Today, we have these three little suitcased-sized units hanging on the wall. (picture from last night before the work was finished) On the right- a Rinnai Tankless water heater- Japanese made, computer controlled, tiny little thing that cranks out 180,000 BTU's/hr almost instantly on demand. The copper coloured portion on the top is the heat exchanger. At the top is the double walled flue, bringing combustion air in the outer layer and exhausting through the middle. Now our house is no longer under negative pressure and we should have much less infiltration than before.
Our house has 80 year old cast iron radiators and pipes, and the crap in it would gum this up in a day, so we have set it up as a closed loop, running it through the heat exchanger, middle suitcase. There is also a loop connected to the domestic water- this will supply our hot water for washing and the shower. This unit only has enough capacity for 3.7 gallons per minute, more than enough for a good shower that never ends but we will have to be careful about turning on other taps in the house at the same time.
The left suitcase is a luxury item- a small tank with an electric coil to keep a little water at hot water temperature. Evidently the computer in the Rinnai gets confused running both the heating and the shower and runs home to momma for a few seconds, delivering a cold jolt of water to the showeree. This buffer tank eliminates that shock.
Our expectation: going from 60% to 90% efficiency on the boiler, saving a third of our gas right there. Not having a grossly oversized boiler: more savings. Not heating hot water when we are not using it- more savings. Not paying rental on the tank- more savings. Not putting combustion air up the chimney and replacing it with frigid outside air coming in around 80 year old windows: more savings. Cost is high four figures; Expected return on investment: two to three years, better than most would see but our system was particularly awful.
One can talk about hybrids and wind power and alternative energy sources but the best source of energy is conservation- get rid of the old crap, get modern efficient appliances, change incandescent to compact flourescent, the simple and logical solutions can reduce consumption and greenhouse gas generation. We don't want to tear down our 80 year old houses or wrap them in styrofoam, but we can do a lot to make them more efficient.
Thanks to Brad and Jamie. 1996 website at ::Ecotech Hydronics