Heating stored water

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Davey Boy

Davey Boy

Well-known member
Joined
Dec 11, 2015
Messages
960
I need some advice for a project I'm interested in doing to provide heated water for showering and general washing use on longer trips between washing facilities.
Picture this........
A tank of water say 25litres, a 12v 300w element fitted through the sidewall, drawing approx 25amps (I'm told this by the engineer supplying the heating element) to heat that quantity for showering purposes.
Forget pumps, relief valves, thermostats, fuses etc. That's Included in the design....
My question is regarding the second battery (120amp).
Whilst driving I think I can heat the water, as the alternator is powering the element. But is this ampage starving my battery recharge and affecting the running of the fridge etc.
When I'm parked up, I'd like to switch to solar/battery to to keep the heat for showering, but also heat the water for a while in the morning, for washing or a shower etc.
My concern is this large ampage draw.
Any thoughts.......Rick??:thumbs
 
I've seen this subject discussed think it was on Facebook. The guy wanted to wrap pipe around the turbo. Apparently it's been a few times on the green ovals.

Also would drawing so much current along with fridge and dual charging put too much stress on the alternator
 
I think there are a lot of issues here not mentioned, first is the need to carry 25 Lts water around on a long journey, next is it will need to be very well insulated as 300 watts is not a lot once the temperature rises to shower temp, next is cable size, for the run from battery to tank in van, 4mm sq would be the minimum I would use, otherwise your 300 watts will drop off alarmingly due to voltage loss, next 25 amps from your alternator is not too bad, day time running but take into account everything else you are likely to use, fridge/charging van bat/heater blower/aircon/etc and night running may well put you over the top with lights etc, just some points to check over Rick
 
Davey Boy said:
I need some advice for a project I'm interested in doing to provide heated water for showering and general washing use on longer trips between washing facilities.
Picture this........
A tank of water say 25litres, a 12v 300w element fitted through the sidewall, drawing approx 25amps (I'm told this by the engineer supplying the heating element) to heat that quantity for showering purposes.
Forget pumps, relief valves, thermostats, fuses etc. That's Included in the design....
My question is regarding the second battery (120amp).
Whilst driving I think I can heat the water, as the alternator is powering the element. But is this ampage starving my battery recharge and affecting the running of the fridge etc.
When I'm parked up, I'd like to switch to solar/battery to to keep the heat for showering, but also heat the water for a while in the morning, for washing or a shower etc.
My concern is this large ampage draw.
Any thoughts.......Rick??:thumbs
Click to expand...

The biggest problem is the T2 does not have a very big alternator to start with. It's only 70amp, and that is brand new, and running at the right revs.

Take one that is 15 years old, or so, it could be down at around 60amps or less.

You might be OK on a nice day belting up the motorway, but have a bad overcast day, where you need head lights, demister fan, and windscreen wipers, while you are driving round the back lanes of Wales, the alternator would be struggling to keep the battery charged normally, let alone with any additional loads.

Just to give you an idea, when you start the car, and it starts first time, it takes about 1/2 hour for the alternator to replace what was used from the battery, with out any extra things running on the car, add in bad weather, and the chances are, it won't actually top the battery back up at all, so add your water heater, and you will actually be running the battery flat while driving.

These are rough values, as many things can affect them, making them higher or lower, but it's a guide.

I have been told the ECU uses 15amp
Dipped Head lights, and all the associated lights that come on with them, at least 10amp.
Wiper motor, up to 10amp.
Heater motor, up to 12amp.
Radio, about 3amp.
Turn the Aircon on to help demist, and the radiator fan, plus the electric clutch on the pump, and there goes another 15amp.

That's 65amp

Add things like heated seats, or the Glow plugs coming in, and you are well into the red.

Oh, and you mention a Fridge, that could well be another 10amp!

Looks like you need an Elgrand alternator!!!
 
The Alde heating system used can a heat exchanger so no electric needed.
Maybe worth a look at
 
Lazy-Ferret said:
The biggest problem is the T2 does not have a very big alternator to start with. It's only 70amp, and that is brand new, and running at the right revs.

Take one that is 15 years old, or so, it could be down at around 60amps or less.

You might be OK on a nice day belting up the motorway, but have a bad overcast day, where you need head lights, demister fan, and windscreen wipers, while you are driving round the back lanes of Wales, the alternator would be struggling to keep the battery charged normally, let alone with any additional loads.

Just to give you an idea, when you start the car, and it starts first time, it takes about 1/2 hour for the alternator to replace what was used from the battery, with out any extra things running on the car, add in bad weather, and the chances are, it won't actually top the battery back up at all, so add your water heater, and you will actually be running the battery flat while driving.

These are rough values, as many things can affect them, making them higher or lower, but it's a guide.

I have been told the ECU uses 15amp
Dipped Head lights, and all the associated lights that come on with them, at least 10amp.
Wiper motor, up to 10amp.
Heater motor, up to 12amp.
Radio, about 3amp.
Turn the Aircon on to help demist, and the radiator fan, plus the electric clutch on the pump, and there goes another 15amp.

That's 65amp

Add things like heated seats, or the Glow plugs coming in, and you are well into the red.

Oh, and you mention a Fridge, that could well be another 10amp!

Looks like you need an Elgrand alternator!!!
Click to expand...

Trol 3.0 has a 90 amp alternator ;) still a fair point though.

Davey, I believe the 130 amp one from a 3.0 Nissan Cabstar fits.
 
solarman216 said:
I think there are a lot of issues here not mentioned, first is the need to carry 25 Lts water around on a long journey, next is it will need to be very well insulated as 300 watts is not a lot once the temperature rises to shower temp, next is cable size, for the run from battery to tank in van, 4mm sq would be the minimum I would use, otherwise your 300 watts will drop off alarmingly due to voltage loss, next 25 amps from your alternator is not too bad, day time running but take into account everything else you are likely to use, fridge/charging van bat/heater blower/aircon/etc and night running may well put you over the top with lights etc, just some points to check over Rick
Click to expand...

Thanks for the replies.
This idea is specifically for a France, Spain, Morrocco trip next year.
The alternator is a 120amp upgrade on an intelligent split charge, and I take your point regarding cable sizing Rick.
The system would only need to work when we are about 1.5 hrs out from camp to pre heat this water.
I agree, the tank insulation is crucial to making this work properly. I'm hoping if I can get this right and the heat in the evenings water can carry over to the morning, to some degree at least
I'm thinking of a 100w solar panel installation for when the vehicle is static.
Hoping that 100w is sufficient for this boost on the already heated water.
Still researching the ampage output on various panels at the moment.
Just ideas.....
Thanks again everyone!
 
Just seen your post regarding the alternator.
Thanks for that Barrbeast. :thumb2
 
This thread has got my appetite wet to get the alternator mod done on mine that's been in my signature under the upcoming part for too long now :doh
 
Other options, I can think of...

A calorifier like on a boat, divert rad water through the calorifier, free hot water stored when you need it. Need some control to make sure you keep a good temperature and avoid overheating.

On our boat we have a gas powered Paloma instantaneous water heater, for the shower, diaphragm pump. BUT now you are adding gas to the vehicle.
There is probably a diesel version.

Paint the roof matt black and solar heat the shower only shower on sunny days though...

Heat a few gallons of water on the stove, add it too a header tank and place on roof and have a gravity shower. Or get one of those black bin liner type shower bags, as used on yachts or caravans place on roof, when parked up, shower as it warms up,

Man up and have cold showers every day.... forget that one lol... Gone past that lol...

Calorifier would be my choice, I wonder if there was room under the truck
for a slim one? I think a water tank could be fitted too. Just go under the truck and see how much space is available between chassis rails etc.

Edit... add an immersion heater, and seek out electric hook up on your travels .
Rustic
 
How about a heat exchanger like I'm running to warm my veg? Just pump water through rather than veg, use a small 12v pump and some fancy pipework :nenau

Only downside there is the car would need to be up to temp which may not be great if you want to wash first thing in the morn but you've only got to let it get to temp by leaving it to sit there running for a while.
 
Banshee said:
How about a heat exchanger like I'm running to warm my veg? Just pump water through rather than veg, use a small 12v pump and some fancy pipework :nenau

Only downside there is the car would need to be up to temp which may not be great if you want to wash first thing in the morn but you've only got to let it get to temp by leaving it to sit there running for a while.
Click to expand...

My mate, who's working with me on this project has spoken to the guy that sells the 300tdi shower setup, and he's now re configured it to run direct from the exchanger. He reckons 15mins on tick over to shower hot water. That's a Land Rover, so a Patrol should cut that time in half.:lol
 
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