to assist the gas in winter. The plumber originally refused to install this, saying it couldn't possibly work (despite being best practice in many European Installations). After two years of back and forth between the plumber and Dux (who supplied the Tank, and in the end gave up) we are reverting to the original idea.

Watch this space.