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Heat exchanger

Thommo

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Oct 16, 2013
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34
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australia
Hi all
was wondering if anyone has fitted a heat exchanger to the heater lines Bon the car for hot showers. As I do mostly beach work it's nice to have a quick fresh rinse off before bed. I am looking at either the inline models, but think they may not produce enough heat, the other is a ss plate type heat exchanger. Has anyone got any info to help me decide?

thanks
 
Andrew fitted a really nice ready to go kit for this. Complete with thermostatic mixing tap. There are pics of it on here somewhere if you look around
 
Looks really good. Now I have three to choose from!
 
I have a Helton heat exchanger from oz ready to fit but can't add much more to the conversation. It's very small in size and they say it produces more than enough heat.

I shall watch with interest.
 
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I love how Andrew's setup has the thermostatic mixer ... so your water will always be around the same temp. Should also make it safer so you never get scalding hot water coming out.
 
The Helton is the inline one I was going for, but couldn't find any data on temp rise at x lpm, hence asking the question. I was also going to fit a thermo mixer, just hadn't seen them in kit form like Andrews. I looked at the price of Andrews and it comes in at 380 pounds, so likely too expensive to get past the wife.
 
Another old thread resurrected, but one still firmly in my mind. I want to put hot water in this truck and have been looking at the best way to do it. I am heading toward the same system as Andrew but had a thought just now. If I removed the rear heater and plumbed the exchanger in there under the seat, could I actually control the water temp simply with the heater control slider? It would eliminate the need for the thermostatic valve. The system would still be pumped from the engine side rather than leave the engine running. But the cold could come straight from the water tank, through the unit and on to the shower or tap. This would negate the need for a cold feed to the valve to mix with the hot from the engine. No? It would make for a very easy installation.

1 engine block pump. I heat exchanger unit. Pipe from water tank. Pipe to appliance. Pick up pump from tank. Cable. Two switches. Cable ties. Hose clips. Screw in hose tails.

Can someone sense check that in the usual fashion?
 
Hi Chris
Sorry to sound thick would you be using the temperature slider to control the temp? If you want hot water in a hot country would you not have to have the heater in the car on then? apart from that it seems like a top idea. also would the heat exchanger be to hot to be under the seat ?
stu
 
I think I would still want the thermostatic mixer ... doesn't really complicate the install too much. Couldn't you just split the cold feed right before the heat exchanger and connect the hot/cold feeds into the mixer on the other side.

On mine the rear heater control is just a switch for low or high ... would that give you enough control? Unless I've missed a slider control in the back for it ... I don't get back there very often.
 
You see that's exactly the sort of reply I needed to make me think. Nothing wrong with the way it comes in the box. But it's more money that could be saved and one less component too. Remember that the heater is two things. Hot water and a fan. If you remove the rear fan unit you still have hot water yes? The fan doesn't push the water round, the engine water pump does. When parked, you run the electric pump. This only circulates water. It doesn't blow out of the heater vents Stu. The temp of the rear heater is linked to the temp of the main heater. You can't split the temp on an 80. It's just a lo and hi fan to blow. When not switched on, there isn't any heat being blown out of the vent under the seat but there is still a small amount of radiant heat there. If I connected the heat exchanger there, then the temp of the water going IN would be controlled by the temp slide on the dash. Would this need the ignition to be on? It might. Or is the temp slider a manual link. But you wouldn't need any of the fans running at all.

If you only wanted cold water from the system, you would turn the slide to zero and get cold from the same tap. Other wise you need a mixed tap and another cold tap. Not saying it's the perfect solution, but it's an idea. The exchanger on its own is £175. Pump is £75 and the rest is pence. Mixer is nearly £60 plus all the other bits and pieces extra that it needs to plumb it.
 
I see no error in your logic Chris, for what that's worth.

The slider on my 80 is 100% mechanical. It's a cable link to a flow regulator on the heater pipe close to the bulkhead.

On the cold slider setting, the flow is restricted (presumably tuned of at the extreme) meaning no hot water would pass through the 'donor' circuit of the heat exchanger.

I would have thought the biggest problem/difficulty would be the unknown volume/rate of flow of cold water that could be heated by an exchanger.

I've done no research whatsoever as to how much water is required for a shower, or what the rate of its flow through a heat exchanger would need to be. These would be the main criteria, IMHO.
 
Heat exchanger ... I bought one of these. I now think (after seeing Andrew's) that this would be too small .. but I'm yet to do any testing. They have much larger ones for prices well below £175


http://www.ebay.co.uk/itm/Stainless...d=100011&prg=1005&rk=1&rkt=5&sd=360635994653&

I also managed to pick up a mixer on ebay for £6. They don't seem to be too hard to find for cheap.

http://www.ebay.co.uk/itm/intamix-1..._Bathroom_Shower_Units_PP&hash=item1c3ac9053b


Your logic for the control does seem very sound though. I wasn't aware that the rear heater temp was controlled by the front.

What pump have you had a look at? I have a couple of shurflo pumps ... but the things are huge!
 
when you have the slider set to hot and your moving you get hot air coming from the vents even if you dont have the heating fan on (front or back doesnt matter) the wind going through the system is enough to push heat about. I do like the idea but would be concerned about having to drive around with the heater on the whole time if you were going to need it. although if you had stopped and then put the electric pump on to get the hot water flowing you would be out of the car. as you wouldnr be storing the hot water you would only have to heat the exchanger up so this wouldnt take very long anyway.

If you stopped and were camping then it wouldnt matter as your not driving but how long does the engine stay warm anyway? (i know it depends where you are) I think the slider is cable operated as it comes through on the bulkhead just on the n/s of the car.

stu
 
Stu, I think you are missing a bit here. At no time would you need to have any hot air being pushed by the car's movement, through the vents. You'd have your air con on nice and cold. Engine would be boiling hot. You park up, move the slider to meduim hot, start the engine pump which would sent water round the heater matrix with no fan on at all anywhere. This heats the heat exchanger. You switch on the submersible pump and hot water pours out of the tap. The only thing you could not do would be run the show AND have the air con on at the same time. But car parked, engine off there is tonnes of hot water for at least an hour or more. In fact Ii think with my idea, more hot water than with the original. With the set up as sold, the water goes from the engine to the exchanger at a fixed temp. Bloody hot. This is actually a waste of heat because you only want it warm. So you have to mix in cold water to cool it at the shower end. If you use the temp slide to control the temp from the engine to the exchanger, then you actually take less heat from the engine, in fact the temp going into the unit would be only marginally more than the water coming out of the tap (there will be some losses). That way, you could actually heat much more water than before.

Clive all of that capacity stuff has been done. One hot engine, switched off, will heat buckets full of water. There is a proven system sitting in a box waiting for delivery - at a cost. I just think that between us, we're cleverer than that and can do this more cheaply and efficiently. Why waste all that engine heat, heating water to more than you need to have to cool it back down again?

You guys do get the principle that there is an additional water pump that pushes the coolant around the block - yes? I didn't get that at first and couldn't see how the exchanger got fed.

Grant, with you on the 'get the same stuff but cheaper elsewhere' Absolutely.

Yes the rear heater is fed from the main heater pipes. This is why corroding rear heater pipes is a big issue. If they go then you loose the whole engine coolant. Pretty sure that the rear heater can only deliver what comes out of the main vents. But not in relation to aircon though.
 
I was getting it toward the end chris. You wouldnt have to heat it up when driving just when stopped! If thats the case i cant see any problems to it.

I got the electric pump to move the water around the system part and when its warm the thermostat will still be open to no worries with a blockage in the system. It would also help cool the engine down after a days driving as you are taking extra heat out of it.
 
I was actually wondering if there was a way to use the system to work in reverse to pre heat the block when it's cold. But it may have to involve boiling the kettle!

What ever the final plan, there are some savings to be made here. OK the clips and stuff are cheap from this guy but there has to be a saving on the mixer valve at very least. The exchanger is though, the neatest that I have seen and is proven tech. I'm tempted to buy the pump, exchanger, tube and hose tails and give it a lash up test with the heater removed. With the exchanger below the engine and the water tank it would always have a head of water and also be easy to drain if required. Question is do I replace my old rear heater pipes with nice new flexi hose right from the start. They look pretty flaky.
 
Here's another video. This time a non pumped system that requires the engine to be running. But if you look at the results they're pretty good. Now you may struggle to understand the guy as he has some weird and unusual foreign accent.

 
good video cant place the accent though!
you can buy a pre heater for a merc sprinter for about £40 which if you plumped that in as well would work as a block heater and can be set up with a timer. 12v and diesel powered.
looked at the ebay link above and how do you know what kw output you would need?

stu
 
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