Drain water heat recovery.

Even after installing high-efficiency water heaters, low-flow fixtures, and practicing water-conservation habits, we're still faced with the fact that almost all our expensive hot water goes right down the drain. What a waste! Fortunately, I learned about Drain Water Heat Recovery (DWHR) devices from a friend who has been using this technology for over a decade, and was able to incorporate a DWHR unit into the barn. The drain water heat recovery system is basically a large heat exchanger designed to recover the heat from your shower water before it reaches the sewer system. The units consist of a large 3 inch copper pipe with smaller copper pipes wrapped around the outside. As your hot shower water drains through the 3 inch pipe it warms the pipe exterior. This heat is then transferred to the cold incoming water which is flowing through the smaller tubing wrapped around the drain pipe's exterior. There are no moving parts and nothing that can wear out- a very simple design and quite effective because there is lots of surface area and copper is highly conductive. By replacing a vertical section of your drain plumbing with the DWHR unit, a large percentage of the energy in the outgoing hot water can be used to 'preheat' the incoming cold water. I installed the DWHR pipe in a small vertical chase on the main floor to capture the hot water coming from the upstairs master bathroom before it goes under the slab. Putting the DWHR pipe in the basement would obviously be preferred, but since this is a slab-on-grade structure we don't have a basement- this is the only way I could incorporate the DWHR unit into the floor plan. I installed the GFX S3-60 model, which looks like this: Before testing it out, I insulated all of the drain plumbing between the sink, shower and the DWHR pipe. Before...

...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.

The final steps on the yellow brick road.

It feels good to be actually finishing projects on the barn lately- this time its the yellow brick road. When standing in the original barn before it was deconstructed in 2007, I always felt that the brick floor gave the building a unique feel. Since the bricks were simply laid on the ground without mortar, it was easy to remove them undamaged, so we saved as many as possible. Some areas were heavily coated with oil and grease from decades of tractor parking, but the majority of the bricks cleaned up nicely using a pressure washer (thanks mom and Lisa!). To incorporate the old bricks into the new floor, I formed a meandering pathway across the new barn slab before the concrete was poured, which looked like this: After the structure was roughed in, I mortared the salvaged bricks into the recessed pathway- it soon became aptly named, the 'Yellow Brick Road". Since the bricks were laid with tight joints, I wasn't sure exactly how to go about the grouting process. Having absolutely zero experience with tile work at the time didn't help- so I decided to leave it 'as is' and come back to it later...that was 2008! Finally, almost two years later, I vacuumed all the debris out of the cracks (which amounted to over 3 gallons of sawdust and wood chips), and got started. I mixed some home brew grout using 2.5 parts sand to 1 part Portland cement- then with my mom's help we worked the powder it into the cracks using an experimental sweeping, rubbing and putty knife-packing technique. This worked relatively well, albeit very messy.

Working in sections, the dry grout was packed into the joint lines, then the excess was vacuumed off the top of the bricks and gently wiped clean with sponges. Once the bricks were fairly clean, I sprayed water over the dry mix using an HPLV sprayer to start the hydration process. We worked from one end to the other in this manner, taking an entire day to do the pathway. I gave the pathway a few more sprayings of water over the next few days, letting the grout set up. Then it required about a dozen moppings to remove the haze of grout that was all over the rough-textured surface (I had put two coats of AFM Mexeseal on the bricks before starting the grouting process, but it didn't seem to help that much). After alot of scrubbing, here's the nearly finished product:

The grout was VERY slow to harden using this method, and required some touch up in certain places where there didn't seem to be enough Portland in the mix for it to set. I changed the sand/Portland ratio to 2:1 for the touch up work and this seemed to be much better...more lessons learned on the rocky road of barn-building.