When Should You Replace a Hot Water Cylinder?

Age is the strongest indicator

Most New Zealand cylinders are replaced somewhere between 15 and 25 years of age, depending on cylinder type, water quality and how well the system has been maintained. If your cylinder is past 20 years, it is reasonable to start planning.

The warning signs

• Water pooling around or under the cylinder
• Rust, corrosion or staining on the casing or fittings
• Hot water running out sooner than it used to
• Discoloured or metallic-tasting hot water
• Rumbling, popping or banging while heating
• Repeated element or thermostat replacements
• Rising power bills without a change in usage

Repair or replace?

A failed element, thermostat or valve on an otherwise sound cylinder is usually worth repairing. Corrosion or a leak from the cylinder body itself means the vessel has failed and cannot be repaired.

On an ageing system, spending on repeated repairs often costs more over a few years than replacing the system once, particularly if the replacement is more efficient.

Planning a replacement

Planned replacements let you consider sizing, whether to move to mains pressure, and whether a heat pump water heater suits the household. Emergency replacements usually mean taking whatever can be installed fastest.