I’d read very little about drain water heat recovery (DWHR) systems prior to this weekend, but after seeing it referenced in some Energy Star documentation I decided to look into a little further.

Put simply, a DWHR unit captures heat from your waste drain water and redirects it back into system. It’s estimated that it can recycle up to 60% of the wasted heat, save up to 40% on water heating costs, and reduce your home’s overall energy consumption by 5-10%. It would be entirely cliched to say it’s saving money from going down the drain, but that’s more or less what it’s doing.

The technology is actually quite simple, and I must admit that I’m surprised it’s not mandated on all new home construction. A portion of the main-stack drainpipe is removed and replaced with the DWHR unit. The unit itself is simply a large copper drainpipe wrapped with a series of smaller copper tubes. The smaller tubes are connected to the cold-water supply, and the water running through them will see a temperature increase of up to 14°. This decreases fuel consumption simply because it requires less energy to heat the warmer water. Similarly, it works incredibly well with tankless hot water systems, which are known to perform poorly when the groundwater is overly cold.

I don’t believe there are many drawbacks with such a setup, although I’ve read claims that water pressure will drop once the device is installed. Apparently the “second generation” units present no noticeable drop in pressure, and I doubt they’ll have an affect on the PEX manifold system we’re considering.

From what I can gather, there are 3 different models available in Canada:

• Power-Pipe [from RenewABILITY]
• Eco-GFX [from ECOInnovation]

• LC-GFX [from GFXTechnology]

  The systems all look more or less the same, although there are a few key differences. The Power-Pipe appears to have more transfer tubes running in parallel, which I believe helps maintain pressure. The LC-GFX site actually scares me a little, and I couldn’t help but notice the conspiracy propaganda that litters it (stolen trade secrets, Energy Star hoaxes, and fraudulent tests?!). That said, it is significantly cheaper… although one has to wonder why (I picture an angry old man, bitter at the world, building these things in his basement).

  Prices seems to range from $400 – $1200+, but they qualify for up to $260 in government rebates. To qualify for a rebates, the DWHR unit must be at least 30% efficient (43% for the maximum rebate), and to qualify for the Energy Star certification, it must be a minimum 48” in length.

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