How to Choose a New Boiler: A Simple Guide

Choosing a new boiler shouldn't feel like homework, but with three main types, a dozen brands and prices ranging from under £2,000 to well over £4,000, it's easy to see why so many homeowners put it off. If your old boiler is on its last legs, or you've spotted the signs you need a new boiler, here's how to work out what actually suits your home, without wading through jargon.

Step 1: Work out which boiler type you need

There are three main types of boiler, and picking the wrong one is the most expensive mistake you can make.

• Combi boilers heat water on demand, no tank needed. Great for flats and smaller homes with one bathroom.
• System boilers work with a hot water cylinder, better if you've got two or more bathrooms running at once.
• Regular (heat only) boilers suit older properties with existing tanks and traditional heating setups.

Our combi vs system vs regular boilers guide breaks each one down in more detail if you're still unsure. As a rule of thumb, the more bathrooms and the more simultaneous hot water demand, the less a combi makes sense.

Step 2: Get the size right

Boiler size is measured in kW output, and this is where a lot of people go wrong, either overpaying for a boiler that's too powerful or ending up with weak water pressure because it's too small. The right size depends on your number of radiators, bathrooms and how much hot water you use at once. Our boiler sizing guide walks through the maths, but honestly, this is best left to a Gas Safe registered engineer who can survey your home properly. A qualified installer should always be listed on the Gas Safe Register, which is the only legal register for anyone working on gas appliances in the UK.

Step 3: Compare brands sensibly

Worcester Bosch, Vaillant, Ideal, Baxi and Glow-worm all make solid, reliable boilers, and the "best" one often comes down to warranty length, local parts availability and what your installer recommends fitting. Which? boiler reviews is a useful independent source if you want reliability data before you decide. We've also compared two of the most popular choices head to head in Worcester Bosch vs Vaillant, and rounded up the wider market in our best boiler brands compared guide.

Step 4: Understand the real cost

National suppliers often quote £3,000 or more for a straightforward combi swap, which can put people off replacing an ageing, inefficient boiler even when it's costing more to run and repair. Our new boiler cost guide sets out realistic price ranges by boiler type and property size, and if the upfront cost is the sticking point, it's worth reading about boiler finance too. A more efficient boiler can also reduce your energy use, something the Energy Saving Trust has useful guidance on.

Step 5: Plan for installation

Most straightforward swaps take a day, but moving a boiler's location or upgrading pipework adds time. Check our guide on how long a boiler installation takes so you know what to expect on the day, and once it's in, keep it running well with regular servicing, ideally checked against our servicing frequency guide.

If your current boiler is losing pressure or making strange noises, it might not need replacing at all. Have a look at our guides on boiler pressure and banging noises before you commit to a full swap.

Ready to move forward? Browse our range of boilers, see if we cover your area on areas we serve, or get a fixed price in minutes.