A plug-in hot tub does not have to cost a fortune to run. Most of the bill comes from heat you lose and then pay to put back. These twelve tips cut that loss, starting with the free ones. Where we quote a cost, we use 25p per kWh as an assumption. Check the unit price on your own bill.
The free tips
1. Keep the lid on and strapped
Most heat walks off through the surface as steam. Put the lid back the moment you climb out and clip every strap so the wind cannot lift a corner. More in hot tub covers and heat loss.
2. Hold a steady temperature
Letting the tub drop to air temperature and reheating it from cold costs more than holding it warm, in most cases. A full first heat of 1,000 litres from 15 °C to 38 °C takes about 26.7 kWh, roughly £6.67 at our assumed 25p. If you will use the tub again within a couple of days, keep it warm.
3. Drop it a couple of degrees
You may not notice the difference between 38 °C and 36 °C. The heater will, because the tub loses heat faster the bigger the gap to the air outside.
4. Keep sessions shorter with the lid off
Plan your soak. Every minute the lid lies on the patio, steam carries heat away.
5. Turn the bubbles off when you do not need them
The air blower pushes cold outside air through the water. On the Arebos Barcelona 6 the blower is rated at 600 W, so 30 minutes uses 0.3 kWh, about 7.5p. Not much on its own, but the cold air also cools the water, which the heater then has to win back.
6. Turn it down when you go away
For a weekend away, lower the set temperature rather than switching off. For a long break, drain the tub fully. In frost, never leave water in a tub that is switched off.
The cheap tips
7. Put a mat under the tub
The ground is cold all year. A foam floor mat or insulated tiles slow heat loss through the floor. The Arebos and the Wave Atlantic 6 EnergySave bundle include one.
8. Add a floating thermal blanket
A bubble sheet laid on the water under the lid cuts evaporation further. It costs little and you can cut it to fit.
9. Shelter it from wind
A fence panel, screen or hedge on the windward side helps every night of the year. See where to put a hot tub.
10. Keep the filter clean
A clogged filter makes the pump work harder and slows heating. Rinse it every few days of use. Our filter guide shows how.
The tips that depend on your tub
11. Heat on cheap electricity
If your tariff has cheaper night rates, heat the water then. A tub with app control makes that easy, because you can set it from your phone. Eleven of the fifteen Lay-Z-Spa tubs we list have app control, including the Rome, Carrara and Toronto. See all hot tubs with app control.
12. Choose the right wall, and the right size
If you have not bought yet, this tip beats all the others. The wall decides how fast the heat leaks out:
| Wall | Maker's claim | Examples |
|---|---|---|
| Foam core | Up to 60 % more efficient (Lay-Z-Spa ThermaCore, Wave WaveEco) | Lay-Z-Spa Toronto, Carrara, Stockholm; Wave Tahoe 4, Garda 6 |
| Insulated liner | Up to 40 % more efficient (Lay-Z-Spa EnergySense) | Lay-Z-Spa Rome, New York, Santorini |
| Plain air wall | none | Lay-Z-Spa Miami, Intex PureSpa range |
These are the makers' claims against their own plain walls. We have not tested them.
Size matters too. Less water means a cheaper first heat and less surface to lose heat from. The Wave Tahoe 4 holds 650 litres, so a first heat from 15 °C to 38 °C takes about 17.3 kWh, roughly £4.34 at 25p. The Intex PureSpa Bubble 8 holds 1,340 litres and needs about 35.8 kWh, roughly £8.94. If you mostly use the tub as a couple, a big tub costs you more for space you do not use.
What does not save energy
- A more powerful heater. A 2,200 W heater and a 1,800 W heater use the same energy to warm the same water by the same amount. The bigger one just gets there sooner.
- Switching off every night. You lose the heat anyway and pay to put it all back.
- Heating with the lid off to "check" it. That wastes heat as steam.
Quick answers
What does a hot tub cost per day? It depends on the wall, the weather, the lid and your tariff. Wave quotes about £2 a day to hold 40 °C in its foam tubs. That is the maker's figure. See hot tub running costs.
Which tub is cheapest to run? Read our cheapest hot tub to run guide for the sums.
Is it worth running a hot tub in winter? Many owners do. Pick a foam wall and read using a hot tub in winter.
