It's warm and sunny, so I thought I'd post a screenshot from the network-interface for my TDC3-ethernet controller. The TDC3 has a novel method for approximating heat gain (you make an assumption for heat loss, and heat not gained to the cylinder - this varies from cylinder to cylinder, for Navitron cylinders, the coil is very large - 1.6m2 surface area, so it will be efficient, but for standard cylinder coils, much of the heat may be sent back to the solar panel). As a guide, you would expect to lose 5-10%. I have entered 20% losses into the onboard calculation (my system has long piperuns, so losses in winter are higher than normal) - but this is overkill - in this weather I would expect losses to be around 10%.
Here's what it looks like. The 'W' reading is the current heat being gained (whilst the pump is running). The 'kWh' reading is the energy-gain to date (it's only be operating for a few days so far - hence low reading!).
Array: 30 tubes 70mm single-walled
Tank: 260litre vented cylinder
Piperun: 16m each way 15mm
Weather: hot and sunny, 24August07, 2pm
Current number of people staying in house (I have no idea of water drawoff): 6
Ivan
