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ALDE Heating Fluid Change

 Alde logo  Alde boiler 3020


Advantages of the Alde Compact System, and the importance of replacing the fluid within the system.

Alde first released their 'Hydronic Radiant Heating System' for caravans and motorhomes in 1966. Founded in Sweden in 1949, Alde is the world-leading specialist in this technology.



Fluid is a more efficient way of delivering heat than blown air. The Alde system can heat the smallest, and largest of leisure vehicles evenly from front to back. Drawing around 1 amp from the leisure battery, even in winter. It is an ideal solution for those who wish to operate off the grid for longer periods.


Space Saving

Alde Compact boilers use lightweight aluminium pipework and finned convectors routed behind vented furniture. There is no ducting intruding on storage space.

The Alde 3010, 3020 and the most recent 3030 Compact boilers are the smallest and lightest combi boilers in the world.



The fluid is unpressurised and can be circulated around the central heating system by a near silent, low power pump. There are no forced air fans.



The human body has a very sensitive to rapid temperature change, which makes us feel too hot or too cold. When heat loss is balanced with the environment, the body feels comfortable. Hot or cold draughts, cold walls and floors, and varying temperatures from one room to the next, all make us feel uncomfortable.

Alde central heating can be routed to all areas of a caravan or motorhome, even inaccessible areas that could draw heat away from the living space. Heat from convectors rise up the walls and across the windows, acting as a warm air barrier against draughts. The warm air rolls over at ceiling height, creating an even heat from floor to ceiling, in front of and behind furniture, warming through the interior.

When the boiler powers down and is using less fuel, the central heating continues to emit heat, avoiding rapid changes in temperature and ensuring total comfort.



Alde central heating minimises disturbance of particulates, and the routing of the aluminium pipework around the interior can actively reduce damp, mould, mildew and condensation too.


Added Value and Residuals

Vehicles fitted with Alde central heating are more attractive to consumers, and fetch a premium over vehicles without, on both new and second-hand markets.


Reliability and Service

Built to withstand the harshest Scandinavian Arctic winters, the 3020 Compact boiler is the heart of one of the most reliable central heating and hot water systems in the world. The boiler itself has no service requirement.

The popular 3020 Compact boiler was released in 2014 and is the third iteration of Alde boilers using the Compact form factor, first released in 1990 with the 3000 boiler. The second iteration was the 3010 boiler, released in 2004 and still found in thousands of older leisure vehicles throughout the UK today.

The 3030, launched in 2022 for the 2023 market, is the most recent addition to the Alde family of Compact boilers.

Alde has been voted the best heating system for 12 years running, by the readers of Reisemobil International (2009 - 2020).


Alde service pumpAlde header tank


 What is Alde Heating and Why Change the Fluid?

Alde supply central heating units for motorhomes and caravans. A case surrounds an 8.4ltr water cylinder heated by the Heating Transfer Fluid (HTF) chamber, which is heated by the combustion chamber in the centre. The system is powered by LPG gas or 230v AC elements (1Kw & 2Kw) as required. The space heating side of the system can be used with or without water as the heat is transferred via the fluid (HTF).

To heat the living space, the fluid (HTF) is pumped around aluminium pipework and radiators in exactly the same way as a domestic central heating system, except that instead of using plain water, the Alde system uses antifreeze. There are several reasons for this;

  • It protects the heating system from freezing so you don't need to drain and refill it (though you must still drain down the hot water system, so the boiler is not damaged by the water freezing in the tank, taps and pipework).
  • It contains inhibitors that prevents corrosion of the boiler and pipework so that the system remains clean and efficient.
  • It conducts the heat more efficiently.

Replacing The System Fluid/Anti-Freeze

Most older motorhomes and caravans were built and supplied with a blue coloured antifreeze installed. This degrades and requires flushing after 2 years and replacing with the pink coloured 5 year fluid. If it's not changed, it becomes less effective as an antifreeze and corrosion inhibitor, and could put your system at risk of damage or costly replacement.

Alde recommend that the original blue fluid is replaced by a specific pink G13 antifreeze that lasts for 5 years. Whilst the blue antifreeze is cheaper than the pink, the cost of changing blue fluid twice in 5 years far outweighs the extra cost of the pink fluid (changed once in the same period).

Topping Up 

For topping up purposes, a system filled with the blue 2 year anti-freeze should not be topped up with the pink 5 year fluid, and a system filled with pink fluid should only be topped up with pink, to a level no more than 1cm above minimum in the header tank when cold.

Any Alde system that is currently filled with the blue 2 year fluid, should be replaced with the pink 5 year fluid, without delay!

What if I Don't Change the Fluid in Time?

In the worst case scenario, when the corrosion inhibitors in the antifreeze become weak, the boiler can corrode to the point where it leaks and will require replacing. This is a very expensive item to replace. If this occurs, other parts of the system may no longer work (for example 240v heating).

Trained and Certified by Alde

As an Alde approved engineer, I can change the heating fluid in your motorhome or caravan at your home, office, storage area, caravan pitch or at our Milton Keynes premises.

Coverage and Cost

Based in Milton Keynes, we cover most of Bedfordshire, Buckinghamshire, Northamptonshire, Oxfordshire, South Leicestershire and Warwickshire.

An Alde heating fluid change service currently starts at £220.00 (if booked independently). Or as low as £170.00 (if booked and carried out at the same time as one of our fixed price caravan or motorhome services).


Alde servicing logo