Should you leave an inflatable hot tub on all the time?

What happens when you switch off

When the heater is off, the water cools through the cover, walls and floor. How fast depends on the air temperature, wind and insulation. In mild weather with a good cover, it may drop a few degrees overnight; in a cold snap it can fall much further.

Reheating from a lower temperature takes energy and time. With a 2 kW class heater, raising 800 litres by 10 °C needs at least about 9 kWh and over four hours, before heat loss. Our heat-up calculator works this out for your tub.

Leaving it on versus switching off

Overnight and timers

Many smart and newer tubs, including some Lay-Z-Spa models, have timers or app schedules that let you start heating at a set time. That can mean the tub is ready when you get home without running the heater all day. Check your manual for what your control panel can do, as features vary.

Leaving the tub on overnight with the cover fastened is normal for most owners. The heater simply tops up the temperature as needed. If your energy tariff has cheaper night hours, some owners schedule heating then; work it out in kWh using your own rate.

Do not switch off the filter

Even if you turn the heater off or down, keep the filter pump running for the daily cycle your maker recommends. Moving water through the filter and keeping sanitiser in range is what keeps the water clean. Switching everything off for days invites cloudy or green water; see green hot tub water.

• Keep the cover on and fastened.
• Run filtration daily as the manual says.
• Test and dose a few times a week, even when not soaking.

In winter

In freezing weather, switching the heater off can risk ice in the pipes and pump unit. Many makers advise keeping the tub running above a minimum temperature or draining it fully. Some models have frost protection that switches on automatically. Follow your manual, and see using an inflatable hot tub in winter.

Note:Do not leave a tub filled but switched off in freezing weather unless the maker says it is safe. Ice can damage the pump unit and connections.

A sensible routine

For a full picture of energy use, read running costs in the UK.

1. 1

   Decide how often you will use the tub this month.

2. 2

   If several times a week, keep it heated with the cover on.

3. 3

   If weekly, lower the set temperature between soaks and reheat in time.

4. 4

   If rarely, consider switching off the heater in mild weather, or draining for long breaks.

5. 5

   Improve insulation to make any approach cheaper; see how to insulate an inflatable hot tub.

See well insulated tubs →

Bubbles and the heater

On many 13 A inflatable tubs, the heater pauses while the bubbles run, because both together would draw more power than the plug allows. Long bubble sessions also cool the water, as air is blown through it. If you notice the temperature dropping during a soak, that is usually why. Turn the bubbles off between bursts and keep the cover on when you get out, and the heater will catch up.

Frequently asked questions

Can you leave a Lay-Z-Spa on overnight? Yes, with the cover fastened. The heater keeps the water at the set temperature.

Can I turn my Lay-Z-Spa off at night? You can in mild weather, but you will need to reheat. Keep the filter cycle running and avoid switching off in freezing weather.

Is it cheaper to leave a hot tub on? For frequent use it often is, compared with reheating from cold. For occasional use, turning it down or off can save kWh.

Do I need to run the filter if the heater is off? Yes. Keep the daily filter cycle running and sanitiser in range.