Plumbing advice

Choosing a water heater: a practical guide

Instant versus storage heaters, what size actually fits your household, and the installation details that determine safety and lifespan.

Instant or storage?

Instant (tankless) heaters warm water as it flows — compact and efficient for a single shower, but demanding on your electrical supply. Storage heaters warm a tank of water and hold it — better for households where several people bathe in succession, and gentler on the wiring, but they occupy wall space and reheat slowly.

Sizing a storage heater

Ask your installer to size the heater for your peak demand, available power and the manufacturer’s performance data. Tank volume alone does not tell you how much usable hot water a system can supply.

The installation details that matter

A qualified installer must check the filled weight, support, electrical supply, protective devices and the manufacturer’s pressure-relief requirements. Electrical connections and safety devices require professional assessment. Do not open a heater or alter its wiring yourself.

Signs an existing heater needs attention

Tripping breakers, rust-coloured water, weeping from the relief valve, or a unit that takes noticeably longer to heat are all early warnings. A failed element or thermostat is usually repairable; a corroded tank is not.

Further reading

US Department of Energy: residential water heaters. Use the manufacturer’s model-specific installation instructions and a qualified local installer.