4.9 on Trustindex · 236+ reviews
Air Source Heat Pumps · An efficiency upgrade for your tub

The same warm tub,
using less energy.

Every Garden Hub tub ships with a quality electric heater built in. That's all you need to enjoy it from day one. A heat pump is an optional upgrade that uses roughly a quarter of the electricity for the same heat, and pairs neatly with the heater you already have.

Around a quarter of the energy use
Free UK delivery
Trusted site
Professional install
01 / The thesis

Your tub's electric heater works beautifully on its own. A heat pump just lets it do the same job with far less energy , for years.

The electric heater fitted to every hot tub is honest, simple and reliable: one kilowatt-hour in, one kilowatt-hour of heat out. Tens of thousands of tubs run perfectly happily on theirs alone. It's the standard for a reason.

A heat pump is closer to four-to-one. It uses a small amount of electricity to move heat that already exists in the outside air into your water. Same warm tub, much less energy. The technology is the same as your fridge, run in reverse.

02 / The numbers

A quarter of the energy,
same warm tub.

Your tub uses energy whatever you do. Heat is heat. A pump just lets it use roughly a quarter as much. The bigger the tub and the more you use it, the more meaningful the difference.

~75%

Less electricity drawn from the grid for the same amount of heat in your water

Mid-range inverter pump, mild ambient conditions

Heat delivered per unit of electricity used (COP) at mild UK temperatures

Manufacturer COP figures, A15 / W26
−1 °C

How small the temperature drift is overnight when the pump trickle-heats vs cycles on/off

Inverter pump, well-insulated tub
10–15 yr

Working life of a quality inverter pump; savings keep compounding the whole time

Manufacturer expected service life
Built-in electric heater · standard
1kWh 1kWh heat
Honest, simple, perfectly capable on its own.
  • Built into every Garden Hub tub; nothing extra to install
  • Reliable, well-proven hardware with a long service life
  • Always there as a fast top-up, even after a pump is added
  • Fine for moderate, year-round household use
With an air source heat pump · upgrade
1kWh 4kWh heat
Three of those four kWh come from the outside air, free.
  • Roughly a quarter of the electricity for the same heat
  • A much smaller carbon footprint over the tub's life
  • Inverter pumps stay efficient down to UK winter temperatures
  • Discounted bundle price when added with your hot tub

Figures show electricity drawn vs heat delivered, at mild ambient. Real-world ratio varies with weather and use.

03 / How it works

A fridge,
run in reverse.

A heat pump doesn't generate heat. It moves heat that's already there. That distinction is the entire reason it's three or four times more efficient than a resistive electric element, and why the maths works out the way it does.

Schematic · refrigerant cycle
Air source heat pump refrigerant cycle diagram Outside air at +8 °C enters an evaporator coil, the refrigerant is pressurised by a compressor, hands its heat to hot tub water at 38 °C through a condenser, and the cycle repeats. OUTSIDE AIR +8°C HOT TUB WATER 38°C REFRIGERANT LOOP · R32 EVAPORATOR C COMPRESSOR CONDENSER air in water heat moves left → right
Energy in
1 kW
electricity from the grid
Heat out
4 kW
delivered to the water
  1. 01

    Pull air across the coil

    A quiet fan draws outside air through a refrigerant-filled coil. Even at 0 °C, that air carries a remarkable amount of usable thermal energy.

  2. 02

    Compress the refrigerant

    An inverter compressor pressurises the refrigerant; the same step that happens inside a fridge, just running in the opposite direction. Pressure equals heat.

  3. 03

    Hand the heat to the water

    The hot refrigerant passes through a titanium heat exchanger. Your tub's water flows past it on the other side and warms by 3–5 °C per pass.

  4. 04

    Send the cold air back out

    The now-cooled refrigerant cycles back to the start, and slightly cooler air leaves the back of the unit. The cycle repeats until your set point is reached.

04 / Beyond the energy

Efficiency is
only the start.

The energy maths is the obvious win, but six other things change the day a heat pump goes on the wall. Some of them, you'll notice on the first evening.

/ Carbon

A fraction of the carbon footprint

With grid electricity getting cleaner every year, a heat pump's already-low carbon profile keeps falling. On a 100% renewable tariff, the running emissions are essentially zero.

/ Quiet

Quieter than a kitchen extractor

Modern inverter pumps run between 36 and 48 dB at one metre, barely audible from the patio, and a long way from the on-off thump of older fixed-speed units.

/ Stable

Steadier water temperature

Inverter pumps trickle heat in continuously instead of cycling on and off, which means the water stays within a degree of your set point all day rather than drifting up and down.

/ Cooling

Reverse-cycle cooling in summer

Most of our pumps run in reverse on the hottest days, pulling heat out of the water, so a 38 °C August tub becomes a 28 °C plunge. One unit, two seasons.

/ Lifespan

Less wear on the tub heater

When the heat pump does the heavy lifting, the tub's built-in element only kicks in occasionally as a top-up. That doubles the realistic life of the original heater.

/ Smart

Schedule it from your phone

Wi-Fi enabled units (5 kW and up) let you pre-warm the tub from the train home, dial back overnight, and track energy use in real time through the manufacturer app.

05 / Installation

Half a morning,
same crew, same day.

The pump sits outside, next to the tub. It plugs into a standard 13 A outdoor socket, and a pair of flexible hoses connect it to your tub's existing pipework. So it doesn't need its own water supply or its own electrical circuit. We fit it alongside the tub on delivery day.

Plan view · siting

The pump sits outside the tub's equipment bay, hoses tucked behind. No trenching, no buried pipe.

Top-down site plan: heat pump position relative to hot tub and 13 A socket A heat pump sits to the left of a hot tub on a patio. Two flexible hoses connect it to the tub's equipment bay. A 13 A outdoor socket sits in the corner of the patio. Sixty centimetres of clearance is shown at the front of the unit for airflow. PATIO / DECK hot tub EQUIP. BAY heat pump hot return cold feed 13 A SOCKET air in 60 cm
What we need on site
Power
Standard 13 A outdoor socket, same as a garden lawnmower. No new circuit, no electrician callback.
Footprint
Roughly 80 × 35 cm of floor or paving, placed within 3 m of the tub for the supplied hose run.
Airflow
Clear 30 cm at the back, 60 cm at the front. Walls and fences are fine; tight corners aren't.
Plumbing
Two flexible hoses run from the pump into the tub's existing equipment bay; no permanent pipework.
Drainage
A small condensate drip in winter. We position the unit so it runs onto a flowerbed or gravel, not the patio.
No separate trade required. The Garden Hub install crew commission the pump alongside your hot tub on the same delivery, usually within 90 minutes of the tub being filled.
06 / Compatibility

Will it work
with my tub?

Heat pumps connect to the hot tub's existing pipework. They don't need their own water supply. Almost any modern 230 V tub is a candidate, and every Garden Hub tub is shipped pre-plumbed for one.

Yes
Any of our hot tubs
Pre-plumbed for a heat pump out of the box. Bundle pricing applies.
Yes
Our swim spas
The biggest gains live here. Swim spas hold a lot of water, and a pump moves heat into all of it efficiently.
Yes
Most other 230 V plug-and-play hot tubs
If your tub has an external bypass kit available (most do), the pump retrofits in an afternoon.
Maybe
Hard-wired permanent installs
Possible, but needs a survey; we'll come and look before quoting.
No
Inflatable / Lay-Z-Spa style tubs
The plastic shell can't hold the pressure or temperature differential reliably.
07 / Common questions

The questions we get
before every install.

/01 Does the heat pump replace the tub's built-in heater, or work alongside it?
It works alongside it. The pump does 90%+ of the heating efficiently, and the original element stays as a backup for the coldest few days a year, or for a fast top-up if you want the tub at temperature in under an hour.
/02 Does it have its own water supply?
No. Two flexible hoses run from the pump into your tub's existing equipment bay. The water that's already in your tub circulates through the pump, gets warmed, and goes back in. There's no plumbing into your house.
/03 Does it have its own power supply?
It plugs into a standard 13 A outdoor socket, the same kind of outlet a garden lawnmower uses. The 3 kW unit pulls about 600 W; the 9 kW flagship pulls around 1.5 kW. No new circuit needed.
/04 How loud is a hot tub heat pump?
All four of our pumps run between 36 and 49 dB at one metre, depending on speed. For reference, a fridge hum is around 40 dB. From a few metres away on a patio, you won't hear it over a normal conversation.
/05 Will it still work in winter?
Yes. Our entry pump is rated to −5 °C ambient, the mid-range to −15 °C, and the IceSpa and Mr. Silence flagship to −10 to −20 °C. UK winters very rarely fall below those, and on those few nights, the tub's built-in element steps in.
/06 Can I retrofit a heat pump to a hot tub I already own?
Almost certainly, if it's a 230 V plug-and-play tub from the last decade. The same hose-and-bypass kit works on most of them. Send us a photo of your tub's equipment bay and we'll confirm before quoting.
/07 Does a hot tub heat pump need servicing?
Once a year. Hose down the coil, check the refrigerant pressure, clean the fan. We offer it as part of the standard tub service if you'd rather not.
Bundle one with your tub

A heavy discount on the pump.
A long, quiet payoff after.

Add a heat pump at checkout for the bundle price. Installed alongside your hot tub on the same delivery; same crew, same morning.

Heat pump questions?