Exhaust heat exchangers...

Discussion in 'Boat Design' started by Mick@itc, Jun 11, 2012.

  1. Mick@itc
    Joined: Jan 2011
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    Mick@itc Junior Member

    Hi all
    I have done a search on heat exchangers here and can't find the answer to this question. Do any boats use exhaust gasses in a heat exchanger for hot water? From what I read it seems to be engine cooling fluid that is used in the heat exchangers??
  2. philSweet
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    philSweet Senior Member

  3. SheetWise
    Joined: Jul 2004
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    SheetWise All Beach -- No Water.

  4. Mick@itc
    Joined: Jan 2011
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    Location: Melbourne

    Mick@itc Junior Member

    Yes, that's what I thought might be the case but no harm in finding out if we had some genius on the board who figured it out for smaller boats with dry stack exhaust.
  5. CDK
    Joined: Aug 2007
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    CDK retired engineer

    For hot water you need a boiler containing the amount of water you want to have available. The heat exchanger normally is part of the boiler. Should you use exhaust gas, there must be a provision to prevent overheating, like a thermostat that diverts the gas flow when the desired temperature has been reached.
  6. Stillbuilding
    Joined: Dec 2008
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    Stillbuilding Junior Member

    I have seen a watermaker which used the exhaust heat. Was designed for a bigger cruiser but it was not very bulky and I thought seriously about for my space but decided that my Perkins 135hp prob a bit small for utility.
  7. Frosty

    Frosty Previous Member

    Dry Exhaust will be much hotter than the coolant. If you looking forward to a hot shower after dropping the anchor either will do, but if you are expecting to draw considerable amount then you need a professional set up from the coolant.

    No restriction to the exhaust should tolerated.

    A leak from your tank to your exhaust could be catastrophic for the engine.

    Ide stick to a conventional water/ water.

  8. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    I almost tried this once...I wrapped a length of small copper tubing around my stack with the intention of running fresh water through it and storing that in a tank for my shower. I didn't get around to finishing up the plumbing when the fishing season started so I left the tubing in place. A couple of weeks later I had to go back into the exhaust for some reason, and when I removed the copper tubing it came out in pieces. I should mention that this was a gas engine so the exhaust temps were pretty high. It didn't take long to realize that with that much heat the water would be turning to steam at an incredible rate...pumps would have to run non stop in order to circulate the water, and pressure relief systems would be a critical component in order to prevent a catastrophic failure.

    I abandon that idea and eventually made my own water heater using engine coolant as a heat source...cheaper, easier and much safer.

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