WHAT IS LIMESCALE?
Limescale is the general name for a deposit on water pipes and fittings formed from
naturally occuring calcium bicarbonate when water is heated.
HOW IS LIMESCALE FORMED?
Calcium bicarbonate is found naturally dissolved in water in certain regions.
Normally the calcium bicarbonate stays dissolved in the water, but it changes to calcium
carbonate once water is heated to 70oC.
Calcium carbonate tends to separate from water and it clings to nearby surfaces, causing
the white scaley deposit seen inside kettles and known as 'Limescale'.
WHAT DOES LIMESCALE DO TO PIPES?
On central heating systems and in hot water tanks and pipes the calcium carbonate
forms a lining which grows thicker over time.
This gradually makes the inside of hot water pipes and tanks narrower as the layer
of calcium grows thicker. Eventually pipes become blocked completely.
WHAT DOES LIMESCALE DO TO IMMERSION HEATERS?
Around heating elements such as immersion heaters in hot water tanks, the limescale
grows until it is too thick for the heat generated by the immersion heater element
to be transferred into the surrounding water.
The trapped heat then builds up in the immersion heater rod causing the immersion
heater rod to burn out and fail.
WHAT DOES LIMESCALE DO TO BOILERS?
In central heating boilers the limescale builds up in the pipes running the heated
water through the boiler, particularly in the area where gas energy is used to heat
water (known as the 'heat exchanger'). The limescale build-up slows down the
heating process and the flow of water, making the boiler less efficient and eventually
causing boiler failure.
HOW CAN LIMESCALE BE PREVENTED?
In central heating systems limescale can be prevented by using a chemical descaler
and protective additives in the water. These additives need to be changed every 12-24
months, depending on the amount of calcium in the local water supply.
Limescale can also be prevented by the use of chemical water softeners or electo-magnetic
water conditioners, but a separate supply of untreated water for drinking must always
be available in the property.