Top 5 Quietest Boilers on the Market Re February 16, 2021

Top 5 Quietest Boilers on the Market


Working from home has become the norm for a lot of us since the pandemic, which can be challenging at the best of times – screaming toddlers, cats clawing up your clothes during Zoom meetings and the call of delicious snacks coming from your cupboard. Here at WarmZilla, we also understand how distracting a noisy boiler can be.

Although all boiler ranges are available in different kW outputs depending on the number of radiators you have in your home and the overall demand for central heating in your home, the kW output is not a reason why they could become noisy.

However, some boilers have louder dB scaling than others. Not sure what dB scaling means? Don’t worry, we’ve covered it later on in the blog. Moreover, this blog aims to discuss the top 5 quietest combi, system and regular boilers on the market to help you choose the best one for your home so you don’t get distracted.

But first, let’s talk boilers. We know this may be self-explanatory to many, however, it is important to get to know your boiler, or know everything you need to know before you buy a new or replacement boiler. If you want to know more information and advice on the best boilers to buy in 2021, we’ve got this covered, or even better, we have a Boiler Comparison tool that allows you to compare up the three boiler models or brands at one time, to help you find the ideal new boiler for you home. 

What is a boiler and how does it work?

The boiler is the most essential part of your central heating system, producing heat for your home. Essentially, a boiler is a small furnace that uses gas, oil, or LPG to fuel its operation. 

In the UK, the majority of boilers are fueled by natural gas which feeds automatically through the national gas grid. 

Boilers are often installed inside your standard kitchen cupboard, although they can be placed in any room of the property, outside, or in the garage. 

How do boilers work you ask? They utilise natural gas, similar to how a water heater would work however, there is a difference between how a combi, system and heat-only boiler work, so here are the differences:

How does a combi boiler work?

A ‘combi’ boiler is short for a combination boiler. It is called this because it is a single unit which serves two functions, heating and hot water. One of the key attractions of a combi boiler is that no separate water heater is required. A combi boiler takes water directly from the mains water supply. When you need to use the hot water, you simply turn it on, the gas burner is ignited and the heat exchanger transfers the energy to the water, heating it.

A combi boiler is ideal for those who need hot water on demand, as it is generated almost instantly.

How does a system boiler work?

A system boiler has its cold water delivered directly from the mains supply. The water is heated via the heat exchanger, which transfers the energy to the water, heating it. However, once heated the water is then pumped into a hot water cylinder, where it can be stored until needed. System boilers are ideal for homes that have more than one bathroom or need a constant flow of hot water from different taps or showers in the house.

How does a regular boiler work?

Regular boilers, also known as heat-only boilers, need an additional large tank to store cold water (this is usually installed in the attic of your home). The cold water from the tank in the loft is then fed down to the boiler. This is why the expansion tank needs to be installed as high above your boiler as possible, to increase the pressure of the water in your system, to help make its way down. 

Once the boiler is ignited, the heat exchanger then gets to work heating the water. The heated water is then pumped to a hot water storage cylinder, where it is then sorted until you need it. Due to its large size, the regular boiler is not recommended for smaller homes with limited space.

Now, the real reason we are here is to find the 5 quietest boilers on the market. But before that, as mentioned above, here’s a bit about what dB scaling is and why it is important to consider when purchasing a new or replacement boiler.

What is a decibel scale (dB)?

Noise is measured with a sound level meter that measures the intensity of noise, this is called a decibel unit (dB). 

The human ear is an amazing hearing device, which has a built-in mechanism that helps to reduce its own sensitivity to the sounds going on around it. It has the remarkable ability to handle an enormous range of sound power levels, from a pin dropping close by to an extremely loud jet engine far away. 

If a sound reaches 85 dB or stronger, it can cause permanent damage to your hearing. The amount of time you listen to a loud sound affects how much damage it will cause. Luckily, a boiler can range from 30dB or 60dB, depending on the model and manufacturer. 

So, now we know why it’s important to consider a boilers dB scaling when purchasing a new or replacement boiler. Let’s take a look at the quietest boilers on the market.

Top 5 quietest combi boilers

Viessmann Vitodens 200


The Vitodens 200-W is a high specification gas-fired hot water boiler. It is one of the most efficient and quietest condensing boilers in its class. With noise emissions of 36 dB, making it one of the quietest boilers on the market. Viessmann’s fantastic reputation as one of Europe’s largest manufacturers of boilers means you can rely on their products.


  • Low emission combustion with Viessmann made stainless steel Matrix cylinder burner
  • Extremely quiet operation – quieter than most refrigerators
  • Uses a “No Permanent Pilot Light” ignition system
  • Wall-mounted for fast installation and reduced maintenance 
  • Inox-Radial heat exchanger surface and Matrix-compact burner
  • Compact dimensions, only 450 mm wide
  • Optionally available as combi or system boiler

Worcester Bosch Greenstar 2000

WB 2000

The Greenstar 2000 is a highly efficient combi boiler, suitable for apartments, small and medium-sized homes with one bathroom. Available in outputs of 25 and 30kW, the Greenstar 2000 25kW and 30kW combi boilers have a noise level of 43 dB. Also available in LPG, it is an excellent option for caravans, static homes and holiday parks.


  • Compact cupboard fit
  • Large back-lit display
  • Low lift weight 
  • A fully modulating operation to low outputs
  • Energy efficiency rating Class A
  • Made in the UK 

The Grant Vortex Pro XS 26

The Vortex Pro 26 Floor Standing ErP is a compact and exceptionally quiet combi boiler with a noise level of 41 dB. This 26kW combi boiler was designed with the engineer in mind. It’s simple and quick to install and doesn’t need complicated wiring or plumbing.


  • Large plate heat exchangers reduce the water content
  • An increased surface area that improves hot water performance
  • Safety features include a low system pressure cut-off switch which protects the boiler in the event of system water loss
  • Two accurate electronic temperature controls that allow the boiler to operate condensing mode on central heating whilst maintaining instant hot water production
  • Built-in frost protection, neon diagnostic indicators, and a factory fitted internal condensate trap
  • Outputs of 21, 26, and 36kW to suit a range of properties.

Ideal Logic+ C35

Ideal Logic with 8 year guarantee

The most popular option on the market for the most discreet boiler is the Ideal Logic+ range. Why? Because of one compelling reason; the Quiet Mark.

According to the Quiet Mark website, “through scientific testing and assessment, Quiet Mark identifies the quietest products in a given category giving consumers a more informed choice about the products they buy. The Quiet Mark scheme drives designers and manufacturers to reduce sound levels in their products enabling consumers to enjoy a less stressful domestic soundscape”. 

The Ideal Logic+ C35 has the lowest dB level of 44. However, this combi boiler is suitable for larger homes with up to 20 radiators, which may be too powerful for your home. Moreover, the Ideal Logic+ C24 has a noise level of 48 dB, and the C30 has is 46 dB, both well within the safety limits. 


  • Supported by the Queen’s Award for Enterprise 2013
  • Received the Good Housekeeping Reader Recommended Status in 2013 and 2017
  • Built-in frost protection
  • Made in the UK
  • Quiet Mark
  • Energy Saving Trust endorsed 
  • User-friendly controls
  • Backlit LCD display screen

Vaillant EcoTec Pro 30


The Vaillant EcoTec Pro is a combi boiler, ideal for small to medium-sized homes that do not have a high demand for hot water. Additionally, all of Vaillant’s boilers are Quiet Mark approved (the international award program that encourages companies to design technology with noise reduction in mind) and their quality boilers can last for over a decade.

The Vaillant EcoTec Pro 30 has a noise level of 49 dB, making it one of the quietest combi boilers on the market. 


  • A heating output of 24kW and hot water output of 30kW
  • The ability to efficiently heat and supply hot water to a medium-sized three-bedroom house
  • You can fit it on your kitchen wall or hide it in a storage cupboard
  • The patented ‘Aquacomfort’ system gives you access to instant hot water at regular temperatures
  • The Pro 30 has 7 years guarantee when fitted by a Vaillant accredited installer
  • Removable side panels and push-fit flue system

Combi boiler comparison table

MakeViessmann GrantWorcester BoschIdeal Vaillant 
ModelVitodens 200Vortex Pro XS 26Greenstar 2000 (25+30)Logic+ C35EcoTec Pro 30
dB Scaling3641434449

Top 5 quietest system boilers

Worcester Bosch Greenstar 4000


The Greenstar 4000 is Worcester Bosch’s latest boiler. This boiler is available as a combi and a system boiler. The Worcester Bosch Greenstar 4000 system boiler is available in five different kW outputs of between 12kW and 24kW and carries the same guarantee lengths as its predecessor the Greenstar i, of up to 10 years with WarmZilla. 

This system boiler has a dB of 42, making it a very quiet and efficient boiler.


  • 100% planet-friendly packaging
  • Full-colour display 
  • Front access to all components 
  • Quiet operation
  • Easy to use controls
  • Easy to read display screen
  • Modulates down to 1.9kW central heating output
  • 500ml condensate siphon
  • Longer flue lengths up to 12m (60/100)

Ideal Logic Max


The Ideal Logic Max System Boiler has the same great award-winning features as our Logic+System with the addition of a high-quality Ideal System filter. This system boiler has been designed with a compact cupboard fit, making it a discrete and reliable option for your home.

The Logic Max System Boiler is compatible with our Ideal controls and displays a service reminder, helping you to get the most out of our boiler. The Logic Max boiler is also one of the quietest system boilers on the market, with a noise level of 44dB. 


  • Large digital display
  • Compact cupboard fit, discrete install
  • Compatible with Ideal controls
  • Hard-wearing and scratch-resistant
  • Ease of commissioning and service
  • Easy to install (Low lift weight) & easy to use
  • Service timer with telephone number display/service display
  • Up to 10-year warranty 

Glow-worm Energy 12S


The Glow-worm Energy System boiler is a light and compact boiler with a choice of rear or top flue making it easy to install in any situation. The automotive-grade aluminium heat exchanger has large waterways making it perfect for retrofit jobs. This system boiler range has five kW outputs, all with different dB levels. The Glow-worm Energy 12S is the quietest of the range, with a dB level of 45.


  • Quiet operation
  • Top and rear flue options
  • High-quality automotive-grade aluminium heat exchanger
  • Compact cupboard fit
  • Modern bright LCD display
  • High efficiency modulating Grundfos pump 
  • Easy to use controls 

Vaillant EcoTec Plus 630

Vaillant Ecotec Plus (Heat Only) Boiler

The Vaillant ecoTEC plus range of system boilers is available in a wide range of output models including 12kW, 15kW, 18kW, 24kW, 30kW and 37kW, meaning that there is a kW output option available for everyone. The stylish design and small dimensions also make it a perfect fit with any home. The Vaillant EcoTec Plus 630 has the lowest dB of the range, with a noise level of 48, which is ideal for families that require a higher demand for instant hot water. 


  • Removable side panels – For additional accessibility flexibility
  • Highly efficient and economical to run
  • Advanced modulation during periods of low heat demand
  • Flame lift detection system enabling more efficient and quieter combustion
  • Quiet Mark accredited
  • Stylish contoured case design with drop-down flap
  • Dedicated models available for LPG 
  • Step by step full text installation wizard

Vokera Vision S


The Vokera Vision System boiler is a compact and lightweight system boiler that can be installed neatly inside a standard kitchen cupboard. This system boiler range has been endorsed by the Energy Saving Trust, awarded for being a highly efficient and reliable system boiler. Although this system boiler has a noise level of 50dB, reaching the higher end of the safety scale, you can be sure that this system boiler won’t let you down. 


  • Lightweight and compact
  • Ideal for properties with up to 2+ bathrooms
  • Optional pipe cover provides a neat finish
  • Easy installation
  • OpenTherm inside 
  • Rear Flue
  • Easy to use controls 
  • Easy to read display screen 
  • Anti-cycle control
  • Auto temperature control

System boiler comparison table

MakeWorcester Bosch  Ideal Glow-Worm  Vaillant Vokera
ModelGreenstar 4000Logic MaxEnergy 12S EcoTec Plus 630Vision S 
dB Scaling4244454850

Top 5 quietest regular boilers

Ideal Logic Max Heat


If you are familiar with a regular or heat only boiler as many call it, then you will also know they require a lot of space in order to supply your home with hot water and central heating. However, your regular boiler doesn’t have to be large and in charge as well as loud. The Ideal Logic Max Heat range proves this! 

The Ideal Logic Max Heat 12kW has a dB level of only 36! However, unless your home has under 8 radiators, this model may not be suitable. With this said, its most powerful boiler, the 30kW, has a noise level of only 49dB, which is still within the safety levels. 


  • Compatible with Ideal Controls 
  • Compact and lightweight 
  • Hard-wearing and scratch-resistant casing 
  • Easy to use controls 
  • Up to 10 years warranty
  • Easy to reach pressure gauge 
  • Large LED display screen 

Baxi 600 Heat


The Baxi 600 Heat range is available in as a 13kW, 16kW, 19kW, 25kW and a 30kW, so there is an option for everyone. This regular boiler is ideal for homes with between 8 radiators and 20, and between 1-3 bathrooms.

Regular boilers are ideal for homes with a high demand for instant hot water, but you do need to consider the additional space you will need in your home for the hot and cold water tanks needed. If space is not an issue in your home, are you’re looking for a regular boiler with noise levels between 37dB and 49dB, this regular boiler may be a perfect choice for you! 


  • Top and in case rear flue
  • No pump overrun needed
  • Wall mounting plate
  • Front and side access for easy installation and service
  • Choice of flue lengths
  • Boiler Plus compliant
  • Easy to use controls 
  • Easy to read display screen

Viessmann Vitodens 100-W Open Vent

vitodens 100-w

The Viessmann Vitodens 100-W is not only easy to set up and easy to use, but it is also extremely quiet, with a noise level of only 39dB across the range, which is quieter than your average fridge! 


  • Compact and lightweight 
  • Available in LPG
  • Standard efficiency up to 97% through stainless steel Inox-Radial heat exchanger
  • Large display screen
  • Weather compensation option
  • Built-in frost protection
  • Efficient and durable 
  • Inox-Radial heat exchanger

Ideal Mexico HE

Ideal Mexico-HE

Providing excellent efficiency, the Ideal Mexico HE floor standing boiler offers low running costs and minimal maintenance.  With a compact floor standing design, frost protection and Energy Saving Trust endorsement, this model offers exceptional quality, value and efficiency. The perfect solution for replacements, the Mexico HE boiler benefits from a digital display, an optional remote user kit and a 2 year warranty. This regular boiler also has a noise level of only 40dB, making it one of the quietest regular boilers on the market. 


  • Compact floor-standing design 
  • Optional remote user kit
  • Energy Saving Trust endorsed
  • Range of outputs available
  • A user-friendly status display featuring temperature control and diagnostics

Worcester Bosch Greenstar Ri

Worcester 27RI and 30RI

Designed with the customer in mind, of course, the well-loved brand, Worcester Bosch, has designed a range that is perfect for those that are looking for a highly reliable yet quiet regular boiler. The Greenstar Ri is Worcester Bosch’s best selling regular boiler which is available in outputs of between 9kW and 30kW. When it comes to noise levels, the 9kW to 24kW have dB levels of 45, which is well within the safety limits. The Greenstar Ri 27kW and 30kW have a dB level of 52. 


  • Compact and wall-mountable 
  • Simple and easy to use controls 
  • Built-in frost protection
  • Can be used with Greenskies solar panels for energy and cost savings
  • Suitable for homes where the heating system includes a hot water storage cylinder
  • 10-year warranty with WarmZilla
  • Durable and reliable

Regular boiler comparison table

MakeIdealBaxi ViessmannIdeal Worcester Bosch
ModelLogic Max Heat 12kW613 Heat Vitodens 100-W Open VentMexico HEGreenstar Ri (9kW-24kW)
dB Scaling3637394045

It is important to consider the dB scaling when purchasing your new or replacement boiler, however, there could be a few reasons why your existing boiler is making strange noises, which we will cover next. Inspecting and fixing these points could potentially prevent you from having to buy a new or replacement boiler.

Why is my boiler making noises?

There are a few reasons why your boiler could be making strange noises. It is important to get this looked at by your Gas Safe engineer, as this can be a sign of serious problems. We have a blog that goes more into depth about why your boiler could be making strange noises. If you are experiencing banging, whistling, gurgling, whooshing, or any other strange noises from your boiler then this article will help you to identify the noise and what may be causing it.

Clunking and banging noises

Noises such as “kettling” are caused when limescale is accumulated in the heat exchanger. This will block the flow of water and cause it to boil, steam, and expand, resulting in your boiler making loud banging noises.

Whistling noises

This may be caused by a loss of water pressure or blockage. It could also be caused by trapped air. Boiler repair in this case will be relatively simple and will simply include the release of trapped air.

Gurgling noises

This can be caused by a frozen condensate pipe. This can be resolved by defrosting the pipe. We have this covered in another blog. If you are interested in more information on How to unfreeze your condensate pipe, take a look at how easy it is to resolve.

It is important not to attempt to touch any part of your boiler or central heating system if you’re unsure about what you’re doing. It is recommended that you seek advice from a qualified gas-safe heating engineer if you are experiencing any of the above issues. 

If you’re unsure about what boiler is best suited to your home, we have a few blogs that may be able to help: 

Or like we said, you could check out our Boiler Comparison tool, which allows you to compare your current boiler against other boiler models or brands, or compare up to three new boilers at once to help you find the perfect new boiler for your home. 

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