Maybe there will be news stories of people on the ground being showered by shattering glass from above as these systems reach 30 years old, and the odd one stalls for a fair while then restarts. As vac tube collector costs are dropping, and more such systems get installed, this becomes increasingly likely.
heh, well the first 2 would cut heat input as well as pump run, but the
3rd could indeed prove quite a problem. I can imagine Mary frantically waving at a huge eagle to get it to go away. :)ha, yes. I'm not convinced vac tubes are the best option, with high cost, poor performance on overcast days, and greater fragility. I'm more inclined to favour minimal cost collectors, I think thats where the future of sdhw lies.
Have a good one
NT