Quote:
Originally Posted by gasstingy
This home brew SHW system is great! This looks like how I want to heat my garage and the water for the rest rooms I hope someday to install in it.
If you'd care to add more details of how you built the collectors, designed the .... everything  I'd love to read about it. Did you use a reference manual of some sort that is still available (he says with great hope). |
Sorry no reference manual, just a lot of workshop experience.
Panel details: copper tube 25mm top and bottom headers, 15mm risers spaced every 150mm, this lot is brazed together, 0.4mm thick soft copper foil fins with a pressed groove, soldered to the risers. Sprayed matte black on top surface only with 2 coats of an etch primer. Insulation in the cases is 25mm polyiso foam covered in 25mm foil faced fiberglass insulation, tube holes in cases have rubber grommets so the internal copper-work makes no contact with the alloy case. Cases are 1.2mm thick aluminum with folded sides, welded at joins. Backing is thinner alloy sheet sealed with mastic around edge and pop riveted with stainless rivets to main case body. Glazing is 1mm UV treated polycarbonate sheet, sits on folded lip of case edges with rubber gasket. Top edging is thin alloy angle sections welded together so they just sit over the glazing and screwed into case with stainless self-tappers. Two 10mm breather holes in each panel and a small 8mm hole at the lowest point as a condensation drain
The units are mounted in two rows bolted on wooden support frames, each fed from one end only, this avoids uneven flow distribution rates caused by the the 'Bernouli Effect' along each string of panels (especially in pumped systems), an effect most professional systems installers fail to realize. Each string has its own air bleed and over temperature valve at the highest point. Both strings have a common balance tube at one end to even flows and allow a common connection at the lowest point of both for a thermo-static frost protection valve (note secondary frost protection)
Control system is a 12 volt powered DIY PIC CPU using 1 wire DS18b20 temp sensors to monitor temperatures, because our location gets only 10 or so frosts each year, the primary freeze protection is a solenoid valve opened in bursts of 30 seconds by the controller, dumping near freezing water down the drain, when temp in panels drops < 2c.
Circulation pump is an Ivan Labs ELSID 20 magnetic drive 12 volt DC. Over temperature is handled by the dump heat sink getting switched into circuit when solar heated water > 80c, if this fails then the cpu opens the same valve used for freeze protection for a short period, and if that fails then the thermal valves on each string can open. You do not ever want water boiling in panels, puts too much stress on everything.
It will be obvious that potable water flows through the panels, our water is very good, which is just as well as I like brewing my own beer.
Cheers
Mike