Do I need to replace my water cylinder?

An 8-year-old unvented cylinder doesn't automatically need replacing. A well-maintained stainless-steel cylinder can often last considerably longer than this, so it's worth finding out exactly why replacement has been recommended.

Unvented cylinders contain a number of replaceable components, and a fault with one of these doesn't necessarily mean the cylinder itself has failed. Depending on the symptoms, the problem could be with the:

Temperature & Pressure Relief (T&P) valve
Expansion relief valve
Pressure-reducing valve
Expansion vessel
Immersion heater or thermostat
Thermal controls or motorised valves
Pressure gauge or other controls

For example, if you're seeing water dripping from the tundish, this could be caused by a faulty valve or an expansion problem rather than a failed cylinder.

The cylinder itself may need replacing if there is evidence of water leaking from the cylinder body, significant corrosion, a failed internal heat exchanger that cannot be repaired, or another defect affecting the integrity of the cylinder.

I'd ask the person recommending replacement to explain what has actually failed and whether the fault can be repaired by replacing an individual component. If necessary, get a second opinion from a G3-qualified engineer who regularly works on unvented cylinders.

It's also worth checking whether your cylinder is still covered by the manufacturer's warranty. Many stainless-steel cylinders have relatively long warranties on the cylinder itself, although the terms vary between manufacturers and may depend on servicing and installation requirements.

In short, don't assume an 8-year-old cylinder needs replacing simply because it has developed a fault. A proper diagnosis should establish whether the cylinder has actually failed or whether a serviceable component can be replaced.