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Top 5 Quietest Combi Boilers

Quietest combi boilers

The quietest combi boilers are about as noisy as modest rainfall.

So if your current boiler is so loud you can hardly hear yourself think, it doesn't have to be that way. Replace it with a modern condensing boiler and you'll hardly hear a peep as it heats your home.

To help you in your search for a warm and peaceful life, we've ranked the quietest boilers on the market. We'll also reveal which are Quiet Mark approved.

How loud should a boiler be?

The sound from a boiler is measured using the decibel scale. Decibels (db) are a measurement of sound intensity starting from 0db. The louder the sound, the higher its decibel rating.

The lowest audible sound is silence – recorded as 0db. Any sound 10 times more intense than silence, like breathing, hits 10db on the scale. A sound 100 times louder than 0db, let's say whispering, will be recorded as 20db. And so on.

A modern condensing combi boiler has a sound level of somewhere between 40 and 60 decibels as it heats a home. Similar to moderate rainfall or the average library.

Quietest combi boiler

Quiet Mark explained

The Quiet Mark award helps you to find a boiler that won't disturb you. You'll notice this logo on other household appliances like fridges too.

Boiler ranges certified by Quiet Mark include:

  • Glow-worm Energy
  • Ideal Logic Max
  • Ideal Logic Plus
  • Vaillant ecoFIT Pure
  • Vaillant ecoFIT Sustain
  • Vaillant ecoTEC Exclusive Green iQ
  • Vaillant ecoTEC Plus
  • Vaillant ecoTEC Pro
  • Vaillant ecoTEC Sustain

It's important to extend your search for a quiet boiler beyond Quiet Mark as they're only given to boilers made by Glow-worm, Ideal and Vaillant.

Quietest combi boilers ranked

The quietest combi boiler is the Worcester Bosch Greenstar 2000. Its decibel rating of 43 means that it wouldn't be out of place in a library.

We've ranked the quietest combi boilers by their decibel rating.

Quietest Combi Boilers ErP Decibel Rating (dB)
Worcester Bosch Greenstar 2000 (25 & 30) 43
Ideal Logic Max C35 44
Vaillant ecoTEC Plus 838 45
Vaillant ecoTEC Plus 938 45
Viesmmann Vitodens 200-W 30 46
ATAG i24C 46
Ideal Logic Max C30 46
Ideal Vogue Max 26 47
Baxi 825 48
Baxi 830 48
Glow-worm Energy 25C 49
Ariston Alteas One Net 30 51
Biasi Advance Plus 7 25 52

A quiet combi boiler is well suited to small-medium sized homes with 1-2 bathrooms. If you live in a larger home with multiple bathrooms then you'll need a system or regular boiler. Compare the quietest regular and system boilers.

Top 5 quietest combi boilers

There you have it, the quietest combi boilers on the market ranked. Now let's take a look at the top 5 in more detail.

Quietest Combi Boilers Central Heating Output Domestic Hot Water Output Max. Warranty Potential Cost
Worcester Bosch Greenstar 2000 (25 & 30) 20 kW 25 – 30 kW 6 years £730 – £850
Ideal Logic Max C35 24.2 kW 35.3 kW 10 years £1,156
Vaillant ecoTEC Plus 838 30.1 kW 38.7 kW 10 years £1,408
Viessmann Vitodens 200-W 27.8 kW 30.5 kW 12 years £1,550
ATAG i24C 23.2 kW 26.6 kW 14 years

1. Worcester Bosch Greenstar 2000

Worcester Bosch released the Greenstar 2000 range to make their premium heating systems available at a more affordable price. There are two Greenstar 2000 boilers and both have an ErP decibel rating of 43 making them the quietest on the market.

  • A Quick Tap feature reduces water waste
  • 6 year guarantee when fitted with a Greenstar System Filter
  • The C6 heat exchanger is covered by a 10 year guarantee
  • Also available in LPG for off-grid properties

2. Ideal Logic Max C35

Ideal is a leading name in the UK heating industry. The Logic Max range of boilers are highly efficient and have been designed to fit seamlessly into your home.

The Logic Max C35 came very close to the top spot but just missed out. This model puts out a sound level of 44db while the C30 has a decibel rating of 46.

  • Designed for a compact installation within a cupboard
  • Includes frost protection to keep it running through the winter
  • A low lift weight can help to keep installation costs down
  • Lengthy 10 year warranty as standard

3. Vaillant ecoTec Plus 838 & 938

Vaillant boilers are well known for performing efficiently. This means they can help to lower your heating bills. The 838 and 938 are the most powerful boilers in the range and both have a noise level of 45db.

  • Can perform at 1:6 of its top power (known as modulation ratio) to lower energy consumption
  • Frost protection for reliable heating year-round
  • Standard warranty of 5 years
  • Option to extend the warranty to up to 10 years
  • LPG model available

4. Viessmann Vitodens 200-W 30

Viessmann boilers are recognised for their efficiency. This particular range is able to perform at 98% efficiency at times – which is very high. Add that to its low noise levels and you have a combi boiler well worth considering.

  • Can perform to efficiency levels of up to 98%
  • Incredibly wide modulation ratio of 1:17 meaning that it can lower its output rating to reduce the energy it uses
  • Compact design
  • Option to extend the warranty from 5 to 10 years

5. Atag i24C

ATAG boilers are widely recognised as being reliable and highly efficient. This is backed up by their extensive warranties of 10-14 years.

  • Only 275mm deep which allows for installation in a cupboard
  • Built-in frost protection
  • User-friendly controls
  • A 10 year warranty as standard
  • Warranty can be extended to a very lengthy 14 years
  • Lifetime replacement guarantee on the stainless steel heat exchanger

Quietest system and regular boilers

System and regular boilers run at similar noise levels to combi boilers. However, the quietest system and regular boilers have a lower decibel rating than the quietest combi boiler.

Quietest system boilers

Quietest System Boilers ErP Decibel Rating (dB)
ATAG i15S 37
Ideal Logic System S15 44
Worcester Bosch Greenstar 9i System 49
Ariston Clas System One 49

Quietest regular boilers

Quietest Regular Boilers ErP Decibel Rating (dB)
ATAG i15R 37
Viessmann Vitodens 200-W Open-Vent 26 39
Ideal Logic Max Heat H15 41
Worcester Bosch Greenstar 12Ri 45

Why is my boiler making noises?

An unhealthy boiler will make all sorts of noises. From banging and clunking to gurgling and whistling.

If your boiler has started to make a concerning noise then you'll need to find the cause of the problem. The best way to do this is by hiring a Gas Safe registered engineer. They'll then be able to fix the problem too.

Having said that, based on the noise you're hearing we can potentially find the cause.

Boiler Noise Possible Reason
Banging A build-up of debris
Dripping A leak
Gurgling Air trapped in the system
Humming High pressure
Tapping A part has come loose
Whistling Build-up of sludge and limescale

Noticed one of these boiler noises? Then find the cause and how to fix it in our guide to noisy boilers.

How to reduce noise from your boiler

Quiet boiler
As a boiler ages it's likely to get noisier. To keep it running as quietly, reliably and efficiently for as long as possible, we highly recommend having it serviced annually.

However, there will come a time when you need to find a new boiler. You should start thinking about a new boiler after around 8 years. If your boiler is 15 years or older then getting a new boiler should be at the top of your to-do list. You can get free quotes for a new boiler here on Boiler Guide.

If your boiler is fitted in a room where you spend a lot of time, like a bedroom, then it's worth soundproofing the cupboard (if it's in one).

How to soundproof a boiler cupboard

If your boiler is fitted in a cupboard then there are a few things you can do to keep the sound down. Your options for soundproofing a cupboard include acoustic panels or carpet tiles. Both of these line the inside of the cupboards – effectively acting as a form of insulation.

An alternative idea is to hang thick curtains around the cupboard. This is unlikely to be practical in many homes but is worth considering.

Get quotes for a quiet boiler

If you have an old noisy boiler then it could be time to consider a replacement. Not only are modern boilers quiet, they're also safer, more reliable and able to reach higher efficiency levels.

Finding a heating engineer to install a new boiler used to be a challenge but we've made it easier than ever. Simply complete our online form and up to 3 local installers will be in touch as quickly as possible. Each will give a quote for the installation of a new boiler for you to then compare. You're free to turn down any of the quotes you receive.


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Adam

About the author

Adam

Adam is our lead content writer who spends most of his time researching and writing articles for the Boiler Guide website. You can rely on him to keep you up to date about the future of home heating.

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