How Heat Pumps Save You Money on Hot Tub Energy Bills
Max PiggottHot tubs are a fantastic way to relax and improve your wellness, but there’s no denying that heating the water can add to your monthly energy bills, especially when the weather cools down.
That’s where heat pump technology comes in, a smarter, greener way to keep your spa warm while lowering costs. If you’re wondering whether a heat pump is worth it for your hot tub, here’s how it works and why it can save you money.
What Is a Heat Pump?
A heat pump is a highly efficient heating system that doesn’t create heat the way an electric heater does. Instead, it pulls heat from the surrounding air and transfers it into the water.
Think of it like a reverse air conditioner, instead of cooling your home by pushing heat outside, a heat pump captures warmth from the air and directs it into your spa water.
Energy Efficiency That Cuts Bills
Traditional spa heaters convert electricity directly into heat, often with an efficiency rating of 1:1 (one unit of energy in = one unit of heat out).
By comparison, heat pumps can achieve efficiency ratings of 3:1 to 5:1, meaning for every unit of electricity they use, they produce three to five units of heat.
That can mean a substantial saving on your hot tub’s heating costs, depending on your spa, settings and the weather.
Perfect for Year-Round Soaking
One of the best things about hot tubs is being able to use them in every season. But in cooler weather, traditional heaters work harder and drive up your bills.
Heat pumps still perform efficiently even in cooler climates, making them ideal for autumn and spring soaking, and they reduce the strain on your electric heater during winter.
Long-Term Investment, Long-Term Savings
Yes, installing a heat pump may cost more upfront than sticking with a standard electric heater. But because it drastically reduces your energy usage, the savings add up quickly.
With regular use, the savings help offset the cost of the heat pump over time. After that, it’s pure savings.
Eco-Friendly Bonus
On top of saving money, heat pumps are better for the environment. Using less electricity means a lower carbon footprint, which makes your spa time not only relaxing but also more sustainable.
COP explained simply
COP stands for coefficient of performance. It is the amount of heat a heat pump delivers for each unit of electricity it uses. A standard electric spa heater has a COP of 1: 1 kWh of electricity gives 1 kWh of heat. A heat pump with a COP of 4 gives 4 kWh of heat from the same 1 kWh of electricity, because it moves the other 3 kWh in from the outside air.
COP is not fixed. A heat pump works hardest when the outside air is cold, so its COP is highest on a mild day and lowest on a freezing night. That is why manufacturers quote a range rather than a single figure.
Worked examples at today's electricity prices
From 1 October to 31 December 2026, the Ofgem price cap sets an average electricity unit rate of 26.32p per kWh for Direct Debit customers. Rates vary by region and tariff, so check your own bill.
Example 1: the first heat-up of a 1,000 litre tub
Raising 1,000 litres from 10°C to 38°C takes about 32.6 kWh of heat, before any heat loss.
| Heating method | COP | Electricity used | Cost at 26.32p/kWh |
|---|---|---|---|
| Electric heater | 1 | 32.6 kWh | about £8.58 |
| Heat pump, cold day | 3 | 10.9 kWh | about £2.86 |
| Heat pump, mild day | 4 | 8.2 kWh | about £2.15 |
| Heat pump, warm day | 5 | 6.5 kWh | about £1.72 |
Example 2: every 10 kWh of heat, season by season
Your tub's daily heat demand depends on its size, cover, location and how often you use it, so we cannot give one figure for everyone. Instead, this table shows what every 10 kWh of heat would cost. The COP figures are assumptions for illustration, chosen to reflect lower performance in cold weather.
| Season | Assumed heat pump COP | Electric heater cost | Heat pump cost |
|---|---|---|---|
| Summer | 5 | £2.63 | about 53p |
| Spring and autumn | 4 | £2.63 | about 66p |
| Winter | 2.5 | £2.63 | about £1.05 |
To estimate your own saving, look at how much electricity your tub uses now. If it has its own meter or you can compare bills with and without the tub, you will have a good starting figure.
Sizing a heat pump
A heat pump needs enough output to keep up with your tub's heat loss on the coldest days you plan to use it. For hot tubs, we recommend the Balboa Clim8zone II Mini. It delivers 4.0 kW of heat with 27°C air and 2.5 kW with 15°C air, and is rated for water volumes of 5 to 15 cubic metres. For swim spas, the larger Clim8zone II heat pump has a heating capacity of 6 kW, double the 3 kW electric heater in our larger hot tubs, to suit the much bigger volume of water.
Noise
A heat pump has a fan and a compressor, so it makes some noise when it runs. The Clim8zone II Mini for hot tubs is rated at less than 45 dBA, and the larger swim spa model at less than 50 dBA. Place it away from bedroom windows and your neighbours' seating areas, and on a solid, level surface to keep vibration down. For noises from the spa itself, such as humming, gurgling or grinding, see our hot tub noise troubleshooting guide.
Winter performance
The Clim8zone II Mini for hot tubs works in air temperatures down to -5°C, and the larger swim spa model down to -20°C. Both keep working in a British winter, but they extract less heat per unit of electricity on a cold night than on a mild one. A good, well-fitting cover matters more than ever in winter, whatever is doing the heating. If you own a swim spa, our swim spa winter care guide covers heat modes, frost protection and covers as well.
Installation, step by step
- Check compatibility. The Clim8zone II Mini works with Balboa BP systems with model numbers ending in "C8Z", and with Spa Touch 2, Spa Touch 3, TP700 and TP740 topsides. Tell us your spa model and control panel before you order.
- Choose the position. The Mini measures about 50 x 50 x 49 cm, and the larger swim spa model about 80 x 41 x 43 cm. It needs free airflow around it, a solid level base and a short pipe run to the spa.
- Plumbing. The heat pump is plumbed into the spa's circulation so water passes through it.
- Electrics. The electrical connection must be made by a qualified electrician.
- Set up the controls. Once connected, you can choose heating, cooling or automatic mode from the spa panel.
- Test. Check for leaks and confirm the water temperature is rising as expected.
What the manufacturer claims
Balboa states that the Clim8zone II range typically delivers 5 to 10 times the efficiency of a traditional spa heater, up to 15 times in optimal conditions, and quotes savings of up to 80% on heating costs for the larger swim spa model. These are the manufacturer's figures. Your results will depend on your tub, your cover and the weather.
Is a heat pump worth it for you?
A heat pump makes most sense when heating is a large part of your running cost. You are likely to see the biggest benefit if:
- you have a large hot tub or a swim spa with a lot of water to keep warm
- you use it all year, including through the winter
- you keep it at temperature every day rather than heating it up occasionally
- your control system is a compatible Balboa BP series
It makes less sense if you have a small plug and play tub that you use mainly in summer, where heating costs are already modest. In that case, a new cover or a more sheltered spot may save more for less outlay. A heat pump is also a fixed piece of equipment with its own plumbing and electrics, so factor in the installation work as well as the unit price.
Heat pump FAQs
Can a heat pump cool my water too?
Yes. Both the Mini and the larger swim spa model can heat or cool, which is useful in a hot summer.
Will a heat pump work in a UK winter?
Yes. The Mini for hot tubs works down to -5°C and the larger swim spa model down to -20°C, but both are less efficient in very cold air.
Do I still need my spa's electric heater?
Your spa's heater is not removed. On compatible Balboa BP systems you can choose to run the heat pump alone, the electric heater alone, or both together when needed.
How long until a heat pump pays for itself?
It depends on how much heat your tub uses. Work out your current heating cost from your bills, then use the tables above to estimate the saving.
Will it fit my hot tub?
For hot tubs, choose the Clim8zone II Mini, which works with Balboa BP systems ending in "C8Z". If you are not sure which control system you have, call us on 01293 824094.
Adding a heat pump to your hot tub setup is one of the smartest upgrades you can make. By capturing natural warmth from the air, heat pumps cut your energy bills, extend your soaking season, and reduce your environmental impact, all while keeping your spa at the perfect temperature.
So if you love your hot tub but want to lower running costs, it’s time to think about making the switch. Call us on 01293 824094 for further advice.
Choosing a hot tub?
Compare our hot tubs and swim spas, or visit our showroom near Gatwick.