Combi Boiler Shower Installation Costs in the UK (2025 Guide)

If your idea of a proper shower is a generous drench, not a polite mist, a combi-fed setup should be on your shortlist. When specified well, a modern combi delivers that hotel feel – hot water at mains pressure, steady temperature, and no faffing with tanks.

If you’re weighing up installation routes as well as shower types, it’s worth reading our electric shower installation costs guide for the alternative.

Combi shower installation cost (UK 2025): the realistic range

Prices depend on scope.

• Simple swap – if your combi is in good health, service valves are in place, and you’re replacing an old mixer with a new thermostatic valve in the same position, expect around £300–£500 all-in. That covers isolating supplies, fitting the valve, reconnecting, pressure-testing and making the wall look like nothing changed.
  
• Upgrades or moves – costs rise when you re-route pipework inside the wall, switch from an exposed bar mixer to a concealed valve with a drencher head, carve out a new valve niche, or add a second outlet like a handset. Once you’ve chased pipework, tanked the recess and re-tiled or panelled, totals often reach £700–£1,200. Moving the shower entirely or working in heritage masonry can push this further.

Work on the boiler itself sits outside these figures. If your combi is underpowered or overdue a service, expect that to come up before anyone opens a wall.

If you’re still weighing technology rather than fittings, see our Electric Shower vs Combi Boiler Shower guide.

What really drives the price (and how to steer it)

Pressure and flow decide comfort long before the tile choice. A combi’s hot-water output depends on its kilowatt rating and your mains supply. A modest 24–25 kW boiler might give you ~9–10 l/min at a typical temperature rise; a 30–35 kW can deliver 12–14 l/min – but only if your mains can match it. If an ancient stopcock or old service pipe throttles flow, no shower head will fix that. A quick flow and pressure check upfront avoids expensive optimism later.

Layout comes next. Moving a shower across the room can transform the space, but it usually means opening walls, re-routing hot, cold and waste, setting correct outlet heights, and planning a tidy valve recess. All doable – better planned than discovered.

Surfaces matter too. Proper waterproofing behind the tile is the difference between a long-lived shower and a slow, costly leak that eats your studwork for breakfast.

Valve choice is the quiet hero of daily comfort. Thermostatic mixers keep your set temperature steady even when someone starts the washing-up downstairs. Manual mixers are cheaper but drift with supply changes. In family homes — or any home really with more than one person — thermostatic pays for itself in comfort.

Running costs vs electric: how the bills behave

A combi heats water centrally and mixes it at the valve. In homes with longer showers or back-to-back users, a combi often feels more natural and can be easier on bills than running an electric element for twenty minutes. There’s no universal winner – your usage patterns decide.

Work out the estimate number for a bathroom renovation with our UK renovation cost calculator.

When a combi-fed shower is the smarter choice (and when it isn’t)

We recommend combi-fed when comfort is the priority: a broad drencher head, steady temperature, and back-to-back showers without the experience falling off a cliff. It’s also the logical pick if your home already runs on a combi and you don’t want to add a dedicated electrical circuit in the bathroom. 

Where we pause: small secondary bathrooms, rentals that need resilience during boiler breakdowns, or annexes far from the main plant. In those cases, an electric shower’s independence is a feature.

If your project includes layout changes and new finishes, see our bathroom renovation approach.

Compliance, waterproofing and ventilation (the unglamorous wins)

Showers are unforgiving. Tank behind tile or panel, set falls so the tray drains cleanly, and size extraction to clear steam quickly (your future paintwork will thank you).  If you’re going concealed with valve and pipework, agree on future access now – no one wants to demolish a feature wall to swap a cartridge. And if the boiler cupboard looks like a time capsule, get it serviced before you chase walls; a temperamental appliance is not a design feature.

Beams’ take: spec the experience, then draw the detail

We start with the shower you actually want to stand under – flow feel, head height, drencher vs handset, who showers when. That decides the spec. Then we test real-world pressure and the combi’s output, design the pipe runs and valve recess so the installer isn’t improvising, and lock it into a fixed proposal. It sounds simple because it is – and it’s why the bathroom still feels brilliant five winters from now.

FAQs: Combi boiler showers (installation, cost, comfort)

How long does a combi-fed shower install take?

A like-for-like mixer swap is usually done in a day, including testing and sealing. A new concealed valve with re-routed pipework often takes two visits, especially when tanking and tiling are involved. Sequence matters: first-fix pipework before finishes, then valve and faceplate, then silicone – your grout lines will thank you.

Do I need a bigger boiler to get a “hotel” shower?

Not always. Many 30–35 kW combis can deliver a strong single shower if the mains is healthy. The quickest check is a measured flow and pressure test at the kitchen tap and at the shower point. If the numbers don’t add up, discuss either a higher-output boiler or adjusting the shower spec.

Can I run two showers at once from a combi?

Usually not well. Most combis are designed for one good hot-water draw at a time. If you want simultaneous showers, consider a system or stored hot-water setup.

Thermostatic or manual mixer—does it really matter?

Yes. Thermostatic valves hold your set temperature even when taps run elsewhere. Manual mixers are cheaper but shift with supply changes. In busy homes, thermostatic is the calmer, safer choice.

What about hard water and limescale?

Hard water targets valves and shower heads. Budget for in-line filtration, consider whole-house softening if needed, and clean heads regularly. Your boiler’s plate heat exchanger will also last longer.

Is a power shower the same as a combi shower?

No. ‘Power shower’ usually means a pumped mixer drawing from tanks – not compatible with a combi (and you can’t legally pump the mains). With a combi, fit a high-pressure mixer and let the boiler and mains do the work.