@Badgardener @jerzone A friend set up a passive heating wall for his garage. I N hemisphere, the wall must face south. Imagine a block wall painted black with vent holes at the top and bottom. Outside of the wall, spaced a few inches away, is a clear wall that goes top to bottom. Sun comes through the clear wall, heats the air in the space between walls, and pushes it into the room beyond through top vents, sucking cold air into the space through the bottom.
I was talking about this to someone else here - I made an experimental set up with basically a cold frame and some black piping, to test the principle. It worked, but my wife wasn't keen on putting it on the front of the house!
@Badgardener @jerzone On a related note, I've also had great success with my "poor man's hot tub." That's a stock tank that uses a sump pump to pump water out, through a black hose in the sun, and then back into the tub. I've gotten my tub up to 110° Without a heater.
That sounds awesome! Have you made any posts about it? I’d love to see it.
I doubt very much we’d get similar results in the uk, but the principle sounds great.
@Badgardener @jerzone As a matter of fact, I blogged about it when I first made it. I can't believe it's been that long: https://aneclecticmind.com/2013/07/11/my-poor-mans-hot-tub/
@Badgardener @jerzone I should add here that a few years ago when one of my neighbors died, the guy who bought his house had to dispose of a lot of his possessions. Among them was a big round stock tank that could easily hold four people. I got it for free, power washed it, and set it up in the yard to enjoy it with a friend. I have not used it since that summer but I'm not opposed to setting it up again. But in all honesty, I'd rather have a hot tub on my deck.