While we were building our washroom on the plot, we were thinking of having a hot water shower in there as well. But instead of having a boiler and keeping the water hot for an extended unused time, we were thinking of sth different:
A manual boiler and a 12V camping shower.
The ingredients
- 1* 20l wide neck canister Standard-WHK DIN 96-20 (or multiple if you like)
- 1* immersion heater with a power rating to your liking, such as “Rommelsbacher TS2003” (with 2000W with AC).
You can also go for a DC model that can be run directly from a (12VC) battery or DC source. Just make sure, that the heater is not longer than the height of the canister. - 1* thermometer, such as “TFA Butter Quark Cheese Thermometer“
I opted to an analogue one going up to 100°C and made from glas instead of plastic. - 1* USB-C power bank with PD and 12V @ 3A
- 1* USB-C decoy/trigger board with terminal
- 1* Brunner AquaFresh 2.0
- 1* short USB-C to USB-C cable for transmitting at least 36W
- 30cm of 1.5mm2 some cable
- 1* plastic bag or similar to fit the power bank and the trigger board
- some plastic tape to “seal” the plastic bag
- an energy source
How it works
- Fill the canister with water (20l max).
- Place the thermometer into the canister.
- Place the heater into the canister and hook it to the opening of the canister. Make sure the metal of the heater does not touch the plastic or the thermometer.
- Power on the heater (either from your battery or your inverter) and wait until the water gets to the destination temperature. For the actual duration see “The maths” section below.
- Remove the heater.
- Insert the immersion pump of the shower into the canister.
- Connect the power bank to the USB-C trigger board via the USB-C cable.
- Have the trigger board output voltage to be set to 12V permanently or set it manually to 12V.
- Connect the power calbes of the shower to the trigger board.
- Have a shower.
The maths
In case you are wondering, how it would take to heat up the water, here is my calculation (with the formula taken from various sources on the internet).
Q = m * C * delta(T)
So in case we want to heat 20l to 43°C from an initial temperature of 15°C with a 2000W immersion heater, we might need to wait for approx. 25min. If we did same but with an initial water temperature, it took us roughly 33min.
With a 1000W immersion heater, the numbers would change to 49min and 66min. And with a 400W we would have to wait 122min or 166min.
The amount of power needed is also shown on the above table. As you can see, it uses between 650Wh and 885Wh. So be careful when using a 12V immersion heater with your 90Ah car battery – don’t …
Conclusion
It quickly becomes obvious that a heater with only 400W will take too long to heat the water. At least I would put it over night into the motorhome, caravan, trailer or wahtever place so it can “pre-warm” a little bit. This might save you between 45min – 60min.
With 20l of water the shower experience will be limited to under 6min on “full throttle”. But with careful “breaks”, I still think the amount of water is sufficient for a full shower (not including washing long hair, of course). And if this does not provide sufficient water, there is always the option to add another 20l.
And: we will post a video with visual evidence as soon as it gets warmer …
Our Journey to Scotland 