How many people will need a warm shower each day? This is one of the most important questions to ask when choosing between caravan hot water systems for your adventure vehicle. If you have multiple users on board or need a longer shower, a higher-capacity option like the Aqueous MK2 Water Heater is ideal for both convenience and efficiency.
This hot water system features a 10-litre storage tank and a variable thermostat adjustable from 30Β°C to 75Β°C. As a result, it can provide up to 30 litres of warm water for showering β more than 10 litres extra compared to the 6-litre Aqueous models.
In this guide, we will review the MK2 to help you understand what to expect if you're considering it for your campervan, caravan, RV, or boat. We'll mostly focus on the design, energy requirements, heating time, and other key aspects.
Aqueous MK2 (10L 240V) Storage Water Heater: Specs at a Glance
| Aqueous MK2 (10L 240V) Storage Water Heater | |
| Type of water heater | Point of use |
| Dimensions | 409 x 267 x 262 mm |
| Net weight (empty) | 7.4 kilos |
| Power requirements | 240V AC (4.2 amps) |
| Power consumption | 1000 Watts |
| Water storage capacity | YES (10 litres) |
| Water storage pressure | 0.85 MPa |
| Water heating element | 1 kW |
| Water heating control | 30Β°C - 75Β°C |
| Protective safeguards | Protected against over-temperature, over-pressure, corrosion, and others |
| Warranty support | 12 months |
The Aqueous MK2 Storage Water Heater is an excellent choice if you need a higher-capacity storage water heater for your caravan, campervan, RV, or boat. Its 10-litre tank can deliver over 30 litres of warm water β enough for multiple warm showers and perhaps washing dishes.
This heater boasts a modern, sleek design with an intuitive control knob for setting your preferred temperature. The thermostat allows adjustment from 30Β°C to 75Β°C. And thanks to its premium nickel-based superalloy heating element, it reaches the set temperature quickly.
As a 240V system, the heating element operates at its full 1 kW (1000 watts) rating. This enables rapid heating β typically 12β38 minutes, depending on the incoming water temperature and your desired setting.
For detailed calculations on energy use and exact heating times at different temperatures, continue reading the full review below.
What Comes with the Aqueous MK2 Water Heater?
When you unbox this storage water heater for the first time, it arrives with the essential components needed to get started. These include:
- The water heater: The storage water heater unit itself, complete with an integrated 240V power plug, hot water outlet, cold water inlet, and pre-drilled mounting holes.
- Pressure relief valve: A safety fixture designed to release excess internal pressure from the water storage tank.
- Printed user guide: A detailed leaflet containing specifications and instructions for installation and operation.
- Installation components: Additional parts for securing the unit, including a mounting bracket, bolts, washers, and the pressure relief valve.
Please note: You will need to supply other components and tools required for installation, such as hoses, adapter fittings, a thermostatic mixer (or mixing taps), and a water pump.
How Big Is a 10-Litre Storage Water Heater?
For a campervan or caravan accessory, the MK2 is relatively large. However, it remains compact at 40.9 Γ 26.7 Γ 26.9 cm, allowing you to fit it neatly under a kitchen sink.
The unit weighs just 7.4 kg when empty, but once filled with water, it reaches 17.4 kg (10 litres of water weighs approximately 10 kg). You should therefore mount it in a location capable of supporting at least 40 kg to provide an adequate safety margin.
If you choose to install it in plain sight, this hot water system has an attractive, modern appearance. The housing comes in a white finish with gold accents and a stylish dial for adjusting water temperature.
How Well Is It Built for Australian Conditions?
The MK2 is manufactured in Australia for adventure vehicles, specifically engineered to withstand Australia's harsh conditions, ensuring excellent performance and longevity.
For one, the sleek exterior is made from high-impact ABS plastic, a material highly resistant to cracking and shattering β essential in vibration-heavy environments.
Inside the unit, the tank is constructed from single-line cold-welded steel, coated with a proprietary Blue Diamond enamel, and protected by a magnesium anode rod. This combination effectively prevents leaks, rust, and corrosion.
The tank is also insulated with high-density polyurethane foam, which minimises condensation and air infiltration, providing additional protection against rust and corrosion.
Moreover, the heating element is made from a superior nickel-based Incoloy superalloy, which offers greater thermal conductivity, corrosion resistance, and durability compared to traditional copper elements.
What Power Supply Does It Need?
The MK2 is an AC-powered unit rated for 240V at 50 Hz. This high-voltage design allows the 1000W heating element to operate at full capacity, heating water quickly.
However, the high voltage rating means the unit cannot be connected directly to a 12V battery bank and requires a power inverter. If the inverter is dedicated to this water heater, it should be rated at least 1500 W to provide a sufficient safety margin for the continuous high load.
How Difficult Is Installation?
Like our other point-of-use Aqueous water heaters, the MK2 is designed with DIY enthusiasts in mind. However, it is moderately difficult to install due to the required plumbing and electrical wiring.
The electrical connection must be properly earthed, and a pressure relief valve correctly fitted to the unit. For this reason, we strongly recommend having a qualified professional perform the installation. Otherwise, any damage caused by incorrect installation will void the included warranty, and you'll have to bear the repair costs.
How Easy Is It to Use Day to Day?
The Aqueous MK2 Water Heater is extremely straightforward to operate. It features a user-friendly design with a simple toggle switch for turning the unit on or off and a modern knob for adjusting the thermostat temperature.
Next to the temperature dial are two LED indicators β green and red β that show when the unit is powered on and actively heating. You simply turn the dial to the desired temperature and wait a few minutes for the water to heat up.
How Long Does It Take to Heat 10 Litres of Water?
The MK2 is equipped with a high-precision thermostat offering a variable temperature range of 30β75Β°C. Since it operates on a high-current 240V supply, the 1000-watt heating element runs at full capacity, enabling rapid water heating. However, the actual heating time depends on the selected thermostat temperature and the incoming water temperature.
Using the heater's specifications, we can calculate the energy required to heat the water and the time needed to reach the desired temperature.
Calculating the Energy Required
The energy required (Q) can be calculated using the formula:
Q = mass (m) Γ specific heat capacity of water (c) Γ temperature rise (ΞT)
The MK2 has a 10-litre storage tank, so the mass of water is 10 kg. Then, the specific heat capacity of water is 4184 J/kgΒ°C.
Therefore, to heat 10 kg of water from 10Β°C to 75Β°C (ΞT = 65Β°C):
Q = 10 kg Γ 4184 J/kgΒ°C Γ 65Β°C = 2,719,600 joules
Thus, heating 10 litres of water from 10Β°C to 75Β°C requires 2,719,600 joules (approximately 755.44 Wh).
Calculating the Heating Time Required
Heating time (t) can be calculated as:
t = Energy required (Q) Γ· heating element power (P)
Using the previous example:
t = 755.44 Wh Γ· 1000 watts = 0.755 hours β 45 minutes
(Rounded for practicality, this is approximately 45β46 minutes.)
Using the same method, heating 10 litres of water:
- From 20Β°C to 75Β°C takes approximately 39 minutes
- From 20Β°C to 40Β°C takes approximately 14 minutes
Please note: These times assume 100% efficiency and no heat loss; real-world performance may vary slightly.
How Much Warm Water Do You Actually Get?
The MK2 has a 10-litre storage tank capacity, which represents the maximum volume of hot water available. However, water starts to feel uncomfortably hot at 41β42Β°C. When heated to 75Β°C, it is hot enough to cause severe burns, so it must be mixed with cold water to reach a comfortable temperature of 38β40Β°C.
The total volume of mixed warm water (Tmv) becomes the combined volume of hot and cold water. Hence, the formula:
Tmv = Vc + Vh, where Vc is the volume of cold water needed, and Vh is the volume of hot water from the heater's storage tank.
But since there is no fixed value for Vc, it must be calculated using the formula:
Vc = Vh Γ (Th β Tt) Γ· (Tt β Tc), where:
- Th is the temperature of the hot water in the heater's tank
- Tt is the target temperature of the mixed water
- Tc is the temperature of the cold water from the fresh water tank
Example 1: For a target temperature (Tt) of 40Β°C and cold water (Tc) of 10Β°C, the total mixed volume (Tmv) would be 21.6 litres: 10 + [10 Γ (75 β 40) Γ· (40 β 10)].
Example 2: For a target temperature (Tt) of 38Β°C and cold water (Tc) of 20Β°C, the Tmv would be 30.5 litres: 10 + [10 Γ (75 β 38) Γ· (38 β 20)].
What Safety Features Does the MK2 Include?
Like previous Aqueous storage water heaters, the MK2 model includes multiple safety features for reliable performance and enhanced durability. These include:
- Over-temperature protection, which safeguards the heater from overheating by disconnecting the heating element if the temperature exceeds 90Β°C.
- Over-pressure protection, which automatically releases excess pressure inside the tank when it exceeds 0.85 MPa. This relies on the pressure relief valve mounted on the unit's cold-water inlet.
- One-way pressure relief safety valve (provided), mounted on the cold-water inlet. It not only releases excess pressure but also acts as a one-way valve, preventing water in the storage tank from flowing back into the van's main supply pipeline.
- Magnesium anode (inside the water storage tank), which helps prevent rusting of the steel tank by forming a galvanic cell that corrodes preferentially. It also provides cathodic protection by releasing electrons, turning the steel tank into a cathode that cannot rust.
- Blue Diamond enamel coating (inside the tank), which further protects the steel tank from rust and corrosion.
Is the Aqueous MK2 Worth It?
The Aqueous MK2 Water Heater is an excellent accessory for anyone wanting warm showers or hot water for cooking, dishwashing, or cleaning. Although it requires slightly more mounting space than the 6-litre Aqueous models (12V and 240V), the 10-litre storage tank provides a significantly larger total mixed water volume. As shown in the calculations above, this yields between 21 and 30 litres of warm water.
That said, the 1000-watt power draw is substantial for use in an adventure van or boat. It is therefore best used during the day when solar panels are replenishing the battery, while driving (with the alternator charging), or when connected to shore power.
Frequently Asked Questions
How much warm water can the MK2's 10-litre tank deliver?
When heated to 75Β°C and mixed with cold water, the 10-litre tank delivers 21.6 litres of 40Β°C water (with 10Β°C cold water) or up to 30.5 litres of 38Β°C water (with 20Β°C cold water) β enough for multiple warm showers.
How long does the MK2 take to heat up?
Heating typically takes 12β38 minutes depending on the incoming water temperature and your set temperature. By calculation, heating 10 litres from 20Β°C to 40Β°C takes about 14 minutes, from 20Β°C to 75Β°C about 39 minutes, and from 10Β°C to 75Β°C approximately 45β46 minutes.
Can I run the MK2 from a 12V battery bank?
Not directly. The MK2 is rated for 240V at 50 Hz, so it requires a power inverter. If the inverter is dedicated to this water heater, it should be rated at least 1500 W to provide a sufficient safety margin for the continuous high load.
Where should I mount a 10-litre water heater in a caravan?
The unit fits neatly under a kitchen sink at 40.9 Γ 26.7 Γ 26.9 cm. Because it weighs 17.4 kg when full, mount it in a location capable of supporting at least 40 kg for an adequate safety margin.
Need a bigger hot water supply for your van, RV, or boat? Get the Aqueous MK2 Storage Water Heater from Campervan Builders today.
