Hot Water Cylinder Replacement Cost
How much to replace a central heating hot water cylinder?
The typical cost to replace a central heating hot water cylinder in the UK ranges from £500 to £2,000+, depending on the type, size, and complexity of the installation.
These prices include the cost of installing or repairing a hot water cylinder within a central heating system as well as the ancillary plumbing around it such as hot water valves, pipework, immersion heaters and thermostats.
In this introductory guide, we break down the average cost to replace a hot water cylinder and explain the difference between vented and unvented systems.
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User submitted prices
| Job type | Description | Price | Units | Region |
|---|---|---|---|---|
Hot water cylinder (vented / unvented) | Remove old direct immersion heater and cold water tank and hew install of 120 litre direct cylinder with pressure valves | £1,250 | Total price | South East |
Hot water cylinder (vented / unvented) | replace 150L unventred hot watere cylinder with immersion. | £2,300 | Hourly rate | East of England |
Hot water cylinder (vented / unvented) | One new 36/18 stainless steel cylinder + new immersion heater drained down alter pipe work refill test. one years guarantee. | £640 | Total price | South East |
Hot water cylinder (vented / unvented) | Replace existing hot water tank and immersion heater, change pipes to fit. One day job | £460 | Total price | West Midlands |
Hot water cylinder (vented / unvented) | Pressurised cylinder fitted plus pipe work to existing oil boiler and 11 radiators plus installation of 2 new radiators in 4 bedroom house | £9,585 | Total price | North East |
Hot water cylinder (vented / unvented) | New 900×450 cylinder replaced, my old one had split, New cylinder fitted quickly and very tidy at good cost. New immersion fitted + Cable & new AAV & Inhibitor put into my heating all in the price! | £640 | Total price | South West |
Hot water cylinder (vented / unvented) | strip out leaking 36×18 direct cylinder,fit new cylinder/alter pipework fill and test | £635 | Total price | London |
Hot water cylinder (vented / unvented) | replace 1500×300 hw cylinder with new 1500×300 hw cylinder and new immersion including associated materials | £670 | Total price | London |
Hot water cylinder (vented / unvented) | supply and fit 150ltr indirect unvented cylinder, adjust pipework from top to side entry, new immersion, re wire control panel. | £4,400 | Total price | South West |
Hot water cylinder (vented / unvented) | Hot Water Tank replacement 117ltr | £1,295 | Total price | South East |
Hot water cylinder (vented / unvented) | Replace leaking cylinder like for like slightly altering pipework. 28 mm fittings, gravity fed. | £670 | Total price | East of England |
Hot water cylinder (vented / unvented) | replace cylinder hot water and central heating valves and immersion heater | £935 | Total price | South West |
Hot water cylinder (vented / unvented) | For replacing a faulty 117 ltr Hot water cylinder for a new 140 ltr cylinder, Including a new Immersion heater and piping. All materials supplied by Plumbase and PTS. | £657 | Total price | South East |
Hot water cylinder (vented / unvented) | drain hot water system, remove cylinder & re position cylinder, alter heating circuit by supplying & fitting 3 port valve, new remote pump & valves | £1,559 | Total price | South East |
What is a hot water cylinder?
A hot water cylinder stores hot water for your home’s taps, showers, and sometimes heating. There are two main types:
- Vented cylinders get their water supply from a tank of cold water which is often stored in the loft. The system relies on gravity to determine the pressure of the water supply.
- Unvented cylinders are pressurised systems that are connected directly to the mains, usually delivering higher pressure.
A central heating boiler typically heats the water which is then stored in the cylinder ready to supply taps and showers. Some cylinders also have electric immersion heaters as a backup.
Signs you may need to replace a hot water cylinder
In some cases, a faulty hot water cylinder may be able to be repaired, but there are some clear signs that your hot water cylinder needs to be replaced. These include:
- Water leaking from the cylinder
- Rust or signs of corrosion
- Very slow hot water recovery
- Loud kettling or banging noises
- Over 15 years old (end of typical lifespan)
- Failing immersion heater or thermostat
What factors affect the cost of hot water cylinder replacement?
Several elements can influence how much you pay to replace your hot water cylinder:
1. Type of cylinder
Unvented cylinders are more expensive to supply and install because they require specialist knowledge and safety components (e.g., pressure relief valves, tundish). A G3-qualified installer is required by law.
2. Size of cylinder
Standard capacities range from 120 litres (households of 1 to 2 people) to 300 litres (large family homes). Bigger tanks cost more and take longer to install.
3. Labour costs
Labour typically makes up £300 to £700 of the total cost. Prices vary by region (London tends to be higher), and challenging installations can take more time to complete and therefore cost more.
4. Pipework modifications
If pipework or valves are corroded or incompatible, additional upgrades may be needed, typically adding £100 to £300.
5. Boiler compatibility
Your boiler needs to be compatible with the type of cylinder you are installing. If upgrades to the system are required, this can increase the cost significantly.
How long does hot water cylinder replacement take?
A like-for-like hot water cylinder swap typically takes 4 to 8 hours while more complex upgrades (like converting from vented to unvented) can take a full day or longer.
Do I need a qualified installer?
Yes, especially for unvented systems, as these are governed by Part G3 of UK Building Regulations. Installation must be done by a G3-certified plumber and may need to be registered with your local building control.
Look for plumbers who are:
- Gas Safe registered (if working with boiler integration)
- Members of CIPHE, APHC, or WaterSafe
- Able to provide certification for Building Control (especially for unvented installs)
More tips for homeowners
- Stick with the same type of cylinder unless you need to upgrade performance or water pressure.
- Combine installation with other plumbing work to save on labour.
- Check if your cylinder is still under warranty as some stainless-steel models have 25-year guarantees.
- Ask about energy-efficient options as modern insulated cylinders lose less heat and save money long-term.
Remember to find and compare at least 2 to 3 quotes and recommendations from qualified plumbers to be sure you are getting a fair price and quality service. Always request:
- A written estimate
- Confirmation of G3 certification (for unvented)
- Breakdown of labour, parts, and VAT
- Expected timescale for completion
- Testimonials from previous customers.
