Worcester Bosch vs Viessmann Boilers
Choosing between boiler brands need not be difficult when you have access to in-depth information.
By comparing similar boiler models across different brands, you can have a better idea of which combi boiler will work most effectively in your home and suit your budget.
In this guide, we discuss:
- who is Worcester Bosch?
- who is Viessmann?
- which types of boilers do Worcester Bosch and Viessmann manufacture?
- Worcester Bosch and Viessmann: head-to-head
- Worcester Bosch Greenstar 12Ri Boiler review
- Viessmann ecoTEC plus 825 Boiler review
- which manufacturer wins the battle of the flagship boilers?
- Worcester Bosch boilers: an overview
- Viessmann boilers: an overview
- repairs and warranties
- how to get new boiler installation quotes
Who is Worcester Bosch?
Worcester Bosch is a British manufacturer of boilers and heating products with a factory located in Warndon.
The company was founded as Worcester Engineering Co Ltd in 1962 before being acquired by Robert Bosch in 1992.
Following acquisition, the group changed its name to the Worcester Bosch brand as we know it today.
They are committed to environmental sustainability and their working practices adhere to a strict and comprehensive sustainability policy.
They’re also the company behind the Robert Bosch Foundation which has spent over £757 million on improving social initiatives.
They employ over 2,000 people across the UK and they have a substantial network of over 300 service engineers and over 80 sales managers.
Who is Viessmann?
Viessmann is a German manufacturer of boilers, heating, and cooling solutions founded in 1917 by Johann Viessmann.
They are a family-led company to this day and, although they produce many leading boilers internationally, the company has recently expanded their focus to creating and maintaining ‘living spaces’ for people.
Viessmann operate an academy to train and accredit heating engineers in Germany, the UK, and further afield and they educate over 92,000 industry specialists annually.
What types of boilers do Worcester Bosch and Viessmann manufacture?
Worcester Bosch designs and manufactures a large range of oil and gas combi boilers, regular boilers, and system boilers.
In each of the three option ranges from Worcester Bosch, they offer customers a choice of outputs, budgets and different model specifications.
Viessmann are one of the leading international manufacturers of domestic and commercial boilers.
Like Worcester Bosch, they design and manufacture an extensive range of gas combi boilers, oil boilers, commercial steam boilers and much more.
Alongside their range of boilers, they also offer heat pumps and combined heat and power solutions like solar panels.
Combi boilers
Combi boilers are an ever-popular choice for many households due to their levels of energy efficiency, compact size, and cheaper running costs.
They work by heating the water directly from your mains supply in the boiler itself so that, as soon as you turn the hot taps on, heated water will almost instantly be available to you and never runs out.
They are energy efficient because they make good use of the power they need to heat the water for your taps and radiators.
Very little energy is wasted by a combi boiler so that your annual heating bill is generally much lower.
Because there are a lot of different power outputs available in combi boilers, you can find a suitable model for almost any size of home.
Regular boilers
Regular boilers, otherwise known as traditional boilers, are better suited to larger properties which need lots of hot water with no decrease in water pressure.
They require a storage tank of cold water in your loft which feeds water through to the boiler to be heated.
Once the water is heated, you have a supply of hot water that lasts until it runs out and you need to wait for it to reheat once more.
Regular boilers are often installed in properties that have the pipework already set up for this system.
System boilers
A system boiler can be a good choice for a larger home which doesn’t have room for a storage tank in the loft as the water is held internally within the hot water cylinder itself.
It heats the water up from the mains and stores it which means you don’t lose water pressure if more than one person is using the hot water at one time.
However, as with regular boilers, once it runs out you need to wait for more to heat up.
Worcester Bosch and Viessmann head-to-head
In the UK today there’s a huge choice of boiler brands and models available, which can make it a daunting challenge to many.
We want to help you make an informed decision when choosing the most suitable combi boiler for their home size and water requirements.
This is why we’ve designed our own unique boiler rating system that ranks boilers according to their price, output level, energy efficiency level, and warranty included.
Deciding on a suitable combi boiler choice for your home is much easier when you have in-depth metrics to compare and contrast.
The following table is a general comparison of the two brands across their entire range which gives you an overview before we take a more detailed look at specific Worcester Bosch and Viessmann models.
| Manufacturer | Average price | Energy efficiency | HomeSage score |
| Worcester Bosch | £1,391 | 93.39% | 90.25% |
| Viessmann | £1,467 | 89.17% | 77.91% |
As you can see, Worcester Bosch manufactures slightly cheaper boilers on average which have a higher energy efficiency level – resulting in a higher overall score on our HomeSage boiler ranking scale.
To give you a broader understanding of boilers available in these ranges, we’ve compared the top two scoring HomeSage-rated gas-powered combi boilers from each manufacturer.
These are:
- Worcester Bosch Greenstar 12Ri Boiler
- Viessmann ecoTEC plus 825 Boiler
Both of these boilers have an ideal output rate for smaller houses and flats.
Worcester Bosch Greenstar 12Ri Boiler review
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Worcester Bosch Greenstar 12Ri Boiler | 92.00% | 60 | 12 | £800 | 79.57% |
The Worcester Bosch Greenstar 12Ri is a compact and modern boiler that features dimensions of 600mm x 390mm x 270mm, user-friendly control knobs and a simple, clear display.
It is an environmentally friendly option as it produces a low amount of NOx and CO2 emissions alongside a high energy efficiency rating of 92%.
The internal components are made from cast aluminium and silicon so there is a minimal amount of energy wasted through the boiler flue pipe resulting in lower heating bills for you.
This boiler can be easily set to your favourite heating choices and adjusted quickly for maximum comfort and cosiness.
It comes complete with a 10-year warranty providing you keep up to date with annual services undertaken by accredited Worcester Bosch engineers.
Viessmann B1KC Vitodens 100-W 30kw Boiler review
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Viessmann B1KC Vitodens 100-W 30kw Boiler | 88.39% | 60 | 30 | £1,080 | 78.99% |
The Viessmann B1KC Vitodens 100-W 30kw is slightly lower in energy efficiency, scoring a ‘B’ on the SEDBUK scale, and it is just over 88% efficient.
The dimensions of this boiler are 700mm x 400mm x 350mm and it features a front-access panel for easy installation and maintenance.
It comes complete with a 5-year standard warranty on the boiler however the internal Inox-Radial Heat exchanger has a warranty of 10-years.
The heat exchanger has excellent corrosion resistance and is self-cleaning, so you don’t need to worry about potential blockages or build-up of dirt.
Who wins the battle of the flagship boilers?
As you can see, Worcester Bosch comes in first place with a higher overall score due to their energy efficiency levels, price and length of warranty.
Although the two models we compared have different output levels, the comparative price and length of warranty resulted in the Worcester Bosch achieving a higher total HomeSage score.
The Viessmann boiler had a lower energy efficiency rating with 88%, meaning 12% energy would be lost compared to 8% lost energy with the Worcester Bosch model.
The Worcester Bosch was also considerably cheaper though, as noted, it is a smaller output and the price would be higher if you required a more powerful combi boiler.
Worcester Bosch gas combi boilers
Worcester Bosch has a range of 49 gas-powered boilers in their range at time of writing.
The average price of one is approximately £1,391 which is applicable to the whole range of combi, system or regular boilers.
Worcester Bosch top 5 gas combi boilers
Of the 21 gas-powered combi boilers in Worcester Bosh’s range, the top 5 scoring models are:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Worcester Bosch 2000 25kw Boiler | 93.00% | 60 | 9 | £760 | 91.89% |
| Worcester Bosch 2000 30kw Boiler | 93.00% | 60 | 10.8 | £870 | 91.62% |
| Worcester Bosch Greenstar 25i Boiler | 94.00% | 60 | 9 | £955 | 91.41% |
| Worcester Bosch Greenstar 28CDi Compact Boiler | 94.00% | 60 | 10 | £980 | 91.35% |
| Worcester Bosch Greenstar 25Si Compact Boiler | 94.00% | 60 | 8.9 | £1,055 | 91.16% |
Worcester Bosch top 5 regular gas boilers
At the time of writing this report, Worcester Bosh have 14 gas-powered regular boilers in their range, boasting an average HomeSage rating of 90.44%.
The top 5 are as follows:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Worcester Bosch Greenstar 12Ri Boiler | 92.00% | 60 | 12 | £800 | 91.79% |
| Worcester Bosch Greenstar 15Ri Boiler | 92.00% | 60 | 15 | £825 | 91.72% |
| Worcester Bosch Greenstar 18Ri Boiler | 92.00% | 60 | 18 | £880 | 91.59% |
| Worcester Bosch Greenstar 24Ri Boiler | 92.00% | 60 | 24 | £935 | 91.45% |
| Worcester Bosch Greenstar 21Ri Boiler | 92.00% | 60 | 21 | £975 | 91.36% |
Worcester Bosch top 5 gas system boilers
All of the top 5 scored gas-powered system boilers in Worcester Bosch’s range are from the renowned Greenstar Ri range.
The HomeSage top 5 are as follows:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Worcester Bosch Greenstar 9i Boiler | 93.00% | 60 | 9.2 | £880 | 91.59% |
| Worcester Bosch Greenstar 12i Boiler | 94.00% | 60 | 12.2 | £890 | 91.57% |
| Worcester Bosch Greenstar 15i Boiler | 94.00% | 60 | 15.3 | £950 | 91.42% |
| Worcester Bosch Greenstar 18i Boiler | 94.00% | 60 | 18.4 | £1,005 | 91.29% |
| Worcester Bosch Greenstar 21i Boiler | 94.00% | 60 | 21.6 | £1,015 | 91.26% |
Viessmann gas combi boilers
Viessmann’s range of gas-powered boilers currently stands at 28 models and has an average price of £1,467.
Here we list the top models in their ranges of combi, regular and system boilers.
Viessmann top 5 combi boilers
Viessmann has 15 gas-powered system boilers in their range, with an average HomeSage rating of 76.98%.
The top 5 are:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Viessmann B1KC Vitodens 100-W 30kw Boiler | 88.90% | 60 | 30 | £1,075 | 79.01% |
| Viessmann B1KC Vitodens 100-W 26kw Boiler | 89.10% | 60 | 26 | £1,105 | 78.93% |
| Viessmann B1KC Vitodens 100-W 35kw Boiler | 89.30% | 60 | 35 | £1,150 | 78.82% |
| Viessmann B2KB Vitodens 200-W 35kw Boiler | 89.10% | 60 | 35 | £1,395 | 78.22% |
| Viessmann B2KB Vitodens 200-W 26kw Boiler | 89.00% | 60 | 26 | £1,415 | 78.17% |
Viessmann top 5 regular boilers
In Viessmann’s regular boiler range, there are 5 available with an average price tag of £949.
The average score on our HomeSage boiler scale is 79.37% and the results are as follows:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Viessmann WB1B Vitodens 100-W 13kw Boiler | 89.00% | 60 | 13 | £830 | 79.61% |
| Viessmann WB1B Vitodens 100-W 26kw Boiler | 89.30% | 60 | 26 | £880 | 79.49% |
| Viessmann WB1B Vitodens 100-W 16kw Boiler | 89.10% | 60 | 16 | £880 | 79.49% |
| Viessmann WB1B Vitodens 100-W 19kw Boiler | 89.00% | 60 | 19 | £880 | 79.49% |
| Viessmann WB1B Vitodens 100-W 35kw Boiler | 88.70% | 60 | 35 | £1,175 | 78.76% |
Viessmann top 5 system boilers
Viessmann currently have 8 different models of system boilers, with an average price tag of £1,209 and a 78.74% average HomeSage score.
The best scoring boilers in this range are as follows:
| Make and Model Name | Efficiency Rating | Parts and Labour Warranty | Output kW | Price from | TOTAL |
| Viessmann B1HC Vitodens 100-W 26 Boiler | 89.40% | 60 | 26 | £975 | 79.25% |
| Viessmann B1HC Vitodens 100-W 19 Boiler | 89.20% | 60 | 19 | £975 | 79.25% |
| Viessmann B1HC Vitodens 100-W 30 Boiler | 89.00% | 60 | 30 | £1,080 | 78.99% |
| Viessmann B1HC Vitodens 100-W 35 Boiler | 89.40% | 60 | 35 | £1,150 | 78.82% |
| Viessmann B2HB Vitodens 200-W 19 Boiler | 89.00% | 60 | 19 | £1,225 | 78.64% |
Non-gas powered boilers
Viessmann only manufactures gas boilers and, similarly, Worcester Bosch also focuses most of their attention on the gas boiler market.
However, Worcester Bosch do have a range of oil-based boilers.
The average cost of an oil-powered Worcester Bosch boiler as of July 2020 is £2,309 and there are 18 different models to choose from with an average HomeSage score of 81.36%.
Oil-fuelled boilers are an option for homeowners or renters whose property is not connected to the mains gas grid.
They require a storage tank of fuel on your property and regular topping up by your fuel provider.
Oil boilers are cheaper to run than electricity-powered boilers so it’s an option certainly worth considering if you don’t have connection to the UK gas network.
The disadvantages of using an oil boiler are that they are expensive to fit especially if you don’t have the correct pipework already set up.
You need to be aware of your fuel levels so you don’t run out.
Also, if there is a problem with bad weather or roadworks getting to your property you may have to survive without until there is clear access.
Repairs and warranties – how do both companies compare?
Boilers all come with manufacturer-backed warranties although the amount of time can vary considerably from 1 year to 10 years.
Most boiler guarantees or warranties will require you to have an annual boiler service usually undertaken by a company-accredited Gas Safe engineer otherwise you risk losing the cover provided by the warranty.
Some boilers have separate warranties or guarantees for the internal components which is useful if they break down further down the line.
Get new boiler installation quotes
If you are researching the financial implications of a new boiler, you’ll be aware that it can be a costly exercise if you don’t do your research properly.
As well as the price of the new boiler itself, you also have to pay for installation which will add to your overall bill.
This may include re-doing pipework or completely refiguring your plumbing system if you are changing the type of boiler you have.
Choosing the right model and make of boiler is simply the first step in the process.
The safest way to find the best boiler for your property size and requirements is to speak with a selection of registered Gas Safe engineers.
By doing this, you can make sure you are getting a fair price for the product and service you want.
Speaking with an accredited engineer means you can get a quote based on your requirements and a rough estimation of how much money you will save per year.
We can help you do this without the need for you ringing around a variety of companies.
Simply fill out the form on this page and we get in contact with 3 or 4 local, reliable and Gas Safe Engineers in your area who will then contact you directly with their quotes.
You can then decide what you want to do – and it’s completely free for you and no obligation.
