Worcester Greenstar RI Boiler (REVIEW): 2023 Buying Guide

Worcester Bosch is one of the premier boiler manufacturers in the UK and the Greenstar RI range is perhaps its flagship model. But is it the right boiler for you?

In this review, we will tell you everything you need to know about the Worcester Bosch Greenstar RI Boiler Range to help you decide if it is what you are looking for.

When you are looking for a new boiler, it is quite likely that Worcester Bosch is a name you are considering. They make a lot of boilers but the Greenstar RI is perhaps their best-known and most reputable range.

Reputation alone is not enough to judge a good boiler on though. You need to know all of the details about how the boiler is made and how it works in order to be able to make an informed decision over whether it is what you are after.

In this guide, we will provide all the details you need to help you make the right decision. We will also show you where you can buy a Worcester Bosch Greenstar RI Boiler for less and save money on installation costs too.

So, if you are considering buying a boiler from the Worcester Bosch Greenstar RI range, this guide is essential reading for you.

Is a Regular Boiler right for you?

Before we dig any deeper into the details of the Worcester Bosch Greenstar RI boiler range, it is important that you decide from the start whether or not it is the right type of boiler for your property.

The Worcester Bosch Greenstar RI range is a selection of regular boilers. They are not combi boilers and this means they will need both a hot water cylinder and a cold feed in the loft.

If you already have a cylinder, you are able to keep it and the Worcester Bosch Greenstar RI range are terrific boilers to use with it. But if you don’t have a cylinder, you are more likely to want to buy a combi boiler such as the Worcester Bosch Greenstar i.

What’s in the Worcester Bosch RI Range?

The Worcester Bosch Greenstar RI range consists of seven different boilers. Each is a different size and designed to suit different sized properties:

The seven Worcester Bosch Greenstar RI boilers are:

  1. Worcester Bosch Greenstar 9Ri
  2. Worcester Bosch Greenstar 12R
  3. Worcester Bosch Greenstar 15Ri
  4. Worcester Bosch Greenstar 18Ri
  5. Worcester Bosch Greenstar 24Ri
  6. Worcester Bosch Greenstar 27Ri
  7. Worcester Bosch Greenstar 30Ri

If you want to do a quick comparison now to see which of these boilers sits within your budget, the quickest way to get a fixed-price quote for a Worcester Bosch boiler is on the WARMZILLA website.

Just hop over to their website now and spend a couple of minutes filling in their online to see how much the Worcester Bosch Greenstar range will set you back. You will be surprised at the reasonable prices and great deals that are on offer.

How big are the Worcester Bosch Greenstar RI boilers?

For a regular boiler, the Greenstar Ri range is actually surprisingly compact and this is true no matter which model you opt for.

All 7 boilers measure 600mm x 390mm x 270mm.

That’s really small and means they can all fit easily into a standard kitchen cupboard. This means you can tuck your boiler away in a kitchen or utility room where it doesn’t have to be on display.

Interestingly, Worcester Bosch has another boiler model designed as a compact model which is actually bigger than the Greenstar Ri boilers.

The Worcester Bosch CDI Compact measures 690mm x 390mm x 280mm. That makes it a full 80mm taller and 10mm deeper than the Greenstar Ri.

Central Heating Output

If you are wondering what the difference is between the different models in the Greenstar Ri range, it is mostly down to central heating output.

The numbers in the names of the different models is a simple indicator of what the different central heating outputs are:

  • Worcester Bosch Greenstar 9Ri: 9kw
  • Worcester Bosch Greenstar 12Ri: 12kw
  • Worcester Bosch Greenstar 15Ri: 15kw
  • Worcester Bosch Greenstar 18Ri: 18kw
  • Worcester Bosch Greenstar 24Ri: 24kw
  • Worcester Bosch Greenstar 27Ri: 27kw
  • Worcester Bosch Greenstar 30Ri: 30kw

The other main difference you will find is in the flow rate. For example, with the Worcester Bosch Greenstar 9Ri you will get 4.9 litres of water at a heat of 35°c. That is fine for a small property.

But the Greenstar 30Ri will give you 12.2 litres of water at a heat of 35°c which is a great deal more and necessary for larger homes.

Which model of Worcester Bosch Greenstar Ri Boiler do you need?

This really is the $64,000 question. It is difficult to say with any certainty what boiler size you need without first visiting your property to assess the size of the property and your hot water requirements.

The general rule of thumb is that the bigger the property and the more radiators you have, the larger boiler you will need.

If you don’t want to incur the cost of getting a qualified heating engineer out to assess your property and tell you what sized boiler to buy, the next best option is to run your details through WARMZILLA.

They boast a free Boiler-size calculator that will ask you a few simple questions and then tell you what the best sized boiler is likely to be for you. They will also give you a fixed-price quotation for a new boiler with a range of different providers and models including the Worcester Bosch Greenstar Ri.

How efficient is the Worcester Bosch Greenstar Ri boiler range?

The Worcester Bosch Greenstar Ri boiler range is A-rates. This means it is extremely energy efficient.

Using the Worcester Bosch Greenstar 24Ri as an example, you can expect a seasonal space heating efficiency of 92%.

It will also give you 86.7% efficiency when it’s working at full-tilt but if you drop it to 30% of capacity, this efficiency rises to a hugely impressive 97.2%.

This is great news for the environment but the question most customers will be asking is what impact it will have on your utility bills. The answer to that question will depend on the size of boiler you have and the state of your previous boiler, but regardless of those factors, the answer is likely to be that you will be making substantial savings.

To illustrate this, the Energy Saving Trust estimates that an average mid-terraced house that switches from a G-rated boiler to an A-rated model such as the Worcester Bosch Greenstar Ri could save as much as £315per year on their gas bill.

That is a substantial saving and it only covers your energy bills. When you factor in the costs of maintenance of an older boiler too, your savings are likely to be even higher.

When you think that you can buy a boiler on finance from a site like WARMZILLA for less than £20 a month, a new energy-efficient boiler can literally pay for itself.

How much will a Worcester Bosch Greenstar Ri boiler cost?

This is a question that is again tricky to answer because it involves factoring in a number of different things.

If you just want to switch one boiler for another without changing the type of boiler, you can expect to pay in the region of £1,700 for a new Worcester Bosch Greenstar Ri boiler. If you need a more powerful model, the price might be slightly higher.

If you want to change your boiler type from a regular boiler to a combi boiler, this will necessitate extra work which will push up costs. Likewise, if you need to move your boiler, fix pipework or radiators, or more, this will all cost money too.

Where To Get Installation Quotes For A Worcester Bosch Greenstar Ri boiler?

If you want to find out how much a new Worcester Bosch Greenstar Ri boiler will cost, the simplest thing to do is to get some quotes.

You have the option of getting a national installer, a local installer, or an online installer to do the work for you. It is good practice to get a quote from all three to compare the costs. Three quotes should be a minimum you get. If you can get more, do so.

In our experience, you are likely to find the national installer quote you the highest prices. Local installers have lower overheads so they will undercut these quotes a bit.

But the best prices you are likely to get are from online installers like WARMZILLA. They have all the benefits of a national operation without the overheads and that means they can pass on excellent savings to you.

They can often throw in a number of extras that other boiler installation companies cannot match. This includes things like a full system cleanse, a free filter (worth up to £130) that will help protect your new boiler, and an exclusive ten year warranty.

Getting a quote from WARMZILLA is easy, comes with no obligation, and doesn’t require you to hand over any personal information. Just fill in some basic details about your property and they will generate a fixed price quote with the best boilers to suit your property, including the appropriate Worcester Bosch Greenstar Ri boiler models.

Extra Winter Protection

Boilers are at their most vulnerable during the winter months but Worcester Bosch has its own way of protecting your boiler during the coldest time of the year; the Condensesure Siphon.

The Worcester Bosch Condensesure Siphon is intended to stop your boiler locking out if temperatures fall below freezing. When this does happen, it is usually because the condensing gases freeze as it is leaving your boiler.

This can stop your boiler working and necessitate calling out a heating engineer at considerable expense.

The Worcester Bosch Condensesure Siphon builds-up these condensed gases and then releasing them in batches. This means there is less chance of them freezing and causing you problems with your boiler locking up.

Worcester Bosch assures customers that their boilers can work for as long as 48 hours at temperatures as low as -15°C.

To achieve this, there are a couple of caveats. The pipework needs to be routed as close to vertically as possible, and 32mm piping needs to be used, rather than the standard 21.5mm pipes in most properties.

What warranties can I get on a Worcester Bosch Greenstar Ri boiler?

Our standard advice to all customers is to look for a minimum of a 5-year warranty on any boiler they are considering buying.

This is because the length of a warranty gives you a clear indication of how long a boiler is expected to last. The longer the warranty, the better the reliability of the boiler.

The good news is that if you buy a Worcester Bosch Greenstar Ri boiler through WARMZILLA, you will be eligible for their extended 10-year warranty offer. This brings great peace of mind and also clearly shows that you are spending money on a high-quality boiler.

Should You Buy A Worcester Bosch Greenstar Ri Boiler?

Ultimately, the decision about whether or not to buy a Worcester Bosch Greenstar Ri boiler is down to you. There are comparable boilers on the market from the likes of Vaillant, Viessmann, Baxi, and Ideal.

But the heating engineers we work with all recommend Worcester Bosch boilers extremely highly and the Greenstar Ri in particular.

Our research has also shown that it has everything you need from a high-end boiler yet is still available at competitively cheap prices.

The cheapest you will find a Worcester Bosch Greenstar Ri boiler is on the WARMZILLA website. Here you can get the price down to well below the comparable boilers from their rivals and benefit from perks like their extended ten year warranty.

This is great value for money and means that, if the Worcester Bosch Greenstar Ri boiler ticks all the boxes for you, we would certainly recommend buying one.


In this review, we have told you everything you need to know about the Worcester Bosch Greenstar Ri boiler range.

We have explained about the different models and helped you to figure out which size boiler you need. We have compared installation prices and told you about how to get special deals like the Worcester Bosch winter protection and an extended ten year warranty that is only available on WARMZILLA.

Above all, we have shown you how to save money when buying and installing a Worcester Bosch Greenstar Ri boiler, by using WARMZILLA.

Have you got a Worcester Bosch Greenstar Ri?

How has it worked for you? Any feedback for our readers? It is always useful to hear anecdotal stories about the products we review, especially ones like the Worcester Bosch Greenstar Ri boiler range that we rate so highly.

So, why not share your thoughts and reviews with us and our readers today. Just leave them in the comment box below.

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