Air Source Heat Pumps for Hot Tubs — Everything You Need to Know

If you own a hot tub and haven't looked into an air source heat pump yet, you're almost certainly spending more than you need to on electricity. This guide explains how they work, what they cost, and what to expect from one in the Lincolnshire climate.

How does a hot tub heat pump work?

A standard hot tub heater element converts 1 unit of electricity into 1 unit of heat — which is expensive. An air source heat pump works differently: it extracts latent warmth from the surrounding air (even in cold weather) and transfers it to your water using a refrigerant cycle, similar to how a fridge works in reverse.

A quality heat pump typically achieves a Coefficient of Performance (COP) of 4–6 in mild conditions. That means for every unit of electricity you put in, you get 4–6 units of heat out.

How much can you save?

Running costs depend on your tub size, usage pattern, insulation quality and local energy tariff. As a rough guide:

• A standard hot tub heater element running year-round in the UK costs £60–£120 per month in electricity
• The same tub with a heat pump typically costs £15–£40 per month — a saving of 60–75%

At current energy prices, most quality heat pumps pay for themselves in electricity savings within 1–2 years for regular users.

Do heat pumps work in winter?

Yes — modern inverter heat pumps are designed to operate down to -15°C ambient temperature, though efficiency decreases as temperatures drop. In the Lincolnshire climate, where temperatures rarely fall below -5°C for extended periods, a heat pump will perform well year-round.

The Poolex IceSpa range is specifically designed for cold-climate performance if you're concerned about winter efficiency.

What size heat pump do I need?

The right size depends on:

• The volume of your hot tub (in litres)
• How quickly you want it to heat up
• Whether you keep it at temperature constantly or heat on demand
• The insulation quality of your tub

As a rough guide: for a 1,000–1,500 litre hot tub, a 5–7kW unit is typically sufficient if you keep it at temperature. For larger tubs or on-demand heating, 9kW+ is preferable.

We carry out a free survey and recommend the right model — we'd rather size it correctly than sell you something too big or too small.

Installation — what's involved?

A standard installation takes around a day and involves:

• Positioning the heat pump unit (it needs airflow around it)
• Connecting to the hot tub's plumbing via a bypass kit
• Electrical connection (we work with approved electricians)
• Insulating exposed pipework
• Commissioning and testing

All our supplied-and-fitted prices include pipework, bypass kit, insulation and electrical work as standard.

What models do we supply?

We supply four models to suit different budgets and requirements — the Poolex O'Spa, Poolex IceSpa, Aquark Mr Silence, and Inverboost PBS. See our heat pumps page for full specifications and pricing.

Ready to cut your running costs? Request a survey or call us on 01472 400673.