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What changes the cost of replacing an immersion heater element?
Replacing an immersion heater element is priced on the cylinder type, how easy the element is to reach, whether the cylinder must be drained and whether the thermostat or wiring also needs work. It combines plumbing and electrical work, so use a competent electrician or plumber, and note that this guide prints no price.
Last reviewed:What is an immersion heater element?
An immersion heater is an electric heating element that sits inside a hot water cylinder, a bit like a large kettle element. It heats the stored water when it is switched on, either as the main way of heating water or as a back-up to a boiler. A thermostat on the element switches it off when the water reaches the set temperature.
Elements wear out. Limescale builds up on them in hard water areas, and the metal can fail. When that happens, the usual fix is to replace the element, the thermostat or both, rather than the whole cylinder.
This guide does not print a price. It explains what changes the quote and what to ask before you agree to one. QuoteZila starts in Cheshire, with Crewe, Nantwich and Sandbach first, and anyone in the UK can post the job.
Signs the element may have failed
These signs are reasons to get the immersion heater checked:
- No hot water when the immersion is on, though the boiler or other source still works.
- Water only lukewarm after the usual heating time.
- The fuse, circuit breaker or RCD trips when the immersion is switched on.
- Water far too hot, which can point to the thermostat rather than the element.
- Hissing, crackling or knocking from the cylinder, which can be limescale on the element.
- A damp patch or drip round the element boss on the cylinder.
A tripping RCD or a leak near electrics is a reason to switch the immersion off at its switch and leave it off until it has been checked.
Who should replace an immersion heater element?
This page does not give DIY steps. The job mixes electrical work with draining and refilling a cylinder of hot water. Electrical Safety First says Part P of the Building Regulations requires electrical work in a home to be designed and installed to protect people from fire and electric shock [S1]. It says that, apart from some minor tasks, electrical work must be reported to building control or carried out by a registered electrician who is a member of a government-approved scheme [S1].
Many electricians and plumbers replace elements. The important things are that the person is competent with both sides of the job, tests the circuit afterwards, and gives you a record of what was done. You can find a registered electrician through Electrical Safety First. Electrical Safety First: find a registered electrician; NICEIC; NAPIT. QuoteZila is not affiliated with this organisation.
What changes the price of an immersion heater element?
| Factor | What to ask | Why it moves the price |
|---|---|---|
| Cylinder type | Vented (tank in the loft) or unvented (mains pressure)? | Unvented cylinders have extra safety controls and need the right skills |
| Element position | Top-entry or side-entry? | Side-entry elements usually need more draining |
| Draining | Full or partial drain-down, and how long? | Time and a drain route to outside |
| Element type | Standard, long-life or dual element? | Parts differ in price and fit |
| Thermostat | Is a new thermostat included? | Often worth replacing at the same time |
| Limescale | Will the cylinder be flushed? | Adds time but can help the new element |
| Access | Cupboard space, airing cupboard or loft? | Tight spaces slow the job |
| Wiring and switch | Is the flex, switch or timer in good order? | Faults found may need fixing first |
| Testing and certificate | Will the circuit be tested and recorded? | Should be included, so check |
| VAT | Included or extra? | Changes the total [S4] |
Two quotes can look far apart because one includes a thermostat, a flush and testing, and the other is for the element only. Ask each trader to list every line.
Vented and unvented cylinders
A vented cylinder is fed from a cold water tank, often in the loft, and runs at low pressure. Draining it is usually simpler.
An unvented cylinder is fed straight from the mains and stores water under pressure. It has a pressure relief valve, an expansion vessel or bubble and other controls. Working on it safely needs someone who knows those systems. GOV.UK lists the competent person schemes that cover installing or replacing hot water and heating systems [S2]. Ask whether the engineer works on unvented cylinders before you book.
If you do not know which you have, a photo of the cylinder and any label on it will help the trader tell you. A vented cylinder usually has a cold water tank somewhere above it, often in the loft. An unvented cylinder usually has a cluster of valves and a small pressure vessel close by, and no tank in the loft for it. Those clues are only a guide, so let the trader check.
Limescale and the new element
In hard water areas, limescale forms on the element each time it heats. A thick crust makes the element work harder and can shorten its life. When the cylinder is drained to change the element, it is a chance to deal with scale too.
Ask the trader:
- whether they will flush loose scale out of the bottom of the cylinder while it is empty
- whether a long-life or scale-resistant element is available for your cylinder, and the difference in price
- whether they would suggest a water softener or scale reducer for the house, and what that would cost separately
A trader who opens the cylinder and finds heavy scale or corrosion should tell you before fitting the new part, so you can decide whether to carry on or price a new cylinder.
Before the trader arrives
A few simple steps make the visit quicker and the quote more accurate:
- Find the immersion switch and any timer, and take a photo of each.
- Take a photo of the cylinder, any label on it and the top or side where the element sits.
- Clear the airing cupboard so the trader can reach the cylinder and the pipes.
- Note when the fault started and whether it comes and goes.
- Say whether the boiler, a heat pump or solar panels also heat the cylinder.
If the immersion keeps tripping the electrics, leave it switched off and tell the trader that when you book. Do not take the cover off the element to look inside.
Should you replace the element or the cylinder?
Replacing an element is usually a much smaller job than replacing the cylinder, but there are times to think about the bigger job:
- the cylinder itself is leaking or badly corroded
- the element boss is damaged and will not seal
- the cylinder is too small for the household
- you are changing the heating system, for example to a heat pump
In those cases, ask for prices for both the repair and a replacement. A new cylinder is a larger plumbing job, and GOV.UK says replacing hot water systems is covered by competent person schemes [S2]. Our ground source heat pump cost guide explains how a cylinder fits into a heat pump system.
How do you compare quotes?
Ask each trader for the same details:
- which part has failed, and how they tested it
- the element and thermostat they will fit
- how the cylinder will be drained and refilled
- whether limescale will be flushed out
- what testing they will do afterwards, and what record you get
- whether VAT is included
Citizens Advice says to try to get written quotes from at least 3 different traders, and that some traders charge for quotes, so ask about this first [S3]. It says a quote is a fixed price, while an estimate is just a rough guess [S3]. Our electrician cost guide and plumber cost guide explain how call-out and hourly prices are usually set out.
Jobs you might post
These are examples, not taken from real job posts.
- "Immersion heater gives no hot water but the boiler works. Vented cylinder in the airing cupboard. Please test and replace the element if needed."
- "RCD trips when the immersion switches on. Please find the fault and quote to fix it."
- "Unvented cylinder, immersion back-up stopped working. Please quote, and confirm you work on unvented cylinders."
Posting an immersion heater job
Post the job to electricians or plumbers, and add a photo of the cylinder, the element and the switch. Your job goes to up to five matched local businesses [QZ2]. QuoteZila is free for customers and local businesses [QZ1].
Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.
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Questions about immersion heater element costs
How much does it cost to replace an immersion heater element?
This guide does not print a figure. A top-entry element in a vented copper cylinder that drains easily is a different job from a side-entry element in an unvented cylinder in a tight cupboard. Ask for a written quote that says whether the element, the thermostat, draining and testing are all included.
Is replacing an immersion heater element notifiable electrical work?
GOV.UK says most repairs, replacements and maintenance work do not need to be reported to a building control body, with exceptions such as replacing an electrical fuse box. Electrical Safety First says that, apart from some minor tasks, electrical work must be reported to building control or carried out by a registered electrician. Ask the electrician how the job will be tested and certified.
Is it the element or the thermostat?
Either can fail, and the symptoms overlap. No hot water from the immersion at all can point to the element, while water that is too hot or barely warm can point to the thermostat. An electrician can test both and should tell you which part has failed before replacing anything.
Will the cylinder need draining?
Usually, if the element is being removed. Most elements sit below the water line, so the cylinder has to be drained at least partly. Ask how long the hot water will be off and whether the plumber will flush out limescale while it is empty.
Can any plumber work on an unvented cylinder?
Ask before you book. Unvented cylinders run at mains pressure and have their own safety controls. GOV.UK names competent person schemes for installing or replacing hot water and heating systems. Ask whether the engineer works on unvented cylinders and is registered for that work.
Does VAT change the price?
It can. A business must register for VAT if its taxable turnover for the last 12 months goes over £90,000. Ask whether each quote includes VAT.
Does QuoteZila check electricians and plumbers?
No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.
This page is general information, not professional or legal advice. QuoteZila does not check Gas Safe, WaterSafe, NFRC, NICEIC or other registrations against the register on your behalf: look them up yourself.
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Sources
- QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
- QZ2: QuoteZila product fact. QuoteZila FAQ How does getting quotes work.
- S1: Part P of the Building Regulations, Electrical Safety First. Accessed 2026-10-31. https://www.electricalsafetyfirst.org.uk/find-a-registered-electrician/part-p-of-the-building-regulations/
- S2: Building work, replacements and repairs to your home, GOV.UK. Accessed 2026-10-31. https://www.gov.uk/government/publications/building-work-replacements-and-repairs-to-your-home/building-work-replacements-and-repairs-to-your-home
- S3: Before you get building work done, Citizens Advice. Accessed 2026-10-31. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/
- S4: Register for VAT, GOV.UK. Accessed 2026-10-31. https://www.gov.uk/register-for-vat