Good Things 1 - The heat exchanger

This puppy is my favourite bit of the whole system: the domestic hot water heat exchanger. The blue tank holds water at 65c. When you turn on the hot tap, a flow valve notices the fact, and turns on a pump. The pump circulates water from the blue tank round the "hot" side of the heat exchanger.

The water in the tap flows through the cold side of it, and reaches the same temperature as the water circulating in the hot side.

The net effect is near instantaneous hot 65c water at 26 litres/minute. When mixed with cold water at the bath tap, this fills a bath in about 5 minutes. There's enough capacity in the thermal store to transfer heat to two full baths of water before it needs a bit of a top up from the heat pumps.

The two white things on the left side are the heat-exchanger pre-heat system temperature sensors that me and Paul came up with. They will be fitted to the heat exchanger.