The Alde “wet” heating system fitted to caravans and motorhomes is loved by owners, many saying they would never go back to a “blown air” system. It operates in the same way as a household central heating system creating hot water for you taps and heat for your radiators. But importantly, instead of using water to carry the heat around to the “radiators”, Alde uses a specific Anti-Freeze.
There are a number of reasons for this;
As the antifreeze ages it becomes less effective and means that your system could be at risk of permanent and expensive damage.
When first built, most caravan and motorhome manufacturers will fill the system with an antifreeze that will degrade and require changing after two years, this fluid is Blue.
The system can be refilled with fresh Blue anti freeze, but Alde recommend that the original Blue fluid is replaced by a specific Pink antifreeze that lasts for 5 Years.
Whilst the Blue antifreeze is cheaper than the Pink, the cost of changing the Blue fluid twice in 5 years far outweighs the extra cost of the Pink fluid that is changed once in the same period.
It's not required to use Alde's own antifreeze, any fluid that meets the "G13" standard can be used.
Incidentally, for topping up purposes, a system filled with Blue antifreeze can be topped up with Blue or Pink fluid, but a system filled with Pink should only be topped up with Pink.
Helpfully, Alde provide a Youtube video explaining the fluids that can and can't be used.
A special arrangement of pumps, valves and hoses supplied by Alde are used to complete a fluid change. The system is drained at the boiler, capturing the old antifreeze.
New antifreeze is then pumped into the system which pushes out any remaining old fluid into a container. Once all the old fluid is pushed out and new fluid is seen, the valve positions on the Alde tool are changed and the fluid is then circulated around the caravan pipework at high speed to remove any air trapped in the system.
After 15 minutes of running, the system may be bled at high points to ensure its air free.
After removal of the pump and pipes, the reservoir is topped up and the system run up to check even heat output.
In the worst case scenario, when the inhibitors in the antifreeze become weak, the boiler can corrode to the point where it fails and will no longer work. This is a super expensive item to replace. Parts of the system may no longer work (for example 240v heating) You may also find that heat transfer is less effective.