Day 45 - Limey

Back in 2005 when we were looking for a new central heating system, all the heating specialists who came to quote said it was not worth having solar water heating panels on the roof - too costly for just two people.

However when we eventually went for a wood pellet system, we did have a 300 litre warm water boiler with the connections in place for solar heating and also for an electric immersion heater.

Since then it has annoyed me every summer to hear the pellet system fire up just to heat a bit of water. Not just the pellets used but also all the electricity driven components of the system.

So now with the PV system, I saw the chance to rectify this. On checking the website of the boiler manufacturer, they offered one for around 400€ but I had seen no name basic heaters for around 50€. Unsure if our PV would cope, I thought it best to go with the cheap system at least until we had some experience of how well it worked. Stefan the electrician was not enthusiastic. "You need a proper 400V expensive one and not a standard 230V plug in thing that will probably not even make a cup of tea."

Secretly I bought the 50€ bit of kit and today told him of my plan. Head shaking but an OK lets try it. He had a Bluetooth socket with which the heater would be controlled by the PV system and set about the wiring.

In the meantime I set about emptying and cleaning the boiler. I think the manual says it should be done at least every two years. Hopefully all readers do this? Out with the sacrificial anode which basically "wasn't any-more and then open up the inspection hatch. Some 6 or 7 litres of limescale was removed but given our dreadful problems with limescale on taps, kettle etc I was surprised it wasn't more.

In with a new sacrificial anode, screw in the immersion heater, close the hatch and fill up 300 litres of 12°C water. About 4 hours later the thermostat on the immersion heater switched itself off at 60°C.

Even Stefan was astonished. In the coming days he was to be so convinced that he has ordered a system similar to ours for his home. He already has a solar water system but this will be taken down and replaced with standard PV panels with a battery and an immersion heater. The roofer who built himself a new low energy house a few years ago with just a sitting room wood fireplace with a hot water boiler behind it and then solar water panels on the roof is also now looking at replacing it.

It will take a few days for the PV system to "learn" our needs and adjust it's methodology of balancing weather forecast, battery usage, our hourly electricity usage of standard equipment, lights etc and accordingly give the immersion heater it's power. Writing this 40 days later, I can report the pellet central heating hasn't switched on once,  we haven't used any bought electricity and always had hot water. Quite fascinating.

Collage shows old and new sacrificial anode - new one is actually 10cm shorter than original. The limescale at the bottom of the tank. The immersion heater in place, looking upwards through the tank - there is still some limescale at the top which I couldn't reach.