How Much Does a New Boiler Cost, Installed, in Portsmouth?

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• October 19, 2026
• Boiler Installation
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A new combi boiler supplied and fitted typically costs £2,500 to £4,000 for a straightforward like-for-like replacement, based on current UK trade pricing. Converting from a system or conventional boiler to a combi usually pushes that to around £4,000 or more, because it involves extra pipework and removing the old cylinder, not just swapping one unit for another.

That range is the honest starting point. The real number for your home depends on which boiler type you’re replacing it with, whether it’s staying in the same spot, and what condition your existing pipework and flue are in.

New Boiler Cost by Type — Supplied and Fitted

These figures are drawn from current UK trade pricing guides (Checkatrade) and should be read as a planning range, not a quote — the only way to get an accurate figure is a survey of your specific property.

What Size Boiler Do You Need?

Boiler output is measured in kW, and the right size depends on your property, not a fixed number everyone should ask for. As a general guide:

• 1 bed, 1 bathroom, up to 5 radiators: 9–18kW
• 2 bed, 2 bathroom, 5–10 radiators: 24–27kW
• 3 bed, 3 bathroom, 10–20 radiators: 28–34kW
• 4+ bed, 4+ bathroom, 20+ radiators: 35–43kW

An undersized boiler struggles to heat the property and runs inefficiently; an oversized one costs more upfront without the benefit. This is one of the reasons a proper survey matters more than a quote based on a phone description alone.

Is It Cheaper to Replace Like-for-Like?

Yes, usually. Replacing a combi with a combi in the same location is the cheapest route because it reuses the existing gas supply, flue route, and pipework. Switching boiler type — combi to system, or system to combi — adds cost because it typically means new pipework, removing or adding a hot water cylinder, and sometimes a different flue route entirely.

If your current boiler type suits your home’s hot water demand, like-for-like is usually the lower-cost and faster option. If it doesn’t — for example, a combi struggling to supply hot water to two bathrooms at once — the extra cost of converting can be worth it long-term, but it’s a different financial decision than a simple swap.

What Pushes the Cost Up?

Beyond the boiler type itself, these are the main factors that move the price above the baseline range:

• Moving the boiler to a new location. This typically adds £500–£1,400 on top of the unit cost, according to UK trade pricing, depending on how far it’s moving and how much pipework and flue rerouting is involved. A straightforward move within the same room costs less than relocating to a loft or garage.
• A magnetic filter. Often £110–£310 supplied and fitted, protecting the new boiler from debris already in your heating system.
• A smart thermostat or upgraded controls. Around £150 for the unit, before installation.
• A powerflush. Roughly £1,000 including VAT, recommended when the existing system has a build-up of sludge that could shorten the new boiler’s life.
• Access and disposal. Difficult access to the current boiler, or removing and disposing of an old cylinder, adds labour time.

A quote that doesn’t itemise these separately is harder to compare against another quote — ask whether removal of the old boiler, a magnetic filter, and any making-good work are included before accepting a price.

How Long Does Installation Take?

A like-for-like boiler replacement typically takes 4–6 hours, often completed in a single day. Converting from a conventional or system boiler to a combi usually takes 1.5–3 days, since it involves more extensive pipework changes and removing redundant tanks or cylinders. Moving a boiler to a new location adds time on top of either of these, depending on the distance and complexity involved.

Getting an Accurate Quote for Your Home

The ranges above get you close, but the actual figure for your home depends on your current boiler type, where it sits, and what your pipework and flue look like now. DV Plumbing & Gas’s boiler installation service covers combi, system and conventional boiler installation across Portsmouth and the surrounding area, with a property survey before any firm price is given — not a number guessed over the phone. The team, led by Gas Safe and MCS registered engineer Duncan Vella alongside Rhys Browne, also covers ongoing boiler servicing and repairs once your new boiler is installed.

Ready for an Accurate Price on Your New Boiler?

The ranges in this guide will get you close, but the real number depends on your current boiler, your pipework, and what’s actually behind your airing cupboard — not a UK-wide average. Duncan Vella and the team at DV Plumbing & Gas Services survey your property first, so the price you’re quoted is the price you pay, not a starting figure that grows once work begins.

Get a free boiler installation quote and we’ll tell you honestly whether like-for-like replacement or a conversion is the right call for your home.

FAQ

Does the boiler installation price include VAT? Check this with whoever quotes you — some trade quotes are VAT-inclusive and some are not, and it isn’t always stated clearly. Ask directly before comparing two quotes against each other.

Is a magnetic filter included in a new boiler installation? Not always as standard. It’s a relatively small additional cost (roughly £110–£310 fitted) that protects the new boiler from existing system debris, so it’s worth asking whether it’s included or needs adding separately.

How much more does it cost to move my boiler to a new location? Typically £500–£1,400 on top of the unit and installation cost, depending on how far it’s moving and how much new pipework and flue work is involved. A same-room move costs less than relocating to a different floor or outbuilding.

Can I get a fixed price without a survey? A realistic one is unlikely. Boiler cost depends on your current setup, access, and whether you’re staying with the same boiler type — a firm, accurate price normally needs someone to see the property first, not just hear a description over the phone.