Dammit Manny...

[matt walker]

So, I'm replacing the windows, right? I was at the hell that is Home Depot Thursday night picking up the third window for the living room, and thought I'd get a run of drip tubing for the new berms. Guess what I found on the drip aisle? 500' of black 1/2" tubing for $44.

Got the window home, took out the old one Friday morning. Realize the old casing sides were 47.5" and I had enough of them to make two boxes. The old center panes coming out are 48" sq. You can see where this is going....

Here's a photo from just now, those windows were in the house yesterday morning.






As I was killing myself getting them on the roof, and wondering when and where and all that about the next project, the reservoir. Oh, duh.........






So, I've got a little 12v pump and the solar panels are right there. Maybe I'll have a hot tub tomorrow!

[matt walker]

Ok, it's circulating, maybe 5 gpm or so. I'm getting almost 20°F rise now at 11 am. Sweet.

[matt walker]

I measured the flow, it's more like 2 gpm. I'm getting 10 degree rise at that rate right now, and the tub has gone from 62 initial temp to 89 right now after 2.5 hours or so. Neat.

[mannytheseacow]

Right on! Dang it didn't take you long to get that going.

I'd say the hell with a hot tub. Throw another roll of black pipe in the hot tub for a heat exchanger and run your household hot water through it. I can't imagine how many gallons that hot tub holds. Put a cover over it and insulate the daylights out of it. Just think what a huge thermal battery you have there!

And your pump is running on solar too? Sweet!

[matt walker]

Yeah, the hot tub was/is headed to the dump whenever I get the gumption to create an ecological disaster trying to get it out of where it is. I think the trouble of trying to convert it/insulate it for full time use is not worth it, since I really want that space for more growing eventually. Plus it's a giant plastic wart. I am over it, but it sure is convenient for playing with right now. Now that I've said that just wait, it will be December and I'll still be running it.

Anyway, yeah, this is pretty exciting. It was so simple and cheap and harvested a TON of energy yesterday. In the six or so hours it was in the sun and running that tub went from 62 to 94 and the panels were still producing 99 degree water when I shut it down at 6 or so. I totally do plan on getting another 500' coil to use as the exchange, and now that I'm thinking about it it probably will end up in the hot tub for a bit until I can finish up some other stuff and head down to the basement to build the permanent storage tank. How big is yours, Manny?

[mannytheseacow]

Mine is slightly under 250 gallons, and perfect size for our water heating needs. If I were to do it all over again though, I would just go on Craigslist and pick up one of those 275 gallon IBC totes. We have tons of them around here and you can usually pick them up for 30-50 bucks. Do you know what I mean? They're like a plastic cube inside a metal cage. Just build a foam box around it and you're good to go. You could even use that metal cage for anchoring your pumps and piping. I'm getting ready to pick one up for the rain water system on the barn.

[matt walker]

Gah, another benefit of living in Big Ag country! Around here those things are about a buck a gallon at the farm stores, so the used market stays high as well. Still, I'll keep my eyes peeled. We have more Fish Totes, which are like giant Rubbermaid totes. The only limitation for me is if it's too big I can't get it downstairs. Do you think insulating and storing outside would be a no go?

Oh, and yesterday I did not get the 12v pump hooked up, I was running the tub's circ pump. It has a convenient hose bib for draining down low after the filter, so I was just looping the system off of that, which worked great. I went and purchased some wire last night, and now the 12v pump is doing the circulating. It's a tiny pump, as big as a film canister, and was $19 off Amazon. I can't believe it's pushing up to the roof and through all the coils, but it is, at about 1gpm. Not bad, and my clamp meter says it's drawing .73 of an amp at 12v at that rate. Awesome.

[mannytheseacow]

Wow, it is truly amazing that you are getting that change in water temperature out of such a small pump. I wonder if the slow flow doesn't make the system really efficient. My 110 pumps are sending a lot of water through my panels fairly quickly. I should try setting a variable controller on the power supply and see if slowing down my flow doesn't actually heat faster on less energy.

As for keeping the tank outside, actually the system that mine is designed after was outside. He had a 500 gallon homemade tank that was insulated and set into the ground. It was like a coffin shape. That system was in an unheated building in Montana. An insulated underground line ran from the tank into his house for space heating. Next time I'm at my computer I'll try to share a link to the site (just on a portable device now). I think the ground would be some added insulation and also offers the benefit of acting as you structure to support the outward pressure of the water on the side walls.

[matt walker]

Hmmm, interesting. The tub already has a couple inches of sprayed foam on the shell, and a surround I could fill with wool or something. It's actually almost right on top of the water heater too, like the location almost couldn't be better. Okay, hmmm.

I too am blown away by the little pump, it's this one:

http://www.amazon.com/gp/product/B00DWO ... UTF8&psc=1

Actually, I'm just flat out blown away by this simple system. So, it's 4:30, the tub was uncovered last night so I started the pump this morning with the tub at around 72°F. Right now, the tub is 100°F on the nose, and the return from the panels is still 110°F. It's crazy, it's just stable at this rate all day. This cheapo, thrown together system has put a TON of energy into that tub in the last two days, and at this point needs no inputs. I'm amazed. That little pump is silent, as well. So cool.

[pa_friendly_guy]

Your winters are fairly mild there Matt. If you do not want to have a hot tub could you use the hot water to heat your green house? One of those 250 gal tanks would be a great heat sink to keep your plants warm in winter. How hard is it to drain the solar collectors if you feel it will be cold enough to freeze? If the price of the plastic units is too high could you use a 275 gal used oil tank to store you hot water? Since you will not be drinking the water any thing could be used as a storage tank in the green house for heat storage. Just another thought about ways to use that much solar heat.