All-copper construction means the Drainwater Heat Recovery System will last as long as your plumbing system and will pay for itself many times over. Safety is guaranteed by U.L.-approved, double- wall-vented construction and self-cleaning ensures maintenance-free operation at peak efficiency. Installation is not complicated. As illustrated on the left, the heat exchanger simply replaces a vertical section of drain line and the incoming cold water is rerouted to flow up its coil. It can be an ideal do-it-yourself project for those with a familiarity with plumbing, or you can have your plumber do the job, usually for between $100-$200. Shorter models are available for homes lacking the 60" vertical drop required for S3-60.

Click here to see the anatomy of the modern home plumbing system with the Drainwater Heat Recovery System added to preheat all incoming cold water for best efficiency (70KB).

       Sizing Guide and Installation Instructions

Click here to view the Acrobat .PDF file (906KB) documenting the selection procedure and model # nomenclature, as well as instructions for residential installations.

What about slab construction?

In two story homes, the Drainwater Heat Recovery System can service upstairs bathrooms by being installed on the first floor. With existing slab construction, the only way to install the Drainwater Heat Recovery System is to use a pump to divert shower drain water. For new construction, a short model can be installed in a pit. The Drainwater Heat Recovery System will one day be integrated into shower stalls with a pump to reroute the drain water. This is practical, because far less energy is required to pump water than to heat it. For example, a 100-Watt pump can enable the System to recycle 10,000 Watts from shower drain water.

How many units must I install for a 2-bathroom house?

For a house having one bath/shower, two bathroom sinks, kitchen sink, dishwasher, clothes washer, one Unit will do the job at normal cold water supply pressures. The designers of The Toronto Healthy House elected to install two Units, but merely for higher efficiency.

Must the System be located directly beneath a shower?

Hot shower wastewater holds its temperature as it speeds down the walls of a drain pipe at approximately 1 metre per second; falling from a second floor shower to the basement floor in under 10 sec. Of course the drain line will be heated by the first rush of drain water, but the energy to do this in the vast majority of homes will be negligible. Consequently, the Drainwater Heat Recovery System can be located far enough from the shower to service several fixtures. An ideal location is in the main drain where it enters the basement floor.

Why is it important to feed both the water heater
and plumbing fixtures?

  The Obvious Case

Passing just the cold water feeding the water heater through the heat exchanger, where it's preheated by 50 degrees to 40 degrees as the 105 degrees wastewater is cooled by just 25 degrees because there is twice as much of it. This case corresponds to recycling 50% of the heat traveling down the drain. (In practice, the Model F-601 will cool the wastewater by about 20 degrees at 2.25 gpm while recycling about 40% of the waste heat. Lowering the water heater set-point will decrease the flow-imbalance and increase the efficiency.)

  The Equal-Flow Case

Passing water feeding both the water heater and cold side of the shower through the heat exchanger. Now the drain water will be cooled by 50 degrees and the feed water will be heated by 50 degrees because the flows are balanced. This case corresponds to 100% recycling efficiency. (In practice, the Model F-601 would cool the wastewater by about 30 degrees at 2.25 gpm while recycling about 60% of the waste heat.)

  The Confusing Case

Passing just the cold water feeding the shower through the heat exchanger and adjusting the mix to hold the shower temperature at 105 degrees. Now the cold water exiting the heat exchanger will be heated to 105 degrees, so to maintain a 105 degrees shower, the hot water flow must be zero. This case also corresponds to 100% recycling efficiency because the flows will be balanced after the mix has been adjusted. (In practice, the Model F-601 would preheat the cold water to about 89 degrees and cool the wastewater by about 26 degrees at 2.25 gpm while recycling about 52% of the waste heat. Raising the water heater set-point will decrease the flow- imbalance and increase the efficiency.)