If you\u2019re comparing combi boilers for a flat or a smaller home, the Worcester Greenstar 25i will probably come up quickly. It\u2019s a well-known name, it\u2019s been around for years, and plenty of installers recommend it.<\/p>\n\n\n\n
But is it right for your<\/em> home? That depends on one thing most reviews skip: how much hot water your household uses at the same time. We\u2019ll cover that below, along with the specs, real pros and cons, and what you should expect to pay.<\/p>\n\n\n\n The Greenstar 25i is a solid, no-fuss combi boiler for homes with one bathroom<\/strong>. It\u2019s ErP A-rated, saves space because there\u2019s no hot water tank, and Worcester Bosch parts are easy to find. If two showers often run at once, or you have two bathrooms, you\u2019ll want something with a bigger hot water output.<\/p>\n\n\n\n Figures can differ slightly between model versions, so check the data sheet for the exact unit being fitted to your home.<\/em><\/p>\n\n\n\n The 25i is a combi, short for combination boiler. It does two jobs in one box: it heats your radiators and it heats water on demand straight from the mains.<\/p>\n\n\n\n That means no cylinder in the airing cupboard and no tank in the loft. For a lot of flats and terraced houses in London, that freed-up space is the main reason people go for a combi.<\/p>\n\n\n\n Yes, it\u2019s a condensing boiler rated ErP A<\/strong>, and published listings put its seasonal efficiency at roughly 93%.<\/p>\n\n\n\n In plain terms, a boiler like this wastes far less heat than an old non-condensing model. If you\u2019re replacing a boiler that\u2019s 15 or more years old, you\u2019ll likely notice the difference in your gas bill.<\/p>\n\n\n\n How much you actually save depends on your insulation, your radiators and how you use your heating. We\u2019d rather tell you that than promise a number we can\u2019t guarantee.<\/p>\n\n\n\n It\u2019s a good match if:<\/p>\n\n\n\n It\u2019s worth thinking twice if:<\/p>\n\n\n\n A flow rate of around 10 litres a minute is fine for one shower and a kitchen tap. Ask for more at once, and you may notice weaker pressure or a drop in temperature. In that case, a higher-output Worcester combi is the safer choice.<\/p>\n\n\n\n Most customers can expect to pay around \u00a31,775 to \u00a32,275<\/strong> for supply and installation.<\/p>\n\n\n\n Where you land in that range depends on:<\/p>\n\n\n\n The best way to avoid surprises is a quote based on your actual home, not a general online figure.<\/p>\n\n\n\n It\u2019s less mysterious than it sounds. A Gas Safe registered engineer will:<\/p>\n\n\n\n Only a Gas Safe registered engineer can legally install a gas boiler, so always ask to see the ID card.<\/p>\n\n\n\nThe quick answer<\/strong><\/h3>\n\n\n\n
Key specs at a glance<\/strong><\/h2>\n\n\n\n
<\/th> Worcester Greenstar 25i<\/th><\/tr><\/thead> Type<\/td> Gas condensing combi<\/td><\/tr> Central heating output<\/td> 24kW<\/td><\/tr> Hot water output<\/td> 25kW<\/td><\/tr> Hot water flow rate<\/td> About 10.2 litres a minute (at 35\u00b0C rise)<\/td><\/tr> Energy rating<\/td> ErP A (around 93% seasonal efficiency)<\/td><\/tr> Typical home<\/td> 1 bathroom, small to medium size<\/td><\/tr> Standard guarantee<\/td> 5 years, with longer cover possible via an accredited installer<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n What kind of boiler is it?<\/strong><\/h2>\n\n\n\n
Is the Greenstar 25i energy efficient?<\/strong><\/h2>\n\n\n\n
Who the 25i suits best<\/strong><\/h2>\n\n\n\n
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When we\u2019d suggest something bigger<\/strong><\/h2>\n\n\n\n
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What we like<\/strong><\/h2>\n\n\n\n
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What we\u2019d flag<\/strong><\/h2>\n\n\n\n
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How much does it cost to install?<\/strong><\/h2>\n\n\n\n
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What actually happens on installation day?<\/strong><\/h2>\n\n\n\n
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A few checks worth doing before you buy<\/strong><\/h2>\n\n\n\n
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Greenstar 25i vs a bigger combi<\/strong><\/h2>\n\n\n\n