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, we’ve got this covered, or even better, we have a Boiler Comparison tool that allows you to compare up to three boiler models or brands at one time, to help you find the ideal new boiler for your 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 fuelled 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 stored until you need it. Due to its large size, the regular boiler is not recommended for smaller homes with limited space.
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 30 dB to 60 dB, depending on the model and manufacturer.
So, now we know why it’s important to consider a boiler’s 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
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 30 kW, the Greenstar 2000 25 kW and 30 kW 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 26 kW 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 36 kW to suit a range of properties
Ideal Logic+ C35
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 24 kW and hot water output of 30 kW
- 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
| Make | Viessmann | Grant | Worcester Bosch | Ideal | Vaillant |
|---|---|---|---|---|---|
| Model | Vitodens 200 | Vortex Pro XS 26 | Greenstar 2000 (25+30) | Logic+ C35 | EcoTec Pro 30 |
| dB Scaling | 36 | 41 | 43 | 44 | 49 |