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Heat exchanger

No I don't think so. That wouldn't really work. I'll say again, the water does not need to be hotter. If the engine is 80 and the water out of the tap is 60 then there is loss of course. But if the engine has cooled to 40 passing it round twice won't make it any more than 40. Well that would still be hot enough, but when the engine is 20 - it's colder than tap water from the mains. And what I am saying is that if you fancied a shower in the evening long after pulling over, the engine is cold. You can't create heat energy from nothing.

The piping involved would be significant. too. I'd have to circulate the water without drawing any off. That doesn't work. Not without having a storage tank. Nope too complicated. In answer to Tim, I do not have any trouble at all getting heat to the exchanger. It's scorching. The electric pump is circulating water from the engine through the unit. Cold is then drawn over the element and comes out of the tap. If I stop the tap momentarily then open it again, after a few seconds the water that has paused in the HE comes out and it's nearly boiling. So the exchange process works a treat. But what I am saying is that the engine cools so quickly that its no longer hot. Passing that round a dozen times won't make any difference. A cold engine is a cold engine. The engine is a massive thermal lump and radiates heat in all directions. Look at how long it takes to heat up in the first place. The idea is to have a hot and cold feed. You set the output temp by adding cold water to the hot. But as the temp is perfect for everything at its hottest, there will never be the need to add cold. So that's why I don't have it set up as Tim probably suggests.

It's not a case as he suggests that the engine is hot but it's not sending hot water to the exchanger, that's what the pump is for but once the engine cools and the thermostat shuts there is limited circulation. Leave the engine running and you can have hot water all day. But that's not what I wanted. If there wasn't a thermostat in there it might make a difference. What I don't know is, when the stat is shut, how much circulation of water is there around the block? Does it sit there like a jacket gradually warming up with the water pump just spinning, or does it move. If the water doesn't circulate until the stat opens then it's never going to work for that long. once you switch the engine off. And that may be the issue. My rad is very effective. I had it custom cored. When the engine is off and the electric pump is running, it pushes water around the engine including the radiator. So how long is the engine going to stay hot with an aux cooling system running. See the point? I bet if I could bypass the rad it wouldn't cool nearly so fast.
 
No I don't think so. That wouldn't really work. I'll say again, the water does not need to be hotter. If the engine is 80 and the water out of the tap is 60 then there is loss of course. But if the engine has cooled to 40 passing it round twice won't make it any more than 40. Well that would still be hot enough, but when the engine is 20 - it's colder than tap water from the mains. And what I am saying is that if you fancied a shower in the evening long after pulling over, the engine is cold. You can't create heat energy from nothing.

The piping involved would be significant. too. I'd have to circulate the water without drawing any off. That doesn't work. Not without having a storage tank. Nope too complicated. In answer to Tim, I do not have any trouble at all getting heat to the exchanger. It's scorching. The electric pump is circulating water from the engine through the unit. Cold is then drawn over the element and comes out of the tap. If I stop the tap momentarily then open it again, after a few seconds the water that has paused in the HE comes out and it's nearly boiling. So the exchange process works a treat. But what I am saying is that the engine cools so quickly that its no longer hot. Passing that round a dozen times won't make any difference. A cold engine is a cold engine. The engine is a massive thermal lump and radiates heat in all directions. Look at how long it takes to heat up in the first place. The idea is to have a hot and cold feed. You set the output temp by adding cold water to the hot. But as the temp is perfect for everything at its hottest, there will never be the need to add cold. So that's why I don't have it set up as Tim probably suggests.

It's not a case as he suggests that the engine is hot but it's not sending hot water to the exchanger, that's what the pump is for but once the engine cools and the thermostat shuts there is limited circulation. Leave the engine running and you can have hot water all day. But that's not what I wanted. If there wasn't a thermostat in there it might make a difference. What I don't know is, when the stat is shut, how much circulation of water is there around the block? Does it sit there like a jacket gradually warming up with the water pump just spinning, or does it move. If the water doesn't circulate until the stat opens then it's never going to work for that long. once you switch the engine off. And that may be the issue. My rad is very effective. I had it custom cored. When the engine is off and the electric pump is running, it pushes water around the engine including the radiator. So how long is the engine going to stay hot with an aux cooling system running. See the point? I bet if I could bypass the rad it wouldn't cool nearly so fast.

Chris - not going to reply in full except to say yes that all was understood when I wrote my original response - it is for the case where the losses are significant in relation to the heat that is there (say 60C block temp/40C out case....clearly it is impossible to magic up heat gain in this system...which is not what I was suggesting). Also if the tanked/stream fed water were particularly cold then the conversion loss would be higher...thus going round a system twice would overcome that (if your engine were hot enough in the first place). Given that you don't run your engine whilst showering then the issue is that there is only so much heat store there....a matter of physics). The problem with a non-running engine approach is that there is no more heat being generated and the nice cold water is sucking all the heat out of it. I suppose that is the compromise for peace and quiet.

PS - if you use only onboard water sources and don't have a water-sucking/sand spear approach then I agree recirculation would be more difficult....otherwise there is no additional kit other than use of a bucket

PPS - when the jacket water temp drops then the engine thermostat should operate taking the radiator out of circuit...unless the stat is not working/removed. On my 100 this occurs at 82C...not sure on an 80
 
Cheers Steve. Yes, what's disappointing is that in the video, the car has been parked for some time and they get a lovely shower. If I come to mine an hour after parking up, the engine has cooled so much that it would be tepid at best. I don't mean the water coming from the unit, I mean the actual engine. The 80 really doesn't seem to suffer from over heating more's the pity almost. It's a cool running thing. I did think about running the water back into the tank and back around, I could do that as it's not really drinking water, but in terms of water quality, warming it up and cooling it constantly isn't a very good idea, especially for showering. Not good for bacterial growth. Well actually exceedingly GOOD for bacterial growth. From cold, and not driving, I could run mine for 20 mins and it wouldn't be hot. They reckon for a car engine, from cold, you only need something like 2 mins. Hmm, not a chance. I love my Kampa hot water Geyser, it's brilliant, but it takes up a big space. If I went to 2 seats only, I'd build that in.
 
I've solved the cold-hot engine problem with a wet webasto. Whenever I want to shower just turn the Webasto on and within 5 -6 minutes I get hot water.With the Bushranger HE I get atleast 45-47C degrees water which is a bit more than I like. So I started today experimenting building few different size HE out of aluminum ( got a pile of material).And I'll see which one I'm gonna like and keep under the hood:)
 

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