...and after. The insulating project is to retain the heat and also for sound abatement, since the bathroom is directly above the dining room. For this I used several layers of foam 'sill seal' material wrapped around the pipes and taped.Here is the vertical transition going into the chaseway:
I noticed most of the water noise was coming from the vertical transitions, so I insulated this area with XPS foam board and copious amounts of spray foam- not pretty, but it really cut down the noise and will contain the heat very well.
The building's incoming cold supply water (from our well water) always passes through the heat exchange unit on its way to the hot water heater, automatically extracting heat from the warm water running down the drain line. When I installed the DWHR plumbing, I added two gauges for monitoring the water temp going in, and coming out of, the heat exchanger: Today, I ran hot water through the shower to see how the DWHR would perform- results look good! With the shower running at 101F, the incoming cold well water was being 'preheated' from an initial 50F temp up to about 72F, capturing 44% of the otherwise down-the-drain heat! The manufacturer claims up to 57% efficiency is possible with this model, but that figure is based on a drain water flow rate of 5gpm- much higher than our low-flow sink and shower will ever provide. I'm guessing that around 40% is to be expected and is still very good. And the best part- the DWHR unit was virtually free- our electrical utility provider offered a $400 rebate for installing this $500 system, so the payback should be less than one year. Even at full price, this appears to be a very wise investment and a great energy conservation project. I'd be curious to hear what results others are having with the DWHR units.