Cost guides › Hot water cylinder
United Kingdom
How much does a new hot water cylinder cost?
Replacing an unvented hot water cylinder like-for-like typically costs £2,200 including VAT, with most quotes between £1,700 and £2,850. A basic cylinder fitted by a G3-qualified installer is about £2,100; a premium stainless cylinder with a longer warranty is closer to £2,400. Swapping an old vented copper cylinder costs much less, while converting from a tank-fed system to unvented adds pipework.
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mid-range, typicalCost by region
| Location | Basic | Mid-range | Premium |
|---|---|---|---|
| London | £2,200 | £2,300 | £2,500 |
| Scotland | £2,100 | £2,200 | £2,400 |
| South East | £2,100 | £2,200 | £2,400 |
| East | £2,050 | £2,150 | £2,350 |
| East Midlands | £2,050 | £2,150 | £2,350 |
| North East | £2,050 | £2,150 | £2,350 |
| North West | £2,050 | £2,150 | £2,350 |
| South West | £2,050 | £2,150 | £2,350 |
| Wales | £2,050 | £2,150 | £2,350 |
| West Midlands | £2,050 | £2,150 | £2,350 |
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| Yorkshire and The Humber | £2,050 | £2,150 | £2,350 |
What's included
Mid-range
- Draining down, disconnecting and removing the old cylinder
- A 150-210 litre unvented indirect cylinder sized for a household of 4
- G3 safety kit: expansion vessel, pressure reducing valve, temperature and pressure relief valve and tundish
- Connection to the boiler's heating coil, the mains cold supply and the hot water pipework
- Immersion heater as back-up
- Commissioning, discharge pipe check and building regulations notification
- Taking the old cylinder away
What affects the cost
Vented or unvented
A vented copper cylinder fed from a loft tank is cheap to replace but gives only gravity pressure. An unvented cylinder runs at mains pressure for strong showers, but costs more and must be fitted by a G3-qualified installer with a full safety kit.
Converting from vented to unvented
Going from a tank-fed system to unvented means removing the loft tank, re-piping to the mains and running a discharge pipe to a safe outlet. Your mains pressure and flow must be good enough; the installer should measure them first.
Electric-only homes
Homes without a boiler use a direct cylinder heated by one or two immersion heaters, usually on an off-peak tariff. These cost slightly more than indirect cylinders and need correct electrical circuits.
Size
A 150-210 litre cylinder suits most family homes. Larger cylinders cost more and take longer to reheat; smaller ones run out when several people shower back to back.
Access and space
Airing cupboards are often cramped, and a larger unvented cylinder plus expansion vessel may not fit where the old one was. Moving the cylinder means extra pipework.
Cylinder material and warranty
Stainless steel unvented cylinders often come with long warranties if serviced yearly. Budget models have shorter cover, which matters because unvented cylinders need an annual check of the safety valves.
How to save
- If your vented cylinder is sound and pressure is acceptable, a like-for-like vented replacement is far cheaper than going unvented.
- Ask the installer to test mains pressure and flow before quoting an unvented conversion, so you do not pay for a system your supply cannot feed.
- Replace the cylinder at the same time as a boiler change, when the system is drained anyway.
- Compare quotes that list the same cylinder size, brand and safety kit, and check that building regulations notification is included.
Grants, tax and rules
Unvented cylinders and building regulations
In England, fitting an unvented hot water cylinder is notifiable building work. An installer registered with a competent person scheme self-certifies it and you receive a certificate; otherwise building control must be told before work starts.
Gas Safe for boiler work
If the job involves disconnecting or reconnecting a gas boiler, that part must be done by a Gas Safe registered engineer.
VAT
Our figures include 20% VAT.
Frequently asked questions
How much does a new hot water cylinder cost?
An unvented cylinder replaced like-for-like costs around £2,200 including VAT, with most quotes between £1,700 and £2,850. A vented copper cylinder swap costs much less; converting from vented to unvented costs more.
Is an unvented cylinder worth it?
If you want mains-pressure showers and have good mains pressure and flow, yes. If your supply is weak, a vented cylinder with a pump may work better.
Who can fit an unvented cylinder?
An installer qualified for unvented hot water systems, often called G3-qualified. Ask to see their card and make sure the job is certified or notified to building control.
How long does it take to replace a cylinder?
A like-for-like swap usually takes a day. A vented-to-unvented conversion can take one to two days.
Do unvented cylinders need servicing?
Yes, manufacturers ask for an annual check of the safety valves and expansion vessel, and many warranties depend on it.
How this estimate is calculated
Work hours: 15.2 · Labour: £730 · Materials: £1,095
Sources: ONS Annual Survey of Hours and Earnings, tables 14 and 15; Regione Toscana, Prezzario dei Lavori 2026 (CC BY 4.0); ECB exchange rates; market check: Mid = like-for-like unvented indirect cylinder. Rosebourne Plumbing (2026-07-14): vented 800-1,500, unvented 1,500-3,000, vented-to-unvented 1,800-3,000, unvented from 1,640 + VAT; Checkatrade unvented cylinder: 900-3,500 supply and fit. Incl. VAT..
Last reviewed 26 September 2026 · How we calculate costs · Editorial policy