Lay-Z-Spa heat pump & solar kit

A Lay-Z-Spa is a brilliant thing to own — quick to set up, cosy, and a genuine treat on a cold evening. The one catch is the running cost, and it comes down to a single component: the heater. This page explains why these tubs cost what they do to run, what Lay-Z-Spa themselves say the bills are, and how our retrofit heat pump, solar and battery kit bolts onto the tub you already own to bring those costs down — honestly, with the winter caveats included.

Why Lay-Z-Spas are lovely — but pricey to run

Almost every Lay-Z-Spa heats its water with a resistive electric element, typically around 1.5–2 kW. Resistive heating is simple and reliable, but it's capped by physics at roughly 100% efficient — one unit of electricity gives you exactly one unit of heat, and no more. In efficiency terms that's a COP of 1. There's no way to make a resistive element sip less power for the same warmth; the only way past that ceiling is a different kind of heater.

With UK electricity capped at about 26p per kWh (Ofgem price cap, 1 Jul–30 Sep 2026, direct debit incl. VAT), every unit of heat you lose off the top of the tub is a unit you pay full price to replace. That's fine in summer; it stings in January.

What a Lay-Z-Spa actually costs to run

Lay-Z-Spa publishes its own running-cost estimate:

• £0.60–£1.70 per day
• £4–£12 per week
• £18–£50 per month

(Source: Lay-Z-Spa's own figures.) It's a fair guide, but it's an optimistic manufacturer range — real costs drift toward the top, and beyond, with winter weather, a tired or thin cover, and frequent use. The Lay-Z-Spa range spans roughly 2–4-person up to 7-person tubs (around 600–1200 litres), and a bigger body of water simply costs more to keep warm. Your model and your habits matter more than any single figure.

How our retrofit kit fits your existing Lay-Z-Spa

You don't replace your tub. Our kit is designed to bolt onto the Lay-Z-Spa you already own — any model — and take over the hard work of heating it. There are two options:

• Heat Pump Only — £895. An efficient air-source heat pump that does the heating a resistive element can't afford to. App-controlled, and it heats around twice as fast.
• Full Eco Conversion Kit — £2,195 (founder price £1,845). The heat pump plus a solar panel and battery, so you can heat on your own generated and stored energy — and bank cheap off-peak power for later.

It's built and tested here in the UK, designed to be self-fit onto an existing tub, and app-controlled. Both products are currently available to reserve or enquire about rather than buy outright — we'll help you check it suits your model and setup first.

A complete energy system that bolts onto your Lay-Z-Spa

Your Lay-Z-Spa is a brilliant tub — it just wasn't built to be cheap to heat. Our Full Eco Conversion Kit fixes that without changing anything you love about it. It's a self-contained energy system that sits beside the tub: a 610W bifacial solar panel on an adjustable ground frame, a smart power box with its own battery, an inverter-driven heat pump, and a smart switch box tying it all together.

Sunlight in, power stored, heat out. The panel harvests all year round — no roof, no planning permission, just a frame on the ground you angle to the sun. The power box banks that energy; the switch box decides, moment to moment, whether to draw from your free solar, the battery, or the mains.

It's designed for self-fit, and it leaves your Lay-Z-Spa's own controls exactly as they were. You still use your tub the same way — the difference shows up only on the bill and the carbon. See the full package on our solar hot tub kit page.

The heat-pump efficiency story — honestly

Where a resistive element is stuck at COP 1, an air-source heat pump moves heat from the outside air into your water instead of generating it from scratch. That lets it run at a COP of about 3–5 in milder conditions — using roughly a third to a fifth of the electricity for the same heat.

We won't leave out the important part: heat pumps get less efficient in the cold, because there's less warmth in the air to harvest. A unit near COP 4 on a mild day can fall to around COP 2–2.5 close to freezing, so realistically expect ~COP 2–3 in winter. That's still a big improvement on a resistive element every month of the year — but it's why we won't quote you a fixed annual saving or a neat payback figure. Anyone who does is guessing at your winter, your tariff and your usage.

You can stretch the gains further by pairing the heat pump with an off-peak tariff: an Economy 7-style plan gives roughly a 7-hour overnight window at around 12.5p/kWh (about half the cap rate), and with the battery in the Full Kit you can store that cheap power to use through the day. Add a good cover, a sensible hold temperature and a wind break, and the savings stack.

What will it save on my Lay-Z-Spa?

It depends on your model, how often you use it, the season and your tariff — so rather than invent a number, we'd rather show you a real one. We run actual hot-tub kit in the UK and monitor its measured performance, and we deliberately keep our claims careful and conservative. Try our savings calculator for a personalised estimate on your own setup, then get in touch or reserve a kit if the numbers work for you. Hot water needn't cost the earth.

Lay-Z-Spa is a trademark of Bestway; we are not affiliated — our kit is simply compatible with it.

FAQ

Will the kit fit my Lay-Z-Spa model?

It's designed to retrofit onto any Lay-Z-Spa, from the smaller 2–4-person tubs up to the larger 7-person models. It's self-fit and works alongside your existing tub rather than replacing it. If you're unsure about your specific model, send us a message and we'll confirm before you commit.

How much will a heat pump cut my Lay-Z-Spa running costs?

A heat pump typically uses a third to a fifth of the electricity of the built-in resistive heater for the same heat, dropping to roughly a third to a half in cold winter weather. The exact saving depends on your usage and tariff — our savings calculator gives a personalised estimate.

Do I need to buy a new hot tub?

No. That's the whole point — our kit bolts onto the Lay-Z-Spa you already own, so you keep your tub and just change how it's heated and powered. It's app-controlled and heats around twice as fast as the standard heater.