What causes limescale?

Limescale comes from the remnants of dissolved minerals such as calcium carbonate, magnesium or gypsum present in our water supply.   

When it rains, the water filters through limestone and chalk and collects in an underground layer called an aquifer. Our water suppliers, extract the water, filter it and pump it out into our homes, offices, factories and public buildings. Despite the extensive filtration process, these dissolved minerals can still end up in our water.  

If the ground where you live is made up of granite, then limescale won’t affect you as much. You’re in a soft water area. Where the ground is made of limestone and chalk are hard water areas.  

Limescale is harmless enough to drink but it’s not good for your boiler, heating system or water heater.  

What can limescale do to my boiler?

It will reduce the efficiency of your boiler and can increase your gas or electric bills. If it’s left too long then it can cause premature failure of valves, pipe blockages and household appliances. 

We’ve all seen the white flakes in our kettles. As water is heated, the particles cling to internal parts such as metal pipes and the heat exchanger. Over time, limescale will start to form a layer on your heat exchanger that will act as an insulator.  

This means your boiler will have to work harder and harder to heat your water, which costs you.  

How can I reduce buildup of limescale in my boiler?

You need to know how hard your water is. You also need to know which components have contact with the water and plan what measures you can take to prevent the buildup.  

There are many limescale protection devices on the market. With a combustion boiler, a simple magnetic in line scale reducer may be sufficient. You may wish to use a unit that provides a coating to the inside of a heat exchanger that prevents scale sticking.  

Another way is to have look at the way any installed equipment could aid the process and reduce the risk. Such as the ACV Smart cylindersHeatMaster combi boiler and water heater and HRs range.  

How do ACV Tank-in-Tank water heaters reduce the buildup of limescale?

The ACV tank-in-tank water heaters are designed to reduce limescale. The accumulation of limescale is reduced thanks to the corrugated design of the internal tank.   

When hot water is drawn off there’s a slight drop in pressure. When the draw-off tap is closed, there’s a slight increase in pressure.   

This causes the internal tank to expand and contract ever so slightly. It's this ‘wobble’ that stops the limescale clinging to the inside of the tank and prevents buildup over time. For a more detailed explanation of the benefits of Tank-in-Tank visit our FAQ page.   

How can I find out if I live in a hard water area or not?

Most of the south east of the UK is hard water, the Midlands are medium to hard and the north of England, Scotland, most of Wales and Cornwall are soft water areas.   

How do I get rid of scale in my boiler if it has built up?

You'll need to book an inspection with a Gas Safe engineer. They’ll be able to check to see if there has been a buildup and can remove the limescale if necessary.  

This is why it’s important to have your boiler or water heater serviced on a regular basis. You’ll be able to avoid the problems limescale causes.