Hot water from vehicle's engine (via heat-exchanger)?

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  • It always seems such a waste to arrive at a parking spot, set things up and put the kettle on, whilst all the time your lovely piping hot water in the engine is cooling down, with all the energy going to waste. Sometimes we'll actually be heating water in the water-heater or on the stove at exactly the same time as there is a cooling system full of lovely hot water. Surely while we're driving along it's not beyond the wit of man to be simultaneously converting engine heat to hot water?
    Therefore I wonder if there is a heat exchanger made, or if anyone can give any tips, benefit of experience etc on making use of that heat to convert it into a few gallons of hot clean (non-anti-freeze!) water for a shower etc? I haven't managed to find anything suitable on Youtube, though maybe I'm not the world's best 'searcher'. Thank you.

    Not a shred of evidence exists in favor of the idea that life is meant to be serious.

  • Boats use them quite often, i think you don't often see them much in camper vans because of the extra weight and cost plus most motor home manufacturers don't seem to want to mess with the base vehicles mechanics to much, warranty issues i suppose.


    Combine one with a diesel cab heater and you'd have a great water heating and back up heating system i reckon, cab heaters cost a fair bit to buy but are cheap to run, obviously not as cheap as a wood burner but pumped hot water would be nice. :D


    Given some extra plumbing and an old radiator or two you could run the engines water round the van to heat it, it should have more than enough spare heat for that if you have the weight capacity going spare.



    This is interesting,


    http://www.canalworld.net/forums/index.php?showtopic=42497

  • how would this work then? could ya just put it on a wood burner and pump water through it to get hot water?


    Calorifiers we are talking about are water/water heat exchangers that use the hot water from your engines cooling system to heat your domestic water supply, your talking about a back boiler. :D





    Actually I shall edit this to say there is no reason you couldn't combine the whole lot into one unit that had multiple heat sources to heat your water so you could choose which to use, would get fairly complicated though and unless you built it yourself would take a lot of time to get the purchase cost back.

  • I've just finished a stove with a back boiler, but that is for running heat to a radiator. It circulates by gravity and works very well. The point about the calorifier is that it uses heat from the engine while you're running, so when you park up you have a tank full of nice hot and clean water, suitable for drinking as well as bathing, and of course free since it uses waste heat from the engine.

  • Been looking at calorifiers on and off all day and they are a bit out of my price range, so I'm going to look into making one. It can't be impossible to take a couple of spurs off the heater matrix and divert off to a little exchanger and a tank. I suppose there is a chance though that unless I'm lucky enough to find the parts at the dump or car breakers it could end up costing the same as a calorifier! I'm always doing that.

    Not a shred of evidence exists in favor of the idea that life is meant to be serious.

  • hi try researching * flat plate heat exchanger *
    they can be got out of old heating boilers so cheap, also on eblat but way more expensive.
    they are added in to the vehicle cooling system & heat the secondary water
    without the 2 mixing, if that makes sense


    good luck

  • Thank you Revel, Julian, Popuptoaster and Madrat.
    Revel, I saw your post and have been reading up about these flat plate jobbies. That sounds exactly what's needed to warm the water up efficiently, even with a relatively short journey.
    I'm thinking 't' pieces off the pipes going to and from the cab-heater matrix and then via a hand operated valve to the plate exchanger, an 'in' pipe and 'out' pipe with small thermostatically-operated 12v pump to send cold in and take heated water out and store it in an insulated container under the bed.
    I think I need to check that the alteration I make won't upset the pump or any of that mysterious - to me anyway - stuff that controls modern engines - it's a '2004 Transit 2.0 turbo diesel. I might be worrying about nothing of course, but it's better to sort it out now than after a problem arises. I need to ensure the plates and other new parts of the system wont be damaged by antifreeze, and that I'm able to easily drain the clean water side of the exchanger should my van be unattended during a bad freeze-up outside. Also it's important to find a good length of tubing to engine coolant water to and from the exchanger. I'd probably use standard red and blue pipe from the exchanger to the storage tank just like the rest of my van's plumbing.
    I'm fairly new to this forum but the help you've given me has been so kind and valuable, thank you ever so much. I hope maybe this helps others here too. Dave.

    Not a shred of evidence exists in favor of the idea that life is meant to be serious.

    The post was edited 1 time, last by Lionheart888 ().

  • I did the same, saw some things on here and went and looked for more info, have also brought things ive seen elsewhere here, im pretty handy with stuff and have an naturally engineering mind i think, so i like all these ideas, storing up a lot of info for my truck when i get it.


    I have a rough rule of thumb for ideas that i mull over in my head, i decided that while I'm not into "glamping" I did want to retain most of my home comforts and i wanted it to be easy to do so even if it was harder to build in the first place.


    My rule of thumb is, if i invited my "normal" mates over would they be able to operate everything in my truck without long, complicated instructions and would they look at me and say "wow this is nice" or would they say "poor bloke having to live like this"


    Not that i care what they think and they know it, but it does help me keep a clear plan in my head when i have stupid ideas. :D

  • So let me get this straight, if i get copper piping similar to brake pipe. The flexi stuff plumbers use?
    Connect one end to one side of the heater matrix, stick a tap into the line. run it to my water tank and have a coil of copper inside it.
    The other end of the copper piping going back to the heater matrix.
    Is it that simple?


    If i wanted to do the same from he burner flue would that work as well?

  • hi lionheart, these fphe (flat plate heat exchanger) are used to warm cooking oil when running diesels on waste oil
    try this link,


    http://www.vegetableoildiesel.co.uk/forum/index.php


    its the best uk based veg oil / biodiesel site
    use the search function with FPHE or flat plate heat exchanger & you will get loads of info
    & an understanding of fitting one,... adapting it for your use of course.
    try including transit & your well on your way


    hope this helps & keep us informed if you try it :)

  • One possible drawback i wondered about - if you're drawing extra heat from your vehicle's cooling system does it mean that your engine would be running colder and would this be enough to affect fuel consumption?

  • One possible drawback i wondered about - if you're drawing extra heat from your vehicle's cooling system does it mean that your engine would be running colder and would this be enough to affect fuel consumption?


    Engines makes masses of extra heat, it could heat several house let alone one van, a diesel engine is only about 35% efficient more than 60% of its fuel energy comes out as heat, turbo engines use some of that exhaust heat to drive the turbine but almost none of the coolants heat is used, its mostly vented to atmosphere via the radiator.


    just make sure the 'stat is working properly and the engine wont circulate water unless its warm enough.

  • So let me get this straight, if i get copper piping similar to brake pipe. The flexi stuff plumbers use?
    Connect one end to one side of the heater matrix, stick a tap into the line. run it to my water tank and have a coil of copper inside it.
    The other end of the copper piping going back to the heater matrix.
    Is it that simple?
    ,
    If i wanted to do the same from he burner flue would that work as well?


    Yup, that's basically it. You could do it with a pipe wound round the flue, but you'd need to put the tank above the heating coil so it would circulate under gravity. You'd have the same problem though that it would only work when you had the burner going and of course you'd be burning wood for the heat. The calorifier does have the advantage of using completely waste heat from the engine and heating up every time you go anywhere.

  • Yup, that's basically it. You could do it with a pipe wound round the flue, but you'd need to put the tank above the heating coil so it would circulate under gravity. You'd have the same problem though that it would only work when you had the burner going and of course you'd be burning wood for the heat. The calorifier does have the advantage of using completely waste heat from the engine and heating up every time you go anywhere.


    So would just wrapping your engine block with the copper piping work? Saves pulling a dashboard apart n messing with the heater matrix plumbing or even just wrapping the copper round the engines water pipes and having the water your heating in the copper pipe?
    Cheers, i know my question is as clear as mud

  • So would just wrapping your engine block with the copper piping work? Saves pulling a dashboard apart n messing with the heater matrix plumbing or even just wrapping the copper round the engines water pipes and having the water your heating in the copper pipe?
    Cheers, i know my question is as clear as mud


    Exhaust would be better, but you would either have to pump it, which is not as bad as it sounds, you can get a small pump that takes only a few watts easily enough, or you have to arrange it so that it circulates by gravity, hot water rising, cold water falling, which might not be that simple...

  • Exhaust would be better, but you would either have to pump it, which is not as bad as it sounds, you can get a small pump that takes only a few watts easily enough, or you have to arrange it so that it circulates by gravity, hot water rising, cold water falling, which might not be that simple...


    Window washer pump from scrappy, direct wired to ignition. Easy peasy piping hot water, cheers julian

  • I seem to remember old BT vans had a small heat exchanger fitted to provide hot water for hand washing. I have fitted a heater matrix in the rear of my old girl with a fan so I can get heat in the rear when engine running , just fed the supply from the cab heater also heats my veggy oil feed to engine via a home made heat exchanger made up of plumbing fittings .

  • one drawback with using the exhaust heat, is the temp of the thing,
    it can get bl**dy hot very quickly, especially when the engine is underload
    so you would need a large volume of water, or some sort of valves/control to keep it safe

  • Wrapping pipe round the exhaust will work (we used to wrap window washer pipe round the top hose to get warm windscreen washers before heated ones were around) but its air/water heat transfer and far less efficient than water/water even before you factor in the pipe only being heated from one side while air cools it from the other.


    It will also probably be as much trouble to install as extra pipes on your cooling system which dont have to be on the heater, although that is convenient because of pipe sizing you could take a feed from anywhere after the thermostat but before the radiator, even diverting the flow into the van, through your calorifier, through a couple of rads and back into the engine bay and the radiator should work although it does mean you can't isolate engine from heating should there be a leak.


    The engines water pump wont care how much water it's pumping so will cope fine as long as your not asking it to pump water up to high and your not restricting the flow with thin tubing.

  • there is a downside to cooling the exhaust it could increase rust in the silencer due to accumulation of damp. as the engine burns hydrocarbons and one of the products is water. exhausts often rust from the inside out.
    not so much of a problem during long runs but may be a problem if you are doing lots of short runs.
    for circulating water i am using one of these, they are not cheap and there are cheaper out there, but i just needed it to be reliable. think i got mine for about 80 though.
    http://www.ebay.co.uk/itm/BOSC…ts_SM&hash=item3f171d1ce8
    if you store the heat and you dont end up using it, it can be reversed and run around the engine to pre heat it (am working on various heating systems on mine).
    if you plan on using the engine coolant through the calorifier without isolating the cooling system with a heat exchanger, it might be a good idea to flush the cooling system out and replace the coolant to make sure you are using a less toxic variety of coolant. just in case the calorifier coil leaks, i know hot water is not often drunk but it should still be protected from toxic fluids.
    http://en.wikipedia.org/wiki/Antifreeze

  • at the manifold yes it is hot, that drops along the exhaust, i'm just saying it might increase condensation by reducing the heat espicially on short journeys. short journeys are know to rust an exhaust quicker due to the exhaust not heating up as much and as heat is being taken out it might increase the heat up time making this worse.
    it dosn't bother me at all though and yes if it did rot it out quicker an ss exhaust would be a good idea, have considered and am considering doing so myself, probably further down the system such as the downpipe though where it is cooler, will probably use ss tube. was thinking of a tight coil so there are no air gaps between the tubes so as to encase the downpipe, also lagging over the tubes on the outside. as a precaution regarding ehaxust gas temperature loss i was going to have a 1 or 2" air gap around the tube so the echanger only collects radient heat and maintains the exhaust gas temp by insulating it to a degree possibly even encouraging the temperature to in crease along the exhaust faster, increasing the exhaust life.