Insights
Signs Your Hot Water Cylinder Is on Its Way Out
Nobody thinks about their hot water cylinder until the morning the shower runs cold. Most electric cylinders last somewhere between 10 and 15 years, and they tend to give you warning signs before they fail completely. Catching those signs early means you can plan a replacement rather than scrambling when it dies.
The most obvious sign is hot water that runs out faster than it used to. As a cylinder ages, sediment builds up in the bottom of the tank and the heating element can start to fail, so you get less usable hot water from the same tank. If you've gone from comfortable showers to running cold halfway through, the cylinder is a likely cause, though it can also be a failed element or thermostat that's cheaper to fix.
Rust and discoloured water are a bad sign. If the hot water comes out with a brown or rusty tinge, especially first thing, the inside of the tank may be corroding. Once a steel cylinder starts rusting from the inside there's no real fix, and it's only a matter of time before it leaks. Have a look at the cylinder itself too. Rust streaks on the outside or around the fittings tell the same story.
Water pooling or damp around the base is the clearest warning of all. A small weep can quickly become a full leak, and a cylinder holds a lot of water. If yours is in the roof space or a cupboard above living areas, a leak can do serious damage to ceilings and floors. Any sign of water around the base means it's time to get it looked at quickly.
Strange noises like banging, popping, or rumbling when the cylinder heats up usually mean sediment has built up in the bottom. The element is heating water trapped under the sediment, which boils and pops. It's not always urgent, but it's a sign the tank is getting tired and running less efficiently.
The pressure and temperature relief valve is one to keep an eye on. This is a safety valve on mains-pressure cylinders that releases if the pressure or temperature gets too high. A bit of dripping from its overflow is normal as water heats and expands, but constant heavy discharge means the valve or the cylinder needs attention. Don't ever cap or block this valve, as it's there to stop the cylinder failing dangerously.
If your cylinder is over ten years old and showing any of these signs, it's worth getting it assessed. Sometimes it's a cheap element or thermostat and you get a few more years. Other times the tank itself is done, and knowing that early lets you replace it before it leaves you with cold showers or a flooded cupboard. Replacing hot water systems is restricted work, so it needs a licensed plumber to do it properly and sign it off.