Heating water from the engine

Discussion in 'Tech/Mech General' started by Wildbill, Aug 23, 2016.

  1. Wildbill

    Wildbill Funster

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    My water heater is knakerd so thinking of replacing the gas with a heat exchanger.
    System a coil in the water heater to use the engine heat from the heater system
    Its a bit of tinkering.
    To buy a new heater is nearly 500 plus fitting.
    I have it all apart at the moment so its only a case of making a coiled loop
    And sum tank fitings then plumb in to the system
    Mesuerd the pipe run won't be any more than five letters of extra colent
    Reckoning abut therty min of driving and a tank full of hot water for nothing
    As long as its after the themosstat I suld not affect the working temperature of the engine
    Bill
     
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  2. Muddibootz

    Muddibootz Funster

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    I like the thinking. Be interesting to see how you get on.
     
  3. Flamenca

    Flamenca Funster Life Member

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    I had this system on a boat and it worked efficiently.
     
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  4. pappajohn

    pappajohn Funster Life Member

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    It will need to be on the engine side of the stat or it wont get warm enough in cold weather.
    What you going to do when on site.....run the engine for an hour ?
     
  5. Wildbill

    Wildbill Funster

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    Nothing to lose water heater is scrap any way don't she any reason why it should not work.
    I have research a bit I might use 10mm pipe yet for the coils
    Bill
     
  6. Wildbill

    Wildbill Funster

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    I am going to fit a smaller heater I have from my caravan
    Bill
     
  7. hchris

    hchris Funster

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    You need to control the flow from the engine a friend has done this and it boils the water in the motorhome heater on a long run.
    You need a valve in the feed for the engine that will close when the water heater gets to 60c
     
  8. Wildbill

    Wildbill Funster

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    Whare do you get the as valves
     
  9. John Laidler

    John Laidler Funster

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    Sounds a good idea Bill, I would take the feed from near the outlet of the pump so there is a better chance of good circulation.

    I think you need to fit some sort of safety valve on the hot water tank or perhaps just vent it to atmosphere. The reason is the water from the engine, being pressurised, might be over 100C so the water in the tank could boil. It may never happen but just in case. :)

    Edit: Crossed with @hchris!
     
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  10. Wildbill

    Wildbill Funster

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  11. Wildbill

    Wildbill Funster

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    Will put a thermal valve actuator on the down stream side of the system when the water is coming out at 60 deg the water in the boyiler will be the same give or take a few deg
    a 12v underfloor heating valve will do the job
    Or thermal actuator valve
    Bill
     
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  12. chaser

    chaser Funster

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    Here comes my doom and gloom, it all seems to be a lot of trouble just to get some hot water, and only works if the engine is running , must be better to mend what you have, or get a second hand boiler and have it right, just saying(n):)
     
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  13. Enword

    Enword Funster

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    In the 90s we had an old Merc 407D race van, I made a heat exchanger for the exhaust, just on thermosyphon to a container in the van, worked well but never finished it properly:blusher:
     
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  14. Enword

    Enword Funster

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    Probably no good for cat/particulate filter type jobbies etc, taking to much heat away from the exhaust.
     
  15. Wildbill

    Wildbill Funster

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    Whares your since of adventure man seen this work on boats don't she why it won't work on a MH
    Bill
     
  16. chaser

    chaser Funster

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    Quite agree bill my sort of bodge to a t but when you have got to rely on it in the middle of a winter night you won't want to be getting up to go and warm the engine up.
     
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  17. NickNic

    NickNic Funster Life Member

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    We've got something similar in our van as part of the Alde heating.

    There's a heat exchanger that uses heat from the engine to run the central heating. It doesn't do hot water in ours but the principle has to be the same.
     
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  18. chaser

    chaser Funster

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    My son in law had an rv with a similer system but the tank was in the roof so it all worked on gravity , hot from tHe engine went up and down and the hot water system needed no pump as the shower and taps worked on gravity, but it's still a bit iffy in your case where you are going to rely on it every day, not just a weekend.
     
  19. John Laidler

    John Laidler Funster

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    The Eberspacher heaters are connected to the engine coolant.
     
  20. Wildbill

    Wildbill Funster

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    I won't be taking a shower in the medal of the night and the blown air heating will keep us toste.
    It Hansent worked for three years like I see in the op nothing to lose.
    I will be fitting another gas heater but this will save gas free hot water from the engine when we stop
    Bill
     
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