Direct heat, priced in kilowatt-hours rather than in COP
This shelf holds the heaters that make their own heat rather than moving it: electric flow heaters, immersion elements, and the stainless wood-fired barrels that sit beside a pool with a coil in them. They share one honest property — every kilowatt of heat costs a kilowatt of energy, with none of the multiplication a heat pump offers — and one practical advantage: they work at any air temperature, and they heat far faster. The figure to read first is the power in watts, 2 000 to 3 000 W being common for an immersion type, because it sets both the rate of heating and the circuit it needs; anything above about 3 000 W on a single 230 V line is close to the limit of a domestic socket. The second is the flow rate a flow heater requires, because an electric element with insufficient water over it trips or fails — which is why the flow switch and the over-temperature cut-out are the two safety devices worth confirming by name rather than assuming. In wood-fired heaters the equivalent figure is the coil material and wall thickness: stainless throughout, or stainless skin on a mild steel coil. Then connection size, 32 or 38 mm, which decides whether it drops into an existing hose run. And the thermostat, which on this shelf ranges from a bimetal dial to nothing at all. We compare power, required flow, thermostat and cut-outs, materials, connection size and stated heat-up rate.
3 000 W for inflatable pools — nothing else published
A 3 000 W electric heater for inflatable pools with a thermometer and stated water-electricity separation. Five bullets say fast, effective, durable, safe and easy, and publish no figure of any kind.
Best for: An inflatable pool where the alternative is no heating at all
2 800 W, 1 520–17 035 l, 0.5–1.5 °C, GS by TÜV Rheinland
The best-specified electric heater here: 2 800 W for pools of 1 520 to 17 035 litres, a published heat-up rate of 0.5 to 1.5 °C, a 40 °C ceiling, a flow sensor, an RCD and GS certification from a named body.
Best for: A frame pool under 17 000 litres on a filter moving less than 3 785 l/h
60 kW exchanger, 304 stainless, no electrical connection
A 60 kW heat exchanger with no electrical connection: 55 GPM of pool water against 6.6 GPM of hot water, 200 000 Btu/h at a 60 °C difference. It transfers heat from a boiler or solar circuit and generates none.
Best for: A pool beside a house with spare boiler capacity or a solar thermal array already installed
9 kW of four grades, 20–55 °C, max 10 m³, self-wiring
An electric flow heater sold at 9 kW from a range of 5.5, 9, 11 and 15 kW, with a 20 to 55 °C thermostat and a maximum pool of 10 m³. The listing states the buyer must wire it themselves.
Best for: A hot tub or small pool where 55 °C is wanted and an electrician is already on site
60 kW, V4A / 316L, 10 bar tested, PED 2014/68/EU
A 60 kW heat exchanger in V4A / AISI 316L with no electrical connection, pressure-tested at 10 bar on the pool circuit and 5 bar on the heating circuit, and stated to meet the Pressure Equipment Directive.
Best for: A properly plumbed plant room where an installer is fitting it to an existing heat source
105.5 kW, 30 tubes, 0.69 m², 1.0 MPa, 316 stainless
The largest exchanger here at 105.5 kW — 360 000 BTU/h — with 30 capillary tubes, 0.69 m² of transfer area, a 1.0 MPa pressure rating and a stated −28 to 110 °C operating range.
Best for: A large pool or a commercial installation with a heat source already sized to match
60 kW, 250 L/min pool, 30 L/min hot, bellows, no power
A 60 kW heat exchanger published at 250 L/min pool flow and 30 L/min hot water — the same figures as another exchanger on this shelf. It states stainless steel without naming the grade.
Best for: A pool or sauna already served by a boiler, where the installer will specify the plumbing
3 000 W, to about 35 °C, pools to Ø 457 cm
A 3 000 W in-line electric heater for round Easy Set and plastic frame pools up to Ø 457 cm, heating to about 35 °C, with an integrated flow sensor.
Best for: A round Intex pool up to 457 cm already running an Intex filter line
15 kW for 10 m³, 20–50 °C, two cut-outs, not for salt water
The largest electric heater here at 15 kW, sized to 10 m³, with a touchscreen, two published protection mechanisms and an explicit statement that it must not be used in salt, acidic or alkaline water.
Best for: A freshwater spa or small pool up to 10 m³ where 15 kW of output is genuinely wanted
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 | Cut-outs | Power |
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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.
