Topic
Heating and running costs
Most inflatable tubs plug into a 13 A socket with a heater of about 2.0 to 2.2 kW. Heating from cold takes many hours; keeping the water warm under a good cover costs far less than heating it again.
- Typical heater
- 2.0 to 2.2 kW
- Usual maximum
- 40 °C
Heating water takes a fixed amount of energy: 1 litre warmed by 1 °C needs about 4.186 kJ. For 800 litres from 10 °C to 38 °C that is about 26 kWh before any losses, or roughly 12 hours at 2.2 kW. The heat-up calculator does the sum with your own unit rate in p/kWh.
Real times are longer, because heat escapes through the walls, the cover and the air, more so on cold or windy days and with the bubbles running. Keeping the cover on, adding a floor mat and sheltering the tub from wind all help.
Use a dedicated outdoor socket where possible and follow the maker's instructions on extension leads and RCD protection. Some tubs cannot run the heater and the bubbles at the same time on a 13 A supply.
Common mistakes
- Using the maker's heating rate per hour as if it held in a British winter.
- Leaving the cover off for long spells while the heater runs.
- Copying a running cost figure from someone else's tariff instead of using your own p/kWh.
Guides on this topic
- Thermal cover vs inflatable lid for an inflatable hot tubThermal cover vs the standard inflatable lid compared on heat retention, fit, handling and when an upgrade makes sense for an inflatable hot tub.Comparison
- Should you leave an inflatable hot tub on all the time?Should you leave an inflatable hot tub on all the time? Keeping the heater on against switching off, overnight running, timers and filtration explained.Guide
- Inflatable hot tub heater not working: causes and fixesInflatable hot tub heater not working? Check filter flow, timer and lock settings, the heater button, air temperature limits and when to call the maker.Fix
- Can you run an inflatable hot tub on an extension lead?Can you run an inflatable hot tub on an extension lead? What makers say, why a 13 A heater load matters, and the safer option of an outdoor socket.Guide
- How to insulate an inflatable hot tubHow to insulate an inflatable hot tub: ground mats, cover upgrades, wind shelter and pump care that cut heat loss without blocking vents or voiding warranty.How-to
- How long does an inflatable hot tub take to heat?How long an inflatable hot tub takes to heat: the one line sum from litres, temperature rise and heater kW, typical hours for 2 kW heaters and what slows it.Guide
- Hot tub keeps tripping the RCD: what to checkHot tub keeps tripping the RCD or breaker? Damp plugs, extension leads, other loads on the circuit and pump faults explained, with when to call an electrician.Fix
- Hot tub temperature settings explainedHot tub temperature settings explained: the 40 °C maximum most makers set, typical settings, heating timers and holding a lower temperature between uses.Guide
- Inflatable hot tub running costs in the UKInflatable hot tub running costs worked out in kWh from heater rating, heat-up and holding time, with how season, cover and air temperature change the total.Guide
- Hot tub heat pump vs the built-in heaterHot tub heat pump vs the built-in heater explained: how each heats water, what changes in kWh, and when a heat pump suits an inflatable hot tub.Comparison
- 13 amp vs 32 amp hot tubs explained13 amp vs 32 amp hot tubs: why inflatables run from a plug, why 32 A tubs can heat and run jets together, and what each means for kWh and installation.Comparison