Buying and fitting a new boiler is one of the more expensive investments you’ll make in your home. It’s in the same ballpark as getting double glazing on one side of the house, or having your home re-wired. So, home-owners naturally want to know what kind of value for money they are getting from their boiler – and that means how long it’s going to last.

In this article we’re going to look at how much life you can expect to get out of your boiler and factors that affect its lifespan.

Average lifespan of a boiler

Most boiler manufacturers and fitters put a similar timescale between new installations, and it’s usually around 15 years.

If 15 years seems low, it’s probably because you grew up with a trusty old boiler that survived two world wars and kept on providing hot water for the whole family, perhaps courtesy of the occasional whack with a hammer. What you’re not taking into account is how efficient it is. Yes, boilers, even modern ones, will in theory last longer than 15 years. But that’s about how long it takes to become so inefficient that it’s more cost effective to buy a new one – and let’s not forget about its environmental impact, of course.

If you’ve ever seen the inside of a boiler, you’ll see straight away that it’s a complicated piece of kit. It’s full of moving parts like pumps, expansion vessels and valves, several metres of pipework, a burner and various electronic components. All of these parts, no matter how good quality they are, wear out at different rates.

Factor in that a boiler is a piece of machinery that is regularly going between hot and cool, which means it’s constantly expanding and contracting, and that leads to fatigue and stress on pipework and joints.

There are some other aspects that influence the lifespan of your boiler, and we’ll look at these next.

Service history

When you buy a new boiler, you’ll usually be told to have it serviced one year later, and then at the same time every year thereafter. That is for three reasons:

  1. To keep your boiler safe
  2. To keep it maintained and efficient
  3. To protect your warranty

As we described above, boiler parts do wear out, but that doesn’t necessarily mean that the boiler becomes useless. Components can be cleaned, repaired and replaced, and that’s why making sure you have your boiler serviced annually will extend its lifespan and maintain its efficiency.

As homeowners don’t tend to take their boiler with them when they move out, you usually inherit a boiler when you buy a house. If you can, find out if it has a full-service history and when it was last seen by a professional boiler engineer. It’s a good indication of how worn out its components will be, and that will give you an idea how efficient it is – and how likely it is to break down.

If it’s had a good service history, book an engineer when it’s next due. If it’s not been checked for more than a year, make it a priority to book a service.

Limescale v timescale

Limescale is a deposit of calcium carbonate. If you know your chemistry, that’s the same compound that makes up chalk, limestone (hence the name) and marble. If you can see a white flaky layer on your kettle elements or boiling pans, that’s limescale.

Limescale comes from calcium bicarbonate that occurs naturally in water in hard water areas. There’s no hard and fast rule, but generally, if you live in the South, East or Midlands of the UK, you’re probably in a hard water area, because of the chemical makeup of your water supply.

There’s a chemical reaction that converts the bicarbonate into carbonate, and that will start to crystallise on the insides of your pipework, pumps and even closed systems like radiators. It’s unavoidable and slow, but given enough time, the crust of limescale will start to block your pipes to the point where they become inefficient.

Because there’s a constant supply of fresh water going through your boiler, and because heat speeds up the reaction, boilers are particularly prone to limescale build-ups. While some can be cleaned away during servicing, it’s likely that the limescale build-up will shorten the life of your boiler.

On the plus side, if you live in a soft water area, or have a water softening device installed, you can add a few years to the expected life of a boiler.

How do I know it’s time to replace my boiler?

As a homeowner, this is probably not a decision you should make. If you’ve noticed your boiler is making strange noises, losing pressure, or if your hot water is coming out slowly or not very hot, your first call should be to a boiler engineer. It’s possible they might be able to fix it.

If your boiler is approaching its 15th birthday, however, it’s probably worth looking into replacing it or at least ensuring you have the finances in place to do so. Boiler technology is always progressing, and the most significant changes of the past 15–20 years have been in their efficiency.

Getting a new boiler will help keep your gas bills down, can increase the value of your home and will reduce your carbon footprint. So, although it may come with a price tag, it can save you in the long term, especially compared to a boiler that’s 20 years old or more.


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