How Long Should a Combi Boiler Last? Re April 26, 2022

How Long Should a Combi Boiler Last?

Ideal boiler in the kitchen

Generally speaking, a modern combi boiler should last you between 10 to 20 years, at the very minimum. Now, this figure obviously varies on the quality of the model, installation and the level of upkeep and maintenance afforded your boiler; if you don’t look after your combi boiler very well, then it’ll come as no surprise that it might not last quite so long.

In this blog, we’re going to look at some of the most common questions around combi boiler longevity, including those on when a combi boiler should be replaced, what a combi boiler is, how they work, and how in turn that affects their durability. First, though, what actually is a combi boiler?

What is a Combi Boiler?

Combi boilers are the most common type throughout the United Kingdom, providing a combination (hence ‘combi’) of both hot water and central heating from within one singular unit. Their popularity lies in their comparatively compact size, high efficiency and overall affordability when compared with other boiler types and models.

Boiler installation costs vary based on boiler make, size, location and other factors.

How Does a Combi Boiler Work?

We’ll not go too in depth here as to the workings and machinations of your average combi boiler, rather give a quick, simple overview:

  • When the thermostat falls beneath a certain set temperature, it sends a signal to the boiler.
  • The boiler then fires up and fuels the central heating until it reaches the thermostat temperature, again.
  • For hot water, you simply turn on the hot water tap for instant hot water, as one of the boiler’s valves directs the heat towards the hot water supply, negating the need for a bulky hot water storage tank or cylinder.

Which Combi Boiler Models Last the Longest?

As with any product, certain brands and models are better made than others, and combi boilers are no exception to this. The most efficient, long-lasting boilers come (arguably) from manufacturers ViessmannAlpha and Vaillant. Particularly reliable are the:

  • Viessmann Vitodens 100-W 30kW
  • Alpha E-Tec
  • Vaillant ecoTEC pro

Other combi boiler models from Worcester BoschIdealGlow-Worm and Baxi are also popular, although they tend to score slightly lower on reliability tests. At the same time, though, it’s worth stating that the differences are only slight, and most modern boilers are at a very high level, indeed, these days.

How Often Should You Replace a Combi Boiler?

It depends on how old your combi boiler is; if you’re reading this, and your combi boiler is already 10 years old, then it might well (as an older model) be nearing the end of its reliable lifespan. An experienced boiler engineer will be able to tell you from the model you’ve got just how long your boiler will last you, there or thereabouts.

If, on the other hand, you’re reading this looking to buy a brand new combi boiler, then today’s offerings will generally last you a minimum of 15 years. If you look after it well, however, there’s no reason why that figure shouldn’t be pushed upwards towards 20 years, if not more.

ideal boiler image

What Variables Affect a Boiler’s Lifespan?

There are many variables affecting a boiler’s overall lifespan, including: age, servicing frequency, build quality.


We touched on this before, but it really can’t be stressed enough what a difference a boiler’s age can make in terms of its lifespan/durability. Older boilers are less efficient, which means they’re putting in more energy (or work) for the same results as their more efficient counterparts.

If you have two boilers, and one is putting in ten times the amount of work, for example, as the other boiler, over a five-year span, let’s say, then the less efficient boiler is unsurprisingly going to be more run down, more quickly.

Servicing Frequency

If you have a car, and take good care of it – perhaps getting it serviced every year, and making sure it passes its MOT – then the chances are it’ll last you a fair while. By comparison, if you leave your car exposed to the elements and never get it checked over, then it’s no surprise that it doesn’t last as long.

The same can be said for your combi boiler; boiler engineers recommend that you have your boiler serviced once every 12 months. That way, the boiler’s main components can be removed and cleaned, and any minor issues addressed before they develop into major issues.

Build Quality

Even the best, most reliable boiler brands will have more entry-level market offerings which won’t last as long as their top-of-the-range alternatives.

These ‘budget’ options (which, ironically, are still often very expensive) are, unsurprisingly, often built with slightly cheaper fittings, and mightn’t feature the same state-of-the-art technology that their stellar siblings do.

As a result, they might last a couple of years less than the more expensive option from the very same manufacturer.

Boiler in cupboard

Can a Combi Boiler Last 20 Years?

Yes! There’s no reason why (provided that you regularly service your boiler and that it’s a relatively new model) your boiler shouldn’t last 20 years, if not longer. Their efficiency naturally lends itself to a longer-lasting boiler, and we’d recommend getting a combi boiler over a conventional system boiler if the lifespan is your main influencing factor.

Final Thoughts…

Whether you’re looking for a brand, shiny new boiler, or simply have some questions about your boiler, then the team here at WarmZilla would love to hear from you!

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