Hot Water System Choices for 4WD and RV

Hot water is one of the greatest uses of energy for the traveller.

Gas hot water systems have several problems:

  • Operate at around 40% efficiency and are relatively costly to run.
  • Are vulnerable to dust ingress into burners rendering them unreliable.
  • Are bulky & heavy when the weight of the gas bottle and mandatory tank is included.
  • LPG is a highly flammable and dangerous energy source.
  • Require venting as they consume oxygen and emit dangerous Carbon gasses.

Electric Hot Water system have several advantages:

  • Electric power can be generated by solar or alternator or both and are inexpensive to run.
  • Are sealed units unaffected by dust
  • Are lightweight and compact in either tankless or tank versions
  • Are protected by circuit protection creating a perfectly safe syste.
  • Do not require venting.

Tankless Electric Hot Water

These are commonly called “Instant Hotwater” and are compact and most efficient. However, to heat water passing through at “speed” requires a lot of power. So they require a high amount of power but use the least amount of energy as they are only “on” for a short period of time.

To achieve 55C from cold 15C water requires 6,000-7,000W of power. As the water source gets colder, the power required rises.

This is too much for even 6,000W Inverters so a different customised solution was needed for the RV market.

Our solution is an instant hot water that is NOT temperature controlled but fixed based on power required. This means the temperature may change according to water source temperature and flow rate.

We have customised the starting power rate to be set on setting "6" on a 2-9 scale which corresponds to 4,850W.

The Victron 5,000VA Inverter charger will sustain this for the 3-4 mins of showering time.

Instant Hot Water (Tankless) Tested Results in Coomera on a cold winters day with water at 15C to start:

Hot Water
Control Setting

Power Used

Temperature

Flow rate
Litres/min

6

4,850W

44C

2.9

A comfortable shower temp is 40-42C.

For a 5 minute shower, 10-12 L of water is used and 218Wh or 17Ah (12V)of energy.

 

 

(EHW240206000)

Stiebel 10L Tank Hot Water System

Rated output (240V)

2kW

Rated current (240V)

10Amp

Permissible operating pressure

500kPa

Temperature adjustment

Up to 85°C

Tank capacity

10 Litres

Mixed water volume at 40°C from single draw off

19 Litres

Standby energy consumption / 24 hours at 65°C

0.32kWh

IP Rating

IP24

Height

503mm

Width

295mm

Depth

275mm

Weight (filled with water)

15kg

Colour

White

ECO setting

60°C

SKU EHW240206000
Brand Safiery 240V

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