A COP is a ratio at a temperature, and the temperature is the point
A pool heat pump moves heat out of the air and into the water, and it is the only heating on this shelf whose running cost is a fraction of its output. Two numbers are always published and neither stands alone. The heating output in kilowatts — 3,5, 5, 7, 10 kW here — is what the machine delivers; the COP is how many kilowatts of heat it produces per kilowatt of electricity drawn. The listings advertise COP figures from 5 to 16, and that spread is not a quality ranking: a COP is quoted at a stated air and water temperature, and a COP of 16 is measured at around 26 °C air and 26 °C water — the conditions in which a pool barely needs heating. The same machine at 15 °C air will be nearer 4. A listing that states the conditions is more useful than one with a higher bare number. The third figure is the pool volume the maker rates the unit for — "bis 30.000 l", "34–45 m³" — which already folds in an assumption about cover use that is never stated. Inverter control matters for two reasons: it modulates instead of cycling, which is where the efficiency claim comes from, and it is much quieter. Noise in dB(A) and the distance it was measured at decide whether the unit can sit near a neighbour. And the bypass, which most units need and few include. We compare output, COP with its conditions, rated volume, inverter, noise, connections and what the set contains.
3.5 kW, COP 5.5, up to 12 m³, plug-in
The cheapest heat pump on this shelf and a plug-in one: a Schuko lead, 3.5 kW for pools to 12 m³, and a COP of 5.5 published without the temperatures it was measured at.
Best for: A small above-ground pool where a socket is nearby and the budget is the constraint
7.5 kW inverter, COP to 16, 40–52 dB(A), 10–20 m³
An inverter with a published noise range in decibels — 40 to 52 dB(A) — a COP claimed up to 16, three heating modes and Wi-Fi with voice control.
Best for: A 10–20 m³ pool close to a house, where the decibel range is the deciding figure
To 28 °C, no bypass needed, to 20 m³, R32
The only machine here stated to work without a bypass, and the only one that publishes a maximum water temperature of 28 °C rather than 40 — with a maker who recommends a summer cover at night in the same breath.
Best for: A 20 m³ pool where avoiding a bypass and its plumbing is worth more than a headline figure
3.5 kW, COP 5.5, to 15 m³, titanium exchanger, 24 kg
A 3.5 kW plug-in heat pump with a titanium heat exchanger stated resistant to chlorine and salt water, R32 refrigerant and a published weight of 24 kg.
Best for: A salt pool up to 15 m³, where the exchanger material is the reason for choosing
7 kW inverter, 30–45 m³, multi-frequency compressor, WiFi
A 7 kW inverter for 30–45 m³ whose entire feature list on this marketplace reads “bulletpoint1” and “bulletpoint2” — the template was published unfilled, and everything known about it comes from the title.
Best for: A 30–45 m³ pool where the maker is the reason and the documentation will be sought elsewhere
7.6 kW full inverter, COP to 12.8, 20–29 dB, 50 mm unions
A full-inverter machine for 30–45 m³ publishing the lowest noise figures on this shelf — 20 to 29 dB — and the only one that states its hydraulic connection size, at 50 mm.
Best for: A 30–45 m³ pool with rigid pipework, close enough to a house that noise decides it
6 kW inverter, COP to 9.38, to 20 m³, IPX4
A 6 kW inverter with a four-way valve for heating and cooling, an IPX4 rating, and a maker who states in the listing that reaching the target temperature can take several days.
Best for: A 20 m³ pool where the honesty about heat-up time is worth reading before buying
4.92 kW, COP 5.29, 10–18 m³, 32/38 mm, heats and cools
The best-specified mid-priced machine here: an output to two decimals, an ambient range from −5 °C, both hose diameters published with adapters, and a heating and a cooling range each given in full.
Best for: A 10–18 m³ pool where knowing what it plumbs into before ordering matters
7 kW inverter, COP to 16.2, 27 dB(A), R290, salt to 5 g/l
A 7 kW inverter using R290 refrigerant, rated to 27 dB(A), with the widest temperature windows on this shelf and a stated salt tolerance of 5 g/l — the only machine here to put a salinity figure in writing.
Best for: A salt pool up to 30 m³ where the salinity figure and the solar input both matter
Only the specifications at least four models out of five state. A column that is more empty than full compares nothing.
| Model | Price | Amazon reference | Connection size | COP | COP conditions |
|---|
Specifications: manufacturer sheets and Amazon product pages. Prices and availability: Keepa. No product on this site has been physically tested.
Most recent revision in this category: September 21, 2026.
