Why am I running out of hot water?

Updated 29 September 2026

Short answer: let the tank reach its set temperature before everyone showers, and on busy days keep the hot water on for longer.

A heat pump heats the tank more slowly than a boiler, so hot water depends on the tank being full and hot before you use it. If several people shower back to back, wait until it has finished heating first.

For guests or a busy morning, extend that day's hot water time or give it a one-off boost. On Cosy Octopus, running it into the 4pm to 7pm peak costs more, so heat it in the 1pm to 4pm period if you can — see the cheap-rate times.

In Snugdays: Boost on Now heats the tank once, to your usual temperature.