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Your Heat > Boiler Installations  > How Does Limescale Affect Your Boiler and How to Descale It
Worcester Boiler Installation Sittingbourne

How Does Limescale Affect Your Boiler and How to Descale It

Limescale can reduce the efficiency of your boiler and your heating system and also shorten the life of the boiler. It occurs when the water is full of calcium and magnesium ions that tend to stick on the inside of the boiler and other surfaces, such as pipes. Our experts have dealt with situations like this many times over so here we are sharing our experiences and top tips. Let’s take a look in detail at limescale and its negative effects on your boiler and central heating system, and find out how you can descale the system yourself.

How is Limescale Created?

A hard water area is fertile ground for limescale. Each time your boiler heats water, magnesium ions and calcium carbonate form deposits and, bit by bit, create limescale clumps in your boiler. Limescale is typically found in boilers, taps, pipes, radiators and fittings, such as the inner surfaces of heating elements.

Unfortunately, limescale isn’t a good thing. It creates buildups so your boiler needs more energy to heat water. If you don’t tackle this problem in a reasonable time, limescale buildup will only get worse, which will create even more pressure on the boiler and make your energy bills go up.

Limescale can cause circulation problems in your radiator. If the deposits are thick, hot water won’t be able to circulate at a regular flow, which will reduce your central heating system’s efficiency. (Here’s a list of 6 central heating system maintenance tips that you, as a homeowner or landlord, might be interested in.) Once you notice cold patches on the radiators and room temperatures start to drop, there’s a great chance you are dealing with limescale blockage.

Eventually, metal boiler parts will fail, you are going to be left with no hot water, and your pipes will be blocked. Dealing with the failure of your boiler and, possibly, other parts of your heating system is a costly project (especially if you have to buy a new boiler and replace radiators), so make sure to descale your boiler in time.

How to Descale a Boiler

Removing limescale deposits is a no-brainer, although it would be best to have a professional plumber handle this for you. If you want to try it yourself, the first step is to purchase a commercial limescale remover.

Once you’re ready to start descaling, follow these steps:

  1. Turn off your boiler.
  2. Turn off the ball valve to stop the water flow.
  3. Drain the system by opening all the taps and close them once there is no more water coming out.
  4. Fill your cold water tank with the recommended quantity of limescale remover.
  5. Fill it further with water so the water passes the feed connection.
  6. Turn on the system and wait for a few of hours (4 or so) to complete the descaling process.
  7. Turn on the hot taps every 15 to 30 minutes so hot water runs through the whole system.
  8. Flush the system with cold water as well.

Combi boilers don’t have tanks. If you have a combi boiler, you should descale the heat exchanger directly.


Not only does limescale decrease your central heating system’s efficiency and increase your heating bills, but it can cause major damage to mechanical parts of the system – your boiler and radiators. Try descaling the boiler the moment you start noticing your radiators don’t give off heat as they used to. Or book a job today and one of our professionals will come to the rescue!

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