Tuesday, January 8, 2013

My first 100% Solar Heated Shower

My Beautiful Master Bathroom
I just took the best shower ever! Please allow me to explain. Paul has been puting the finishing touches on the Solar Domestic Hot Water system he built. The last few details included securing the heat exchange coil inside the tank and insulating the outside of the tank. We have been getting some great numbers with the collector (solar panel) reaching temperatures of up to 156 degrees and the tank reaching 106 degrees uninsulated. We held off on insulating the tank until we saw that all the components worked consistently and there were no leaks. The system has been inline and producing hot water for a couple of weeks but the uninsulated tank was allowing most of the heat to escape, effectively heating our mechanical room. This required us to rely on the hot water on demand backup system to heat the water to the desired 111 degrees. Today Paul put 3 of the 5.5 inches of polyiso insulation onto the outside of the tank. Just that much allowed the tank to retain so much more heat that I was able to for the first time switch off the breaker for the on demand water heater and take a purely solar hot shower.

Copper pipes hold the coil in place in the tank
Paul seals the pipe penetrations in the tank

The well water comes into the house at about 50 degrees and first runs through the drain water heat recovery coil. As I shower, the heat from the water I am using is transferred to the incoming well water. We are solar-heating the water and then recycling the heat through the drain water heat recovery pipe. Then the water makes its way to to the heat exchanger coil inside the tank at about 85 degrees. It takes 5 minutes for the water to run all the way through the 300 feet of PEX tubing of the exchanger, all the while absorbing heat from the tank. Today the tank temperature was at 115.5 degrees. The water was nice and hot for my entire 7.5 minute shower. (It takes a while to rinse and repeat with my long hair)  Mind you today was a 40 degree mid winter day with only about 4 hours of good sun. We anticipate that during the longer days of the year, Paul's DIY DHW system should provide 100% of our hot water needs.

The Insulated Tank
The good news keeps coming at OCPH. Although it is not published on their website yet, we received a heads up phone call a couple of weeks ago from the 2012 CT Zero Energy Challenge.Apparently we are the 2012 Overall Winner as well as winner of 3 of the 4 sub categories. Once again, a huge thank you to Jamie and everyone at Wolfworks for helping us realize our vision of building an amazing energy efficient home that we love to live in. Jamie beat me to the punch and wrote a post in his own blog about this accomplishment.

Building OCPH gave us the opportunity to walk the walk and be responsible energy consumers. We are certainly not the most earthy crunchy people you will ever meet but we care about the environment and are mindful of our personal impact upon it. We chose to build a house that we could live with, as well as live in. It would have felt wrong to do it any other way.


  1. that tank is pretty amazing. And the fact that it's home made, all the more so. And seriously, a 7.5 minute shower would be a personal best for me. How can you take such a quick shower? So during the winter, though, you've had to use the on demand heater as your method of heating water?

  2. I see in a later post about the usage of the water heater. It's what I expected, that in the winter it would need to be supplemented.

  3. The electric on-demand supplements the solar hot water year round. Even in the summer there are stretches when the sun doesn't shine for a week.

  4. Great post, thanks for putting the tank details up. How has it been after the years? Any tank leaks? How much supplement is needed? Is your supplement with an electric tank in between your solar tank and the taps? Thanks, David

    1. Hi David, the solar hot water system was built using plans published on http://www.builditsolar.com/. It's been working great. We've averaged about 900 kWh per year of supplemental on-demand hot water heater usage for a family of 4. I'm pretty pleased with this. Water flows through our system as follows: well pump-> drain water heat recovery pipe-> solar hot water tank coil->mixing valve to reduce temp to 120F->on demand heater to raise temp to 115F. I had issues with the product used to waterproof the tank initially by Sani-Tred. In hindsight, I should have followed builditsolar.com's recommendation of an EPDM liner. Once I converted to a sheet of EPDM I have had no problems.