|Photo taken in a sunny day November 2010|
I am glad to say that once the AKO thermostat was programmed, the system immediately began to work - activating the solenoid valve and pump. As the day was cloudy and grey, I had to pop the sunbox sensor under my tongue just to make sure that the warm temperature activates the pump, and to check that there is a good hysteresis. We have labelled each part of the system to make it easier to understand.
When several days of readings are taken, they will be on a spreadsheet. As the weather conditions, and the surface area of the panels will be identical to those of Nottingham, it will be an ideal comparator with the existing Surya Sunboxes on the Peveril Solar house. You can see from the photo that there is a shading problem in the late afternoon, and there will be partial morning shading from the trampoline. But we can live with that - the boxes can endure partial shading OK.
These black collectors are steel, with convection fins at the rear - a very high total surface area and better admittance than plastic, so we have hopes that this system will outperform the Peveril sunboxes.
David's system has boreholes supposedly of 60m deep, but he is not sure if he has two or three! Even if it is only Two, he has greater capacity to send and receive free solar heat. He has also been running his heat pump for some years with a house twice the size, so the deep ground offers a better delta-T for any warm liquid we send down.