It's all about hot water

If you have ever been camping for an extended amount of time there are few things more pleasing than a hot shower. It also makes cleaning up dishes and general washing so much easier...

AJ has made our stay here very pleasant. We've had access to his shop shower ever since our arrival, but we have not had hot running water in the trailer since the hot water heater decided to spring a leak. Last week I took a grinder to the old hot water heater so I could leave the door in place on the RV and still have unrestricted access to the hot water heater compartment. Since that time I have been on the lookout for a replacement water storage tank that I could use for storing hot water heated from a solar hot water panel. So far my search has come up with some possibilities, but nothing that is just right for the job. The easiest thing to do is put another hot water heater in and plumb the solar hot water panel into it so I can make use of the tank, insulation and blow off valve built in. That would also give us the option to have hot water early in the morning or when the sun is not shining. Unfortunately, that is also the expensive option and right now I can't afford to buy a new hot water heater.

There are many companies making solar hot water panels for the home market, but not many (that I could find anyway) that make them for the RV market. I am not looking for something large enough to do laundry and long showers for 4 people. I just need something that will replace the 5 gallon hot water heater that we had. A small 2x4 panel would be ideal, but nobody makes something that small since the major market is the large home owner and they tend to want huge amounts of hot water.

Yesterday I decided to try tackling the solar hot water panel. I did some searching on the Internet for various do it yourself designs that I thought that I could scale down. AJ had a garage full of windows that he let me pick from. I found a 2x4 window that looked like a good start. The window has a wide frame that I think will be deep enough so I don't have to construct a frame for the hot water panel. That saves me some construction and money. The glass is double pane which provides good insulation, but may prove to filter out too much. It's hard to be picky when you're on a serious budget. I removed all of the decorative framing from the window until I was left with basically a box & window. I split off a piece of the frame in the process, so I had to clamp and glue it back together.

While the glue for the window was drying I started constructing a jig for hammering my heat collector. I chose a design that uses little copper and instead uses aluminum for the collector with copper pipe zig-zagged through grooves hammered in the aluminum. I riped some 8" wide 1"x8"x8' wood to make roughly 1"x6"x2' pieces and then screwed them to a table with gaps about the same size as my copper pipe.

I clamped the aluminum at one end and hammered metal rods into the aluminum to force it into the grooves... This proved to be a bit trickier than I had expected, but after a few tries I managed to find a technique that got the job done. There's probably an easier way to do the job...

After hammering in all of the grooves I set the aluminum aside and moved on to bending the copper tubing to match the grooves. I used the same jig that I built for hammering the aluminum. By rounding every board on alternating ends I made a continuous serpentine slot for the copper pipe to follow. I wish that I had made the jig the same size as the panel...

The next step was to bond the aluminum to the copper pipe. I had read that roofing tar might do the job somewhat, so I coated the slots in the aluminum with roofing tar and hammered the copper pipe into them. Experimenting with odd materials and home brewed ideas usually leads to some disappointment. In this case I had a bad feeling about the roofing tar. The pipes kept working their way back out of the slots in the aluminum. I screwed some end boards over the pipe to keep them in place and then coated the pipe/slot joints with a heavy coat of roofing tar. I figured that I'd leave the assembly to dry for a few days to see if it would stick together before trying to move and finish the other half on the jig.

With 1/2 the copper pipe "glued" to the aluminum I set everything in the sun to dry. I couldn't help but wonder how hot the metal was getting, so I went ahead and set up a little experiment... I placed my window frame over the 1/2 constructed panel and ran tubing from a Styrofoam cooler full of water to the panel. With a very small pond pump (approximately 0.25 GPM) I ran water through the panel and monitored the water temperature. We started with 65 degree water and within 15 minutes had 75 degree water. I left it running for a few hours and checked in on it every 15 minutes. There was quite a bit of wind and I didn't seal around the edges of the window frame, so the temperature varied a bit with how much wind there was. The highest temperature we reached was 102 degrees. As a side note - the 100 foot garden hose on the ground produced 109-112 degree water of the same volume in 1/2 the time. Not too encouraging, but I figure that the hose was on the ground protected from the cool breeze and getting a bit of help from the hot gravel driveway.

I am not very impressed so far with the design that I found on the Internet. I will most likely start from scratch and see if I can come up with a better (lighter, more efficient and portable) design. This design weighs a lot and doesn't appear to be that well thought out... I am going to go ahead and finish the panel I started, but most likely it will end up being used on a project where weight is not a concern.