This report was rather late in being created and published- November 2024!!Our first attempts of heating the bricks up was not robust as the heating wire suffered from metal fatigue, caused by the wires glowing red hot one moment and then cooling down during the day. This is what we discovered when we dismantled several of the trays. The wire was broken in one location or another.
So we went looking on the web and discovered some commercial heating elements that are designed to fit in a domestic storage heater out there somewhere, we didn?t care about that, as these would provide a much stronger replacement than our bare wires. So, we took apart the two layers of bricks, chip off the cement and pulled away the heap of heating wires. We then turned the bricks over so that the hollow part is open upwards and we grinded a series of slots to fit the new heating element in so that the second layer of bricks can come back down flat again.
We connected the spade terminals to the existing wiring and push the spade plugs on to the elements. We reassembled the stack of trays. One thing to note, is that we only replaced eight of the ten trays as the supplier were only selling these elements in packs of four and we didn?t want to take the risk of buying another pack and have two spares. We were not confident enough to know whether it will work or not. Another limitation was the power requirements as each element is more powerful than our original setup, therefore we could only connect one tray to one relay and we had only eight relays in total. So, the bottom two trays were two of the old design and we left them in the stack to act as ballast.
We reassembled the rock wool layers, stretched the wire mesh over the wool and put the front cover back on again. We rewired the relays up on the control board so that the mains is switching just one tray instead of a pair it was doing before.
We fired up and everything is running. We then set the temperature to a deliberately low 200°C and waited overnight. The five trays all heated up nicely!! So, we turned up the temperature to 300°C on the following night. All is ok again. We did 400°C and still ok! And finally, we settled on 500°C and lovely!
You may have noticed that we were only heating up five trays and the reason for this was that our micro-controller chip didn?t have enough output control pins to drive the other three trays.
We have our storage heater back again for this Winter!
We are warm again using cheaper Economy 7 prices!!
Phew!