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Nationwide next day installation
Worcester Bosch Greenstar 4000 25KW Combi Boiler
POPULAR
10-year warranty
Free wireless thermostat
Stylish, reliable and remarkably quiet
Great for small to medium-sized homes, the Greenstar 4000 is a super quiet boiler - packed with the latest energy-saving technology while delivering reliable heating and hot water solutions quietly.
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Our view
You can never go far wrong with a Worcester Bosch combi and the Greenstar 4000 25KW is no exception. This replacement for its much-celebrated predecessor, the Greenstar 25i, is definitely an upgrade. It is stylish, quiet, easy to use and has a wide power range.
When you choose dwellow to install this A-rated boiler, you'll receive a 10-year warranty and our 12-month workmanship cover for peace of mind.
We like this boiler and we have written an in-depth review of it's big brother, the Worcester Bosch Greenstar 4000 30KW, which shares many of the same features if you wish to find out more.
Key features
Why choose the Greenstar 4000?
1
Quiet Mark Accreditation
The Greenstar 4000 is a reliable boiler that will operate with minimal fuss. This means this boiler is extremely quiet, producing only 45dB of noise, which will be no more noticeable than your fridge.
2
Efficient
This boiler has all the latest energy saving technology to help lower your gas bills. This boiler can adjust its power to 10% of its output for maximum efficiency, a feature known as modulating, so you only use as much power as is needed at the time. It also has a quick tap function to save water and reduce waste (some water is heated ready to use straight away, so you don't have to run the water to several minutes waiting for it to get hot)
3
Ease of use
The Greenstar 4000 range is easy to programme with a full colour display panel. All combi boilers that dwellow sells come with a free wireless thermostat, or you can upgrade to a smart thermostat or reconnect your existing controls at checkout.
Frequently asked questions
Here are answers to questions we're often asked, but if you're unsure or want to know more just give us a call.
Do you install in my area?
Yes. We install right across the UK and where we can we have installation dates available next day (for orders placed before 12pm). Our online quote tool takes a couple of minutes and you'll be able to see all of our availability right from the tool. Go ahead and get a fixed price quote.
Are your prices really fixed?
Yes they are.
When using our fixed price quote tool we need you to be as accurate as you can, but don't worry there are no tricky questions. If it looks like your boiler might be in a hard to access location we'll ask to give you a call before we firm up the quote - but for most people we won't need to do that.
All our new boiler installations include a chemical flush to ensure your system is clean. We also provide new heating controls when necessary, along with a new flue and filter. If any upgrades are required for your pipework to meet the latest safety standards, we'll take care of that too.
When using our fixed price quote tool we need you to be as accurate as you can, but don't worry there are no tricky questions. If it looks like your boiler might be in a hard to access location we'll ask to give you a call before we firm up the quote - but for most people we won't need to do that.
All our new boiler installations include a chemical flush to ensure your system is clean. We also provide new heating controls when necessary, along with a new flue and filter. If any upgrades are required for your pipework to meet the latest safety standards, we'll take care of that too.
What happens if I need to change my installation date?
Please give us a call, and our friendly team will be happy to change your installation date.
What time will my Engineer arrive on the day of my installation?
Your engineer will arrive between 08:00-10:00. Your engineer will call you on route with an expected arrival time. At around 09:30-10:00, you will receive a call from our audit team confirming the safe arrival of your engineer, boiler, and materials. Your engineer will also carry out a pre-installation walk-through, setting accurate expectations before commencing with your installation.
How will I know my engineer has completed the work to the required standards?
Our engineer will take photographs throughout the installation, allowing us to review the quality of the work before signing off on the installation. Once our engineer has completed your installation and left your home, you will receive a call from our in-house audit team. They will ask you a few post-installation questions and confirm your satisfaction with your installation. This post-audit process is carried out on 100% of our installations, ensuring the highest service standards and giving our customers total peace of mind.
Will the Engineer leave my home clean and tidy?
After the installation, our engineers take pride in leaving your home in the same clean and tidy condition as they found it. They will dispose of your old boiler, pipework, and packaging, ensuring you can enjoy your new installation without any hassle.
Make
Worcester Bosch
Model
Greenstar 4000 25KW Combi Boiler
Efficiency rating
94%
Efficiency band
A-rated
Central heating max. output
24KW
Hot water max. output
25KW
Mounting
Wall mounted
Flow rate
10.2 litres/minute
Manufacturers warranty
10-years
Height
724mm
Width
400mm
Depth
310mm
Flow rate: 10.2l/min
Radiators: up to 10 radiators
Free magnetic filter
What's included?
Like you we don't like surprises when it comes to heating. Our fixed price packages come with everything you need
Boiler and installation
Your new boiler
Installation by a gas safe registered installer
Pipework, including upgrades
Pipework required to ensure your new boiler fits perfectly
Condensate pipework if not already installed
Upgrade of your gas pipe (up to 22mm) if required
New exhaust flue
A new flue, either horizontal or vertical, to fit with where the boiler is installed
Any brickwork required if the boiler is moved to a new location
Chemical flush, water treatment and filter
Chemical flush of your home's existing pipework and radiators to remove debris that has built up over time.
Inhibitors to protect your central heating system and new boiler from corrosion and limescale.
New filter that captures magnetic debris in your system and extends the life of your new boiler
Thermostat and upgrades
Free wireless thermostat on all combi boilers. If you'd prefer we'll also reconnect your existing smart controls
Fitting of any upgrades you select at the checkout, including smart controls
Warranty and after care
We register your manufacturers warranty which includes all parts and labour on your boiler and flue
12-month workmanship warranty
Gas Safe certificate and building control notifications
What's not included
Asbestos removal if we find this at your property
Scaffolding or specialist access equipment
Looking for a different Worcester Bosch model?
Boiler buying, made simple
Answer a few simple questions and get a fixed price quote with next day installation
You answer
No complicated questions. With your answers and our know-how, we figure out the right package for your home
Pick a package
All our packages include everything you need, all for a fixed, transparent price, including installation and warranty.
Choose a date
We use local engineers who are vetted and gas safe registered. They'll arrive between 8am and 10am on the day.
Relax, we've got you sorted
We install boilers from top manufacturers like Viessmann and Worcester Bosch, meaning you'll benefit from warranties up to 10-years.
Gas safe
Your new boiler will be installed by a local, friendly, installer. You'll be up and running in no time.
Next day installs
Order before 12pm and we could be fitting your boiler the next day. Our installers have fitted over 15,000 boilers nationwide.
Help on hand
Need a bit of advice? Our friendy team are just a call away. We'll have you sorted in no time.
Energy savings
All our new boilers are super efficient. You could save up to £475 a year on your gas bills.1
Buy a new boiler
From city flats to country homes we fit boilers of all shapes and sizes
Combi
Ideal for small and medium sized homes including flats
Features
Heat water on demand
Space saving, no tank needed
Easy installation with just one unit needed
Regular
Typically found in older homes with high hot water demand
Features
Older heating system
You'll have a tank in the loft and a cylinder
Supports high water demand
System
Great for larger homes with good mains water pressure
Features
Ideal for larger homes with lots of hot water demand
No tank in the roof
Compatible with solar panels
Let’s have a chat
If you're not sure where to start? One of our friendly team are on hand
Answers to
Frequently Asked Questions
The most common questions we get asked about new boilers.
View all
Do you install in my area?
Yes. We install right across the UK and where we can we have installation dates available next day (for orders placed before 12pm). Our online quote tool takes a couple of minutes and you'll be able to see all of our availability right from the tool. Go ahead and get a fixed price quote.
Are your prices really fixed?
Yes they are.
When using our fixed price quote tool we need you to be as accurate as you can, but don't worry there are no tricky questions. If it looks like your boiler might be in a hard to access location we'll ask to give you a call before we firm up the quote - but for most people we won't need to do that.
All of our new boiler installations come with a chemical flush (to make sure your system is nice and clean) plus we also include new heating controls when they are needed, a new flue, filter and if there are any upgrades needed to your pipework to bring them up to the latest safety standards, we'll also cover that.
When using our fixed price quote tool we need you to be as accurate as you can, but don't worry there are no tricky questions. If it looks like your boiler might be in a hard to access location we'll ask to give you a call before we firm up the quote - but for most people we won't need to do that.
All of our new boiler installations come with a chemical flush (to make sure your system is nice and clean) plus we also include new heating controls when they are needed, a new flue, filter and if there are any upgrades needed to your pipework to bring them up to the latest safety standards, we'll also cover that.
Who are dwellow?
We are on a mission to make energy savings simple. Our team have over 90-years of experience in the home energy market in the UK - having pioneered buying a boiler online.
Our installers are all gas safe registered and local to you - so you'll be supporting local people who take real pride in their work.
Our installers are all gas safe registered and local to you - so you'll be supporting local people who take real pride in their work.
Who are your installers?
All of our installers are Gas Safe registered and local to you. They have all been checked and their qualifications verified before joining our installation partners. This includes ensuring they have the right experience and insurance in place.
We're proud of the quality of our work and so all of our boiler installations come with a 12-month workmanship warranty, free of charge. We'll take care of your home and if anything goes wrong we are here to help.
We're proud of the quality of our work and so all of our boiler installations come with a 12-month workmanship warranty, free of charge. We'll take care of your home and if anything goes wrong we are here to help.
How much does a boiler cost to replace?
Our online fixed price quote tool will give you a price in under two minutes which is specific to what you need for your home. We realise upgrading your boiler is an investment so we have worked really hard to keep our costs down to make sure you get a low and fair price for a quality installation.
Also have a look at our guides as we regularly publish our views on the best new boilers, what to look for and how much you should expect to pay.
Also have a look at our guides as we regularly publish our views on the best new boilers, what to look for and how much you should expect to pay.
Get in Touch
Hermes House, Fire Fly Avenue, Swindon, Wiltshire, SN2 2GA
hello@dwellow.co.uk
0330 822 2795
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