What is the lifespan of an electric water heater?
What is the lifespan of an electric water heater? The lifespan really depends on what type of electric water heater you have (whether it’s an instantaneous or storage type) and your local water chemistry.
Electric instant water heaters
The internal heating elements are vulnerable to limescale. If you live in a hard-water area and skip water treatment, the elements will overheat and fail in as little as 5 years. However, our range of electric instantaneous water heaters uses “bare wire” technology heating elements. Because they resist scaling and don’t overheat, bare wire elements actually offer a longer product life and better sustained performance in hard water areas compared to their sheathed counterparts
Superior Limescale Resistance (The Big One)
In traditional sheathed elements, limescale sticks to the hot metal sheath, building up like in a kettle and eventually causing the element to overheat and fail. With bare wire, the heating coil is exposed directly to the water
Longer Lifespan in Hard Water
Because there is no solid metal surface for the scale to bond to, and the element has a very low mass, limescale simply doesn’t accumulate in the same way. This makes them exceptionally well-suited for hard water areas like London and the South East, but they are not infallible; we always recommend a water treatment device in hard water areas.
If you are buying an instantaneous electric multipoint heater for a hard water area, bare wire is absolutely the way to go. Just don’t let the idea of “bare live wire in water” put you off—these systems are cleverly engineered so that the water itself acts as the electrical resistor between the live and neutral coils, keeping everything perfectly safe.
Our range of these electric water heaters is detailed here – electric instantaneous water heaters
Electric storage water heaters
Electric storage water heaters come in various options; these are
Modern Direct Stainless Steel Unvented Cylinders
Stainless-steel cylinders of good quality will easily last 25 to 30 years. These must be installed by a qualified engineer in accordance with Part G (Unvented) regulations to receive the 25-year manufacturer warranties.
Stainless steel is the best direct water storage heater and can withstand higher water pressure than copper cylinders – that’s why Flexiheat UK’s range, from 80 litres to 500 litres, is manufactured in duplex stainless steel (the best quality stainless steel for domestic hot water heating) and comes with a 25-year warranty for domestic use. Our range is detailed here – unvented direct cylinders in stainless steel
Copper Cylinders
Copper cylinders usually last 15 to 20 years before pinhole leaks occur.
Glass-Lined Mild Steel Cylinders
These have a sacrificial magnesium anode to prevent corrosion. Generally, they last 10-15 years, but only if the anode is checked and replaced every few years.
The Immersion Heater (The electrical heating element)
While the tank itself might last for decades, the actual electric element inside doesn’t last anywhere near as long. You should expect to replace the immersion element every 5 to 10 years. If you live in a hard water area (London or the South East, for example), you will get limescale build-up on the element, which will cause it to overheat and burn out much quicker.
Flexiheat Engineer’s Advice
The single biggest killer of electric water heaters in the UK is limescale. To actually reach the upper end of that lifespan, your installer must fit an inline scale reducer (like an electrolytic inhibitor) and a magnetic filter. If they just plumb it straight off the mains in a hard water area, they will fur up and burn out prematurely. Always check your local water hardness first!
