I like your creativity. I've been doing solar thermal systems since the early 1980s. My only concern is in the event of stagnation your collector temperatures could easily exceed 200F. I first got into solar service following the installers mistakes. One example was using 50/50 solder at the collectors. 50/50 melts around 350F or so. I can not begin to tell you how many joints I repaired where the solder melted do to stagnation and the formation of steam .
Dont need Glycol Jeremy...no hard freezes where im at .....so no need for draindown either . My project wont work for space heating because it depends on stagnation only...and circulating the water into a seperate heat exchanger coil / blower would soon deplete the 6 gallon holding capacity of the Collector. My project is perfectly designed for one or two showers around dinner time plus occasional use of the auto. dishwasher .
Originally Posted by jeremyhall.tech.sc
The most ive gotton out of my Collector/Oven is 170 f. and that was a totally sunny day , 100 f . day time temp. in August at 4 pm , with the Collector laying flat on the ground for the high overhead sun .... so i have no worries about uncontrollable super high stagnation temps . given the design of the Pex Coil rolled up the way it is. Now, if the design were changed a bit and the entire 300' Pex Coil were tightly fastened to a large efficient collector plate in one singular row....then you might approach 212 f. boiling point (although the actual boiling point would be considerably higher than that since the pressure inside the Pex is at 75 psi ) .
Originally Posted by acwizard
I can see where low temp. solder could be a problem on very hot copper Collectors ... silver solder or sil-fos would be a wiser way to go .