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

5,020W

44C

2.9 Approx

5

4,000W

38C

2.9 Approx

4

3,250W

34C

2.9 Approx

A Victron 5000VA Inverter Charger can operate 30% over capacity for 30 mins , providing the voltage does not drop.

This means that the Multiplus II 48/5000 can operate at setting 6 for up to 30 mins at 25C but as the environment of inverter temperate rises, the rating decreases. For most people the hot shower is 5 mins and this Inverter should operate reliably to meet this temperatiure.

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)

Safiery Tankless Instant Hot Water System

Rated output (240V)

6kW

Rated current (240V)

30Amp

Minimum operating pressure

0.02MPa

Temperature adjustment

Up to 45°C

Tank capacity

None

Mixed water volume at 40°C from single draw off

N/A

Maxim Pressure

0.6MPa

IP Rating

IP24

Height

350mm

Width

230mm

Depth

60mm

Weight (filled with water)

5.3kg

Colour

Black

Temperat

40°C

SKU EHW240206000
Brand Safiery 240V

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