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Water Heater De-scaling


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How often this needs doing is obviously variable - it depends how much you use hot water as well as how often you caravan in hard water areas.


It's probably best done immediately after sterilising and draining the water system. Ensure that any filter elements are removed.


Pop down to your local supermarket and get 5 litres of vinegar. It seems to be cheaper as 9x 564ml (1pint) bottles than a 5 litre container. Pour the vinegar into you external water container. Dilute the vinegar 50% by adding 5 litres of water.


Refill the caravan water system, eliminating all air from the pipes.


Turn on the water heater (at full temperature 70 degrees if gas). Leave for several hours.


Turn off the water heater and drain the system down. Re-fill the system with fresh water and drain down again to rinse out the vinegar.


Job done, just 9x 16p = £1. 44, using only food grade materials.


I've never seen a caravan service schedule, not even from an Approved Caravan Workshop, which includes this but it does need doing! I do mine annually.

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  • 3 weeks later...
I didnt think the water heater was that prone to scaling as the water doesnt actually boil, the impurities dont become a problem.


Could be a valid point. ......lets see what transpires.



When water is heated, the calcium and magnesium salts which cause hardness become less soluble. They precipitate out as scale. You don't have to boil the water to cause the scale, only heat it. If you live in a hard water area and you ever have to replace the immersion elements in a domestic hot water tank, you'll be horrified at the depth of the deposits through which heat was trying to fight.


If you've ever put hard water in your caravan system, you'll have scale in the water heater, though it will slowly redissolve if you normally fill up with soft water.


Descaling with vinegar (acetic acid) is a very good tip as commercial descalers are generally highly toxic (they often use formic acid) and require considerable rinsing out after use. Because the odour of vinegar is so distinctive, even when highly diluted, you can easily tell if you've you've underdone the rinsing by the taste/smell of the water without putting your health at risk.

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