New video showing "box-of-water" heat exchanger!

YouTube - Tub of Water Solar Heat Exchanger Experiment: Mar. 22, 2010

Looking good Ben. It really makes me want to get that panel I have here out in the open sun! I forgot to plug it back into the timer today, so it didn't get any circulation.

Today, my solar hot water experimentation got a 55 gallon upgrade. I know a guy who works for a company that uses plenty of 55 gallon drums, and he had a few from work. I zipped over to his house on my lunch hour in the Electro-Metro and tossed the barrel into the hatchback. (There was actually enough room in the car for two!)

http://gallery.me.com/benhdvideoguy/...12693933420001

Back home, I cut the top off the barrel, and washed it out as best I could. (It still smells like artificial cherry flavoring…)

I then transplanted the copper coil pipe into the 55 gallon drum and filled it up with the garden hose. I bent the end of the copper tube to drain back into the 5 gallon bucket with the pump.

http://gallery.me.com/benhdvideoguy/...12693933750001

I figure that by heating a 55 gallon drum of water, I am getting a better estimate of what should happen in my 50 gallon steel tank when that is used as the final solar tank.

After a couple hours in the sun, the whole barrel was fairly warm (130 degrees) – not as hot as the the 15 gallon tub got, but still nice and warm.

http://gallery.me.com/benhdvideoguy/...12693934050001

I’ll report back in after the next full day of sun to let you know what kind of thermal heat I get from that.

The odd day or two that I have had decent sun, I got pretty good temperatures in the 55 gallon drum.

I also pulled a pump out of a junk pile and hooked it up. It's a much higher gallon-per-minute model. At the higher flow rate, there seems to be less of a difference in temperature between the panel water and the barrel water. It all seems to heat up slowly, but at the same time.

With the lower speed pump, the water in the panel gets hot quicker. The water from the panel into the barrel is rather hot, but nice and cold when it comes back out of the water. I know that it is the DIFFERENCE in temperature that directly relates to the efficiency of heat transfer. So, I think that the slower speed pump is actually more efficient.

Also, even if the water gets nice and hot during the day, it is still cold the next morning. Nights are still pretty cold in the spring, and the 55-gallon drum is open on top and not insulated at all.

The exciting news today is that I chopped the top off the pressure tank. Today was an "EV Build Day" over at a friends house. We have a plasma cutter over there, so I was able to use it to cut the top off the tank. Now, I should be able to start the work installing copper pipe heat exchangers into the tank. :thumbup:

Plasma Cutter sez: "Ha! Take that you steel water tank!"
YouTube - Tank vs Plasma Cutter!

After wresting with 60 feet of copper pipe, I managed to wind it up and shove it in the water tank.

YouTube - Solar Hot Water Copper Coil Pipe install

http://ecoprojecteer.net/wp-content/...4/DSC_3632.jpg

Yesterday, I installed coiled-up copper pipe inside the steel water tank, and rigged it up to the solar hot water panel. After that, I got it insulated. Not perfect, but fairly good, still knowing I need to be able to get inside the tank some more.

Yesterday afternoon, the weather clouded up around 3:30, and then we had the first real thunderstorm of the year, which seemed to go on all night. This morning, it's cold (50F) and rainy, with no sun whatsoever.

So how is the water? I first checked the thermometer on top (with the tip punched straight throw the insulation and into the water) but the lowest the kitchen meat thermometer goes is 120F. So, I knew that the water was at least a little lower than that. Next, I peeled back the insulation on the lid to slip my hand inside. The water was WARM! I would estimate it to be around 100F. Nights right now are in the high 30's to low 40's. Before, with NO insulation on the 55 gallon drum. The water would be COLD in the morning. Last week was a little colder, and there would actually be ice on the top of the water drum.

So, from frozen to warm with only a small change in weather - wow, what a difference insulation makes. And it wasn't even perfect. The insulation is NOT sealed up as well as it could be. In fact, in the finished version, I intend to seal up every last crack with expanding foam, and the tank will have MORE insulation than a standard hot water tank would have.

Also, right now, the tank is in my backyard. Having it in a 68 degree house should make a fair amount of difference as well.

In other recent experimenting...

For a few days, I ran a stainless steel 12V bilge pump to circulate water through the system. It was nice in that it was powerful enough to self-prime, but the flow rate was so high!

With the high flow rate, the water never gets enough of a chance to pick up heat in the solar panel and time enough to drop it off in the water tank.

So, a few days ago, I bit the bullet, and ordered a Ivan Labs "El CID" water pump. It is a 12V DC model designed to run straight from a solar panel.

I got the pump in the mail today, and hooked it up. The pump has 1/2" standard threads, so I just screwed it straight into the intake end of the panel.
http://gallery.me.com/benhdvideoguy/...12712768520001

A couple of neat things about this pump:
Brushless
Very Quiet
DC Variable Speed
Separate Motor and Pump components

Since it's two part, first you install the bronze pump half, and make sure there are no leaks. THEN you screw the motor half on.
http://gallery.me.com/benhdvideoguy/...12712768570001

There is no physical connection from the motor into the pump, and no seals to worry about. The driver half forces magnetism into the pump half which makes it spin.

The two leads of the pump then go straight to a PV panel. I hooked it up to a 15 watt thin film panel I have.

The pump will run on any voltage up to 20. If will keep pumping (but slower) down two about two watts.

http://gallery.me.com/benhdvideoguy/...12712768840001

Here you can see about how big the 15 watt panel is. I also have a 10 watt mono-crystaline panel that I will test it out with as well.

http://gallery.me.com/benhdvideoguy/...12712768680001

The flow rate on the pump seems really nice. It's more that the little 4 watt fountain pump that I was using, and it's considerably less than the bilge pump. Seems like the water has enough time to pick up heat in the panel, and drop it off in water tank.

Very nice Ben. Glad to see that the SS pump was actually hurting things. Thats the same one we had on the 6x3 panel I was testing. That el sid pump looks really nice!

Awesome project Ben, any updates?

Not really any updates. This was more of a learning/practice/experience sort of thing.

The news is that I got a FREE SOLAR HEAT EXCHANGER TANK!

I'm sure I put up a thread about it here somewhere....