My current Surburban Electric Only HWS is approaching end of life, why because the majority of our time is spent where our water is bore water for general use and Rainwater for drinking. Regular maintaince annodes swaps and decalcification occurs, most recent inspection and service show flaking rusty metal amongst the Calcium.

I am considering an electric instant HWS as a replacement in leiu of a new Surbarban Elec HWS. I have no desire for anything that requires gas for which there is no benefit as we always use powered sites at CP's and never free camp anymore.

Has anyone any advice on such units.

We have two Hocking instantaneous HWS. 22kW each. 3 phase. In summer we turn off 1 phase as 2 phases are hot enough (switch is on the side).

Hocking it now Wilson Hot Water.

Still got an old Dux ihws in our building in the common laundry, but it is being replaced soon due to old age, rust.

HUGE difference between a storage electric hot water system and an instantaneuos electric hot water system.

Note Whenarewethere's comments that his systems are 22 kw, 3 phase.

For a typical caravan park power outlet rated at 15 amp, you'll be limited to a 3500 watt electric instant tankless hot water heater which will literally give you a trickle of hot water (38 degrees Celsius) during winter.

I have a 18 litre per minute, instantaneuos gas hot water system which gives me a very strong shower up to 48 degrees Celsius for which I buy a Swap 'N Go bottle every 4 months for $32.00 (much cheaper for refills at BCF).

If you want a strong and hot shower then an electric storage system (minimum 30 litres for 2 people) or an instantaneuos gas system are the only practical options.

A final comment: do you know any, ANY caravan manufacturer that uses an instantaneuos electric hot water system to supply hot water to a shower?

Here is the Stiebel Eltron IHWS, 3 power ratings, but even the small one is drawing 20 amps per phase.

Thinking more about the corrosion issue:

Not to forget that IHWS have about a half litre tank which the 3 heating elements sit inside. These are still going to corrode with highly mineralised water.

Probably what you need is a 'hard water' filter. Often used in Germany as the water is extremely mineralised. They have a large filter in the basement for the whole house. It needs to be a filter for hard water, not just a drinking water filter.

Check out the Dometic (Atwood) tank HWS systems. No anode required as tank is aluminum. Gas & 240V.

Have not heard of a tankless 240V HWS for caravans. Only gas.

Mein wrote:

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For a typical caravan park power outlet rated at 15 amp, you'll be limited to a 3500 watt electric instant tankless hot water heater ......

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 And don't forget to ensure that no other electric appliances are running at the same time. Often a caravan park 15 amp supply will provide more than 15 amps but you risk overloading the plugs, sockets and cables.

Last trip I had to replace the van inlet socket and lead because the 15 amp extension lead had welded itself to the van inlet. After cutting off the socket from the extension lead so we could drive off, there was no way to get it apart without destoying the van outlet.

Thinking back, we had been running too many appliances. They all cycle on and off but if by chance they all cycled on at the same time it would have been :

• water heater (1440 watts)

• stove element (800 watts)

• fridge (325 watts)

• air conditioner (1500 - 1600 watts)

• battery charger (300 watts).

That is well over 4000 watts or 18 amps. I was still surprised that was enough to weld the contacts together. Perhaps the 1100 watt microwave had been used at the same time but I doubt it. There is also the kettle and coffee frother but I check what is running before switching them on.

At other times we have definitely run the microwave at the same time as the stove element without thinking much about it.  If the water heater and fridge cycled on then, that would be just over the 15 amp limit.