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Drain water heat recovery

Weezbo Member Posts: 6,232
you definitely need to see M.E. he single handedly has gone where no man has thunk of going before:) maybe some one here still has the thread...


  • Reinvent
    Reinvent Member Posts: 43

    Has anyone ever installed a drain water heat recovery (DHR) unit. Curuios as to their perfofmance in the real world, how can you calc the downsizing of a water heater (or if you should) and how easy/hard are they to install/ retrofit.
  • jerry scharf_2
    jerry scharf_2 Member Posts: 414
    installed but not in service

    I have it in the system. It's not an ideal setup for the device (not all drains covered, only used to preheat the hot water tank input,) but it will be instrumented.

    No one is living there and there is no instrumentation for it yet. ring back in about 4 months. I think I'll follow ME's lead on the title.

    I'm not sure how long the payback is on the unit in terms of heat saved, but I think this is really the future for those showers that have 17 body jets. If it recovers even 50% of the heat, it would easily be cheaper than doubling the hot water capacity of the house.

    Too bad it can't help with filling the big soaking tubs.

  • Cliff Brady
    Cliff Brady Member Posts: 149
    I installed one

    and it works great. I haven't done actual measurements, but when a shower is draining I can feel the outcoming water is much warmer the water going into the exchanger. I have a large GFX Technology G4-60 so it does pretty well even with pulsed load of the dishwasher. Soon I will plumb the preheated water to the cold side of the 2nd floor bathroom and shower as I am cutting into those pipes for my new basment powder room. I also have the preheated water piped to the cold side of the mixing valve at of the water heater which reduces the amount of water that actually has to go through the water heater, perhaps extending its life.

    I have a 40 gallon indirect and a Peerless Pinnacle 140 condensing modulating boiler and have never run out of hot water with aquastat at 130 and boiler DHW supply at 165 degrees. I can start a load of hot laundry (130 degrees), run the dishwasher (130 degrees) and have the family take consectutive showers (119degrees)without running out of hot water.

    The only problem is the price has gone up at least 50 percent since I bought it during a special they were having about two years ago.

    If you anticipate a lot of shower load, I say go for it. The GfXTechnology.com has a lot of studies and charts you could plug your numbers into to estimate a payback.

    I wish more mechanical companies and architects would consider GFX for their projects, especially where multiple units share a stack that also happens be in the vicinity of the water heater.
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