Wave Spa heat pump & solar kit

Wave Spa has become a familiar name in British gardens, and it's easy to see why — the tubs look smart, the colour options are a cut above, and models like the Wave Atlantic strike a nice balance between size and price. As inflatable hot tubs go, they're a genuinely pleasant place to spend an evening.

The one thing a Wave Spa can't escape is how it heats the water. Like virtually every inflatable on the UK market, it uses a resistive heater — and that's the reason a tub that's cheap to buy can be dear to run once the colder months arrive.

Below is the plain explanation, and how a retrofit brings the running cost down while keeping the Wave Spa you already own.

Why Wave Spa tubs cost what they do to run

A Wave Spa heats with a resistive element — reliable, simple, and inherently costly to run. To give one verified concrete example: the Wave Atlantic uses an 1800 W "eco" heater, a 40°C maximum, and holds roughly 800 L as a four-person tub or about 1000 L in the six-person size. Other Wave models vary, so check yours, but the principle is identical across the range.

That "eco" label refers to the element's modest wattage, not to cheap running. Resistive heating is close to 100% efficient — a COP of 1 — so every kilowatt-hour you buy becomes one kilowatt-hour of heat and no more. At the Ofgem price cap of about 26p/kWh (Ofgem cap, Jul–Sep 2026), warming 800–1000 L of water and holding it there through a British night means paying full price for every scrap of that heat, including what leaks straight back out through the inflatable walls.

What a Wave Spa costs to run

Wave Spa doesn't quote a single all-in running cost, and we won't invent one — it hinges on your model, target temperature, how often you soak and how well the tub holds heat. As an industry comparator, here's what a rival brand publishes for a comparable inflatable:

• Lay-Z-Spa's own figures: about £0.60–£1.70 a day, or roughly £18–£50 a month.

That's an optimistic manufacturer range — treat it as a floor rather than a typical winter bill, since real cold-weather use often runs higher. Whatever your figure, it's charged at COP 1 today. Cut the electricity needed to reach the same 40°C and the cost comes down with it. For a breakdown grounded in reality, see our UK hot-tub running-costs guide.

How our retrofit kit fits your Wave Spa

Eco Hot Tubs builds a retrofit kit — a UK-made, efficient air-source heat pump, with an optional solar panel and battery — that bolts on to the Wave Spa you already own. You keep the tub, the liner, the covers and the look you chose it for. We just replace the heater doing the expensive work.

• Heat Pump Only — £895. The efficient heat source alone, for owners chasing lower grid costs.
• Full Eco Conversion Kit — £2,195 (founder price £1,845). Adds solar and battery so more of your warmth comes from sunshine and cheap overnight power.

It's a self-fit kit that suits any inflatable Wave Spa model — the Atlantic and its four-to-six-person siblings included. You're not buying a new hot tub; you're upgrading the one part of it that's costing you. Given the modest water volumes involved (that ~800–1000 L on an Atlantic), a heat pump has plenty of room to work efficiently. Both products are currently reserve / enquiry rather than instant checkout, so we can confirm fit for your model first.

See your Wave Spa's energy, live, from anywhere

One of the quiet pleasures of the full kit is finally being able to see what your tub is doing. Open the app from the sofa or the office and watch it second by second: how much solar and wind you're generating, how full the battery is, what the heat pump is drawing, and the exact water temperature in your Wave Spa.

At the end of each day it hands you a scorecard — energy harvested, heat delivered, how efficiently it ran, and the pounds saved against heating on plain mains. Over a week you start to see the pattern of your own free energy, and the satisfaction of watching the mains barely get a look-in.

Behind all that live data is the same four-part system doing the work: solar panel, battery power box, heat pump and automatic switch box. You just get a clear window into it. Nothing about how you use your Wave Spa changes — only the bill and the carbon. Hot water needn't cost the earth. Explore the full setup on our solar hot tub kit page.

The heat-pump efficiency story — honestly

It comes down to make versus move. That 1800 W eco element makes heat from electricity at COP 1 — full price, every time. An air-source heat pump moves heat, lifting warmth out of the outdoor air and into your water. Because moving heat costs far less than generating it, a heat pump can reach a COP of around 3–5 in milder weather — the same 40°C soak for roughly a third to a fifth of the electricity.

We won't dress up the winter. Cold air carries less usable heat, so efficiency drops — near freezing you're realistically at a COP of about 2–2.5, which makes COP 2–3 a fair planning range for a UK winter, with better figures in spring and autumn. Even at its coldest, it out-performs the resistive element it replaces.

With the Full Eco Conversion Kit, the battery lets you store solar by day and cheap Economy 7 / off-peak electricity overnight — roughly a seven-hour window near 12.5p/kWh, about half the cap — then heat from that stored power rather than peak-rate grid electricity.

What will it save on my Wave Spa?

It depends on your model, tariff, temperature and how harsh your winter gets — so any fixed "£X a year" would be a fiction. We'd rather hand you a real estimate. We run this kit on our own tubs in the UK and monitor the measured performance, and we've built that into an interactive savings calculator where you can enter your own details and see a sensible figure for your Wave Spa.

Rather have a conversation, or want us to check your model fits? Drop us an enquiry and we'll answer straight.

Hot water needn't cost the earth.

Wave Spa is a trademark of its owner; we are not affiliated — our kit is simply compatible with it.

Wave Spa retrofit — frequently asked questions

Does it fit the Wave Atlantic, and other Wave models?

Yes — it's built for the inflatable Wave range in general, including the Atlantic's four-person (~800 L) and six-person (~1000 L) sizes. Because heater boxes and volumes differ across models, we confirm fit for your specific Wave Spa when you enquire.

The Atlantic maxes out at 40°C — will the heat pump change that?

The kit is about reaching and holding your usual temperature far more cheaply, not about pushing past your tub's design limits. Stick to the temperatures your Wave Spa is rated for; the win is the running cost to get there, not a hotter tub.

Is it worth it through winter?

Yes, honestly caveated: efficiency falls in the cold, closer to COP 2–2.5 near freezing than the 3–5 of milder weather. It still beats resistive heating all year, and pairing it with solar and battery to use cheap off-peak power helps most in the coldest months.