Immersion Heater Replacement Cost

Where the money goes

An immersion heater is two cheap parts screwed into a cylinder. What you pay for is getting them out and in without damaging the cylinder. That is why the price of the part and the price of the job are so far apart, and why two quotes for the same failed element can differ by a hundred pounds or more.

These are typical market ranges from published UK cost guides and trade suppliers, not our prices. They vary with the part chosen, the access and how much water has to come out.

• Element: about £15 to £60, depending on length and sheath. A plain copper element sits at the bottom of that range; a scale-resistant Incoloy or titanium sheath costs more and usually lasts longer on hard water.
• Thermostat: about £10 to £25 for a standard rod thermostat with a manual-reset cut-out.
• Fibre washer, and heat-resistant flex if the old one is brittle or scorched: a few pounds.
• Labour: the bulk of the bill. A straightforward top-entry swap is one to two hours on site. A side-entry element, a seized boss or an awkward airing cupboard can double that.

What decides whether yours is a cheap or an expensive job

Four things move the price more than anything else. If you know them before you ring round, you can tell whether a quote is fair.

• Top-entry or side-entry. A top-entry element goes in through the dome of the cylinder, so on a vented cylinder only a few litres need to come out to get below the boss. A side-entry element sits near the base, so most of the cylinder has to be drained first, which can take an hour on its own.
• Seized or free. On hard water the old element and its washer can scale solid into the boss. Freeing it takes time and care, because too much force on the box spanner can distort or split an old copper cylinder. A split cylinder turns an element job into a cylinder job.
• Vented or unvented. An unvented cylinder needs the manufacturer’s specified immersion, which usually costs more than a generic one, and makers expect any work on the cylinder to be done by someone competent in unvented systems, the same skills Approved Document G advises for installing them, which is notifiable work. Expect a higher figure.
• Single or twin element. Economy 7 cylinders often have two immersions or a dual element head. If both have failed, or the timer controlling them has too, the job grows.

If the price you are quoted includes a new cylinder, ask why. A leaking boss seal or a burnt-out element does not by itself mean the cylinder needs replacing.

Element, thermostat or the whole immersion?

Before paying for any replacement, find out which part has actually failed. A thermostat costs a fraction of an element to replace, needs no drain-down, and is the most common cause of an immersion that keeps tripping its reset. Our guide on how to test an immersion heater shows the readings that separate the two.

That said, when the element is being changed most engineers fit a new thermostat at the same time. The thermostat has sat in the same water for the same number of years, the part is cheap, and it saves a second visit when the old one fails a few months later. It is a reasonable add-on, not an upsell.

If the fault is only a tripped cut-out, a replacement may not be needed at all. See how to reset an immersion heater first.

When replacing the immersion is the wrong fix

Sometimes the honest answer is that a new element is money spent on the wrong thing. These are the situations where it pays to stop and think about the cylinder instead.

• The cylinder is weeping at seams or the base, not just at the boss. A new element will not fix a failing cylinder. Compare the figures in hot water tank replacement cost.
• The element fails again within a year or two. That usually points to very heavy scale, a cylinder that is running too hot, or an element sheath that does not suit the water. A better element, and a thermostat set around 60°C, is the fix.
• The immersion is your only source of hot water and the bills are high. Check how much an immersion heater costs to run before assuming the element is the problem.
• The wiring is the fault. A scorched fused switch or a brittle flex is electrical work, and a new element on a failing supply will not last.

Can you replace an immersion heater yourself?

Some people do. It involves isolating and proving the circuit dead, draining the cylinder below the boss, removing the old element with an immersion spanner, fitting the new one on a fresh washer, refilling and bleeding the air out, and checking for leaks before powering up. Switching on an element that is not fully covered by water will burn it out very quickly.

A like-for-like element swap on an existing circuit is not notifiable electrical work under Part P. Adding a new circuit is. On an unvented cylinder, leave it to someone competent in unvented systems, as the cylinder maker will require.

The expensive DIY mistakes are cracking a copper cylinder while freeing a seized element, and a boss that weeps slowly into the airing cupboard floor. If either happens, isolate the water using our guide on how to turn off a hot water cylinder.

What our visit costs, and what happens on it

Getting an engineer to you is the £60 call-out at any hour. The engineer tests the supply, thermostat and element before recommending anything, so you pay for the part that failed, not a guess. The repair price is agreed with you on site before any work starts, and our guide to emergency plumber costs explains how that works.

If the element is replaced, the cylinder is drained only as far as needed, the boss thread is cleaned, and the new element is run up to temperature while the engineer watches the seal. Book through our immersion heater repair and replacement service, or if the cylinder itself is the problem, start from our hot water problems hub.