This is part two of a series of post about my solar hot water system. Make sure to follow along!
I built my house in 2012 (five years ago as of this writing). It is a small, super insulated home. The first few months we lived in the home we had only an electric water heater, 50-gallon tank style. It worked great. But, there was one final box to check before being 100% done with the build. I needed a sign off by a HERS rater. After paying this guy almost a grand he failed my home. I was shocked. He actually told me if I switch out the electric water tank with a propane one then I will pass. There was no way I was doing that. So, I wound up installing a heat pump water heater and getting the final sign off about six months in.
Original Water Heater, 50-gallon Tank, Marathon Line.
Heat Pump in blue, tied into original tank.
My wife and I hated that heat pump. We had been spoiled with the electric tank those first six months, but now our water would fluctuate in temperature during just one shower. The system was noisy, I mean really noisy. In our small house there would be no quiet space. It cooled the house, and then I had to run the electric heat more often to heat it. I monitored the electrical use and found no (total household) energy savings. So, I began looking at alternatives.
Solar thermal seemed like the answer, and I was experimenting with a single flat plate collector I had bought. There was also a nice section on my south-facing wall to mount panels. I considered adding a dedicated solar tank with heat exchanger and a glycol system. However, it would require more space in my loft for the additional tank. At the time, we were expecting our first child and my thoughts were on how to turn the loft into a bedroom.
In the end I decided to make a drain-back system. I would build a large, wood framed tank in the crawlspace under the house. Then I could remove the electric tank in the loft creating more space to make a bedroom.
I pulled my inspiration from the website www.builditsolar.com Thank you to Gary who runs the site, and all the people who have contributed over the years. It is a tremendous resource.