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Green Building News

Drain Water Heat Recovery Gets a Boost in Ontario

This energy-saving technology is now a recognized part of the province's building energy code

Drain water heat recovery gets a boost in Ontario with changes in the province's building code. Builders will now be permitted to use the technology to meet energy-conservation requirements.
Image Credit: Renewability Energy Inc.

Ontario has become the first province or state in North America to recognize drain-water heat recovery (DWHR) as part of its building energy code. Provincial builders will now be able to use DWHR to meet energy-savings requirements in the Ontario building code, and the change also should prove a boost for manufacturers.

Drain-water heat recovery is a way of extracting heat from hot water that’s dumped down a drain — from a shower, for example. The units, which cost an average of $600 to $800, according to one Canadian manufacturer, consist of a copper heat exchanger that replaces part of a conventional drain line. Copper tubing wrapped around the outside of the pipe carries incoming water and allows it to pick up the heat of the drain water that’s exiting the house.

According to RenewABILITY Energy Inc., manufacturer of the Power-Pipe, adding DWHR will lower total energy costs for new homes by about 10% and lower water heating costs by at least 20%.

The company said the change in Ontario sets the stage for similar moves in other parts of Canada and the United States. The technology has already been adopted in France and the United Kingdom and is expected to be approved in Sweden as well, the company said.


  1. User avater
    Dana Dorsett | | #1

    Definitely works- most cost-effective at higher energy prices
    When I installed one in my own home a handful of years back residential-retail natural gas was a buck fifty/therm (delivered) and looking to climb, but now they're bouncing around in the buck-a-therm range. My reasons for installing one had as much to do with boosting showering performance on my combi-heater setup during simultaneous calls for space heating than mere fuel cost savings, and I'm happy to have both.

    Several states will subsidize them for folks heating hot water with electricity (IIRC NY, CT, OR, VT, MN, WI, all have either statewide or local utility rebate type subsidies available, maybe some others), but not so much for those heating water by other means. But showering families heating hot water with resistance electricity, oil, or propane would see payback in relatively short years at recent fuel pricing.

    In my own state of MA there is no subsidy, and only Renewbility's lineup is currently listed on the MA Accepted Plumbing Products list (though others could clearly qualify, or would be allowed on a variance at the local level).

    The US distributor for Renewability is EFI (headquartered in MA), and they're pretty liberal about allowing individuals to open accounts with them, bringing the component cost down substantially from the brick & mortar or direct from manufacturer list-prices on DWHR:

    Natural Resources Canada maintains a tested-performance list to be able to compare apples to apples amongst models & vendors:

    It should be noted that they only work during simultaneous drain & hot-water flows, so tub-bathers aren't going to see a measurable improvement on water heating efficiency with them.

    For hot water gluttons with 6 gushing side-sprays on the showers it's far cheaper than buying multiple commercial tankless HW heaters to handle the sustained flows and cuts the fuel consumption in half. (But nobody reading a green building blog is likely to be building one of those, eh? ;-) )

  2. User avater
    Dana Dorsett | | #2

    There I went and did it, writing a longer response post than the original blog article. :-)

  3. Jin Kazama | | #3

    Hot water gluttons
    "For hot water gluttons with 6 gushing side-sprays on the showers it's far cheaper than buying multiple commercial tankless HW heaters to handle the sustained flows and cuts the fuel consumption in half. (But nobody reading a green building blog is likely to be building one of those, eh? ;-) )"

    You'd be suprised about that ...
    i am pretty found of very long very hot shower,
    and the first floor shower i installed already has 4 outlets, and i regularly use 3 of them simultaneously ( it is my stress relief time .. )
    and my main bathroom ( soon to be done ) will have 6 outlets using Kohler DTV valves....
    but that all brings me to " DAMN do i need to work on my hot water setup "
    right now i am spending more than 1000$ /year on heating water

  4. Jin Kazama | | #4

    did some research a

    did some research a few days ago...
    seems like many chinese manufacturer already provide with split HP water heater working down to -20C or so ..providing COP of 2 to 4 .
    Fujitsu also seems to have a few models and units out in some eastern europe countries
    with higher COP ...

    I inquired with 2 chinese manufacturer that "looked" better than usual chinese products,
    and i was quoted in the 1000-2000$ per kit ( 300liter insulated tank + exterior heat pump and all required parts )

    When are we going to get the goodies ??

  5. User avater
    Dana Dorsett | | #5

    So, Jin...
    ... do you have your drainwater heat recovery system installed yet?

    No matter how you're heating hot water, a DWHR is going to pay off in gusher-showers like that, and if you have a tank, you'll double (or more) the available showering time. (Which is why I set the time-out on the bathroom occupancy sensor light switch to about 10 minutes, otherwise my kid would still be in the shower. :-) )

  6. Jin Kazama | | #6

    Dana: i am a bit shy to
    Dana: i am a bit shy to admit ..

    i have 4 electrical water heater tanks ( 60gals ) installed in pairs
    we will have alot of visit in the future ( family all over the place ) and need to be able to 'serve" many showers /baths in a row and since the standby heat is only wated during summer ..

    i haven't installed a recovery unit yet , i was unaware of the existence of such device a few years ago..
    in fact , i was unaware of many things about "efficiency" and " green building " only a few years ago

    i am still considering what i will do for my house in the near future ..

    may be looking to get a chinese heat pump and remove 2 of the tanks,
    the 2 remaining ones would be feed by a preheated tank run by the HP
    not too sure how this would turn up the efficiency

    the recovery system on drain would be a nice thing to add here for long shower
    i am considering it ..may DIY one ..i'll see how it goes

    my water system is already much complexe, and i still have to figure out how i will be re-using
    my current geo loop and water tank system with solar thermal
    or not use it at all and invest more in PV ...

    the only thing i am sure of, is that i will not make the same mistakes again
    in my future projects ! :)

  7. Jan Juran | | #7

    Hi Dana: When I swapped out all the conventional 2.5 GPM showerheads in my house for Niagara Earth 1.25 GPM models (approx $7 each), I was pleasantly surprised to discover no difference in shower efficacy. The combination of a Niagara 1.25 showerhead plus a Power Pipe would save approx 75% in energy vs. the base case; enough perhaps to allow you to consider raising the occupancy sensor to 11 minutes if desirable?

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