Hello Everyone! Very excited to begin commisserating with such a creative and talented people!
What I have come to share with you, and perhaps gain perspective on, is the continuation of a
project which has just taken an interesting turn.
Some time back, I began to build a Domestic
Solar Water Heater to offset some of the electricity my family of five has been using. To do this, I dutifully studied the information available at Builditsolar.com, a treasure trove of information if you don't already know. My inspiration came from the idea that I could re-purpose a natural gas
hot water heater to be used as a heat exchanger in a drainback solar thermal hot
water system. As envisioned, my system would cap off the inner cavity of the water tank, and tap both the top and bottom with fittings so the water from the Solar Thermal Collector could flow through it, pre-heating the 50 gallons of water in the domestic water part of the tank. The water would then move, on demand, to the conventional electric hot water heater. Ideally, this setup would only require the conventional hot water heater to keep the water up to temp.
I soon realized that this system was sorely limited by the size of the hot water storage so I devised a way to daisy chain a series of 4 poly drums to hold pre-heated water in case there was so little demand on the system that I could "bank" some of that heat.
I was quite happy with this setup, but, being winter, I had not yet built the solar thermal collector.
That's when the
Rocket Mass Heater crashed upon the scene.
I have a basement fireplace with a broken flue damper. It occurred to me that this might very well be a nice spot to build a
Rocket Mass Heater and bench/daybed, using the chimney as the vent. In my mind I skipped ahead. What if it gets too hot to sit on???
So I devised a plan to embed pex tubing in loops within the
cob mass. The Thermal Differential Controller from the Solar Hot Water system can handle extra inputs, so I figured the addition of another temperature sensor in the cobb, near the part of the cobb that comes in contact with a person, could be used to control when water would be routed through the pex and back into the hot water storage. In this way, the temperature of the cob bench can be controlled, and I can optimize my solar collector angle for mid-summer, since the
RMH will be doing the heavy lifting for water heating in the colder months. I know some people are wary of combining RMH with water heating, but I don't think it would be an issue in this application.
I do not expect these temperatures to be high. Certainly not
enough to make steam. I'm not really certain how hot a cob bench gets.
As an aside. If someone would offer any sage advice on the above ideas, I would love to hear it. Also, I am somewhat uncertain as to how I
should insulate under the firebox. I assume, pink foam board would be fine for under and in back of the bench, but what do we use under the J-tube area to keep from spalling the
concrete floor, or loosing our heat due to heatsink? Would the higher temperature resistance of Polyisocyanurate insulation board be a better choice for the area just after the burn area? Anyone used it in a RMH construction?
If anyone would like any clarification of these ideas, I'd be more than happy to do that.
Thank you in advance.
Thomas
