Worcester 25i Combi Boiler REVIEW and Buying Guide 
Up until 2021, Worcester 25i was Worcester’s flagship boiler. And even after its replacement by the Greenstar 4000 range, the 25i is still highly relevant — and available.
If you’re thinking about getting a Greenstar 25i combi gas boiler, you’re in the right place. In this review, we will walk you through the boiler’s features, installation costs, and alternatives. Read on to find out more!
Greenstar 25i Features
Below, we will review the most essential features of the 25i range.
Frozen Condensate Pipes & Pumps
One of the main reasons we are called out to fix boilers, relates to frozen condensate pumps and pipes. When residue freezes, and blocks these components, the boiler will lock out and stop working.
The Worcester 25i now incorporates a CondenseSure Siphon. This acts as a preventative measure for condensate freezes.
This not only means you’ll have fewer problems in the winter months, but you’ll also be saving money on expensive engineer call out charges.
Boiler Display Panel
A big gripe for owners of the 24i Junior was the lack of functionality (and complexity) of the display panel. It was ugly, hard to use, and didn’t help users fix the simplest of problems.
Fortunately, the Worcester 25i now has increased functionality. Users can now adjust the hot water and heating temperature on the panel without the use of a thermostat.
And that isn’t all, when there is a problem with the boiler, it will display the relevant fault code which makes a fault much easier to diagnose and fix for an engineer.
Increased Hot Water Output
Worcester are always trying to increase the hot water output on all their boilers. So, the Worcester 25i combi now has 25kW of output, up from its original 24kW.
Like all the Worcester range, the 25i comes with a basic 5-year warranty. This can be increased by 1 year, by adding a magnetic system filter. It’s important to note that the filter must be a Worcester Bosch branded filter to get this extra warranty.
Heatable are one of the biggest installation companies fitting Worcester boilers. You can get a fixed price on screen for a Worcester 25i with a 10-year warranty here.
One of the most popular new controls that can be used in conjunction with the 25i is the Worcester Wave. It’s a smart, Wi-Fi powered, heating control. It means you can set and change your heating using their Wave app.
This can cost upwards of £180, so ask an engineer for suitable alternatives if you don’t require Wi-Fi based stats and timers.
A Word on Worcester Bosch Servicing
Many installers will mention that the Worcester range is not just more difficult to install than other brands, but also to service. As a property owner, that means that installation and servicing costs increase.
This is something that Worcester have worked on for both the 25i and 30i, and the main components are much easier to access.
Alongside this, the control panel offers a lot more details when it comes to boiler faults, meaning an engineer can usually diagnose problems over the phone (saving you expensive call out fees).
What Size Combi Do You Need?
Before you go any further, it’s important to understand whether this is the right sized boiler for your property. The 25i is suitable for properties up to 3 bedrooms, if they have low demand for hot water and heating.
Not sure if it’s right for you?
You can use this boiler size calculator to find boilers with the optimum heating output and hot water flow rate for your home.
The most suitable properties are likely to have no more than 1 shower, and only 2 bedrooms. This includes small apartments, flats and 2-bedroom terraced houses.
If you have a property with 2 or more showers, more than 10 radiators, or more than 3 bedrooms, you’ll need something much bigger. In fact, combi boilers aren’t ideal for large properties with high water demand, so you may need to consider a different boiler type altogether.
If you are looking for a boiler that’s the next step up from the 25i, checkout our review of the Worcester 30i here. And, if that’s not enough, we usually recommend checking out the Vogue C40 from Ideal Boilers.
Worcester Greenstar 25i Prices (Boiler + Installation)
So, the question is, how much does the Worcester 25i combi boiler cost? Typically with Worcester Bosch, you’re going to find their prices are up there with the more premium boiler brands on the market. You’ll be comparing them directly with the likes of Baxi and Vaillant.
From plumbing merchants, expect to see prices for the Worcester 25i, in the £950 region (inc VAT). That’s going to be a “boiler only” package. So, if you need a new flue, extensions and a timer, that’s all going to come at an additional cost.
Worcester Greenstar 25i Installation Cost
So, how much is the Worcester 25i going to cost to install? With a £950 sale price, you should expect to pay somewhere in the region of £2,100 for an installation from a local Gas Safe engineer. Of course, the exact price depends on the materials they need, and the complexity of the install.
We’ve recently come across a cheaper way to get Worcester boilers installed, including the 25i, and that’s with Heatable.
It goes without saying that Heatable are probably getting the 25i cheaper than any other installer in the country, for this very reason. And, that means you’re going to be able to save money when it comes to the cost of fitting the boiler.
Heatable have an online fixed price quotation system, which is pretty cool. It takes around 90 seconds.
Included in your quote from Heatable, you’ll get these 3 extras, too:
- A free Honey Well thermostat, RRP is £199.99
- An initial clean of the heating system, which is going to protect the boiler
- A heating filter — a long-term preventative measure to stop the boiler from getting blocked up with heating sludge. These are worth around £130.
But don’t take my word for it — you can get itemised quotes from up to 3 local boiler installers here.
Worcester 25i vs Worcester 25Si Compact
The Worcester Greenstar range doesn’t just consist of the i, but also the Si Compact range. Both boilers are combination boilers. So, how does the 25Si Compact differ?
The 25Si Compact is Designed for Small Installation Areas
The main reason people buy the 25Si Compact over the i, is size. For instance, if you were fitting a boiler in a kitchen cupboard, or under your stairs, it’s unlikely that the 25i will fit. The 25SI Compact has been designed with these small spaces in mind.
Compact Boilers Cost More
Although the prices of boilers change all the time, we find there is a constant in price differences. If you need a 25Si Compact, expect to pay around £95-105 more than the standard Worcester 25i.
Which is the Best Worcester Boiler?
The 25i and 25Si Compact are both excellent options, which should last a long time and save you money on energy bills if you’re upgrading from an old boiler. Both have reliable parts (like a quality heat exchanger), and boast a high energy efficiency rating.
The difference boils down to physical dimensions and price.
If you don’t need to install the boiler in a tight space, the 25i would be the obvious choice. The 25Si Compact really has little benefit in comparison, and costs more.
Obviously, if you need to fit the boiler in a tight space, you’ll be leaning towards the Compact.
Alternatives to The Worcester Greenstar 25i
There are a tonne of alternatives to the Worcester 25i.
First, let’s start with Ideal Boilers.
So, why do we recommend these boilers?
We rarely get any comeback after installing Ideal Boilers. On the flip side, the Ideal Logic Plus (7-year warranty) tends to be around 10% cheaper than any Worcester, and the Vogue (10-year warranty) is around the same price.
Other Worcester 25i alternatives worth researching are:
- Baxi Duo-Tec 24
- Vaillant Eco-Tec Pro 24 and the Vaillant Eco-Fit Pure 825
- Vokera Excel 24 (budget option and considered much lower quality)
- Potterton Gold 24
Worcester Greenstar 25i Review Verdict
Space is the first thing to consider. If you are restricted by space, and are 100% convinced you want a Worcester, the Worcester 25SI Compact is going to be your only option. However, if space is not an issue, then you’ll be looking at the Worcester 25i.
If you are more bothered about price and warranty, the Ideal Boiler range is an obvious choice. But, not so much so now you can get the 25i from Heatable at a similar price and with attractive finance options.
The Ideal Logic Plus 24 will save you around 10%, and you’ll get a 7-year warranty. If you’d prefer a higher warranty, the Ideal Vogue C26 will give you an extra 3 years.
Thanks for reading our review of the Worcester Greenstar 25i.
Is there anything we missed?
If we did, or if you’ve got a question, please leave us a comment below and we’ll get back to you as soon as we can.