Poolex Nano FI Compact Full Inverter Heat Pump with Wi-Fi for Above-Ground Pools

Poolex Nano FI Compact Full Inverter Heat Pump with Wi-Fi for Above-Ground Pools

Ultra-compact, quiet and energy-efficient Full Inverter pool heating for small garden pools

The Poolex Nano FI Compact Full Inverter Heat Pump provides efficient, quiet and convenient heating for small above-ground swimming pools and compact garden pools. It combines the convenient plug-and-play format of the standard Poolex Nano with more advanced Full Inverter technology, allowing the compressor and fan to alter their speed according to the amount of heating your pool actually requires.

The Poolex Nano is suitable for many Bestway, Intex, framed, tubular, wooden and other above ground swimming pools, provided the filtration system can maintain the required water flow and can be connected using suitable 32mm or 38mm hoses.

This makes the Nano FI an excellent choice for pool owners who want more stable water temperatures, quieter operation and improved energy efficiency without installing a large conventional swimming pool heat pump.

The compact casing measures only 440mm x 430mm x 426mm, allowing the heater to sit neatly beside framed pools, wooden pools, seasonal pools, patios and decking areas. Despite its relatively small footprint, the range provides up to 3kW or 5kW of heating output, depending on the model selected.

Built-in 2.4GHz Wi-Fi allows you to monitor and control the heat pump using the Poolex mobile app. You can adjust the target temperature, switch between heating, cooling and automatic modes and check the heater without having to stand beside the pool.

Full Inverter heating for improved efficiency

A traditional On/Off heat pump normally runs at full output until the target temperature is reached and then switches off. When the water cools, the compressor starts again at full output.

The Poolex Nano FI works differently. Its Full Inverter system continuously adjusts the compressor and fan speed to match the pool’s heating requirements. It can operate at higher output when initially warming the pool before reducing its output as the water approaches the selected temperature.

Once the target temperature has been reached, the Nano FI can continue operating at a lower, more economical speed rather than repeatedly switching between full output and completely off.

This provides several practical advantages:

• More stable pool water temperatures
• Reduced temperature fluctuations
• Quieter operation at lower output
• Less abrupt compressor starting
• Improved efficiency when maintaining temperature
• More controlled energy usage throughout the day

Under favourable A26/W26 test conditions, the Nano FI 3 can achieve a COP between 6.74 and 9.0, while the Nano FI 5 can achieve a COP between 6.0 and 8.4, depending on the operating output.

COP will reduce as the outside air becomes colder, so real-world performance depends on the weather, pool volume, required water temperature, insulation, wind exposure and whether the pool is covered.

Poolex Nano FI or standard Poolex Nano?

The standard Poolex Nano and the Poolex Nano FI are both designed for small pools, but they use different compressor control systems.

The standard Nano is the lower-cost On/Off version. It is a sensible choice for customers who want straightforward, compact pool heating and expect to use the pool mainly during warmer weather.

The Nano FI is the premium Full Inverter version. It continuously regulates compressor and fan speed, making it better suited to customers who place greater importance on quiet operation, efficient temperature maintenance and more precise control.

For the lower-cost On/Off alternative, view the Poolex Nano Ultra Compact Heat Pump with Wi-Fi for Above-Ground Pools.

Feature	Standard Poolex Nano	Poolex Nano FI
Compressor control	On/Off	Full Inverter
Output control	Runs at fixed output	Continuously variable
Temperature maintenance	Starts and stops as required	Reduces output near the target
Noise at 10 metres	Under 30dB(A)	Under 35dB(A)
Wi-Fi control	Yes	Yes
Heating and cooling	Yes	Yes
Best suited to	Lower initial purchase price	Quieter and more efficient temperature maintenance

Two models for pools up to 30m³

The Poolex Nano FI range is available in two model sizes.

The Nano FI 3 produces up to 3kW of heating output and is recommended by Poolex for pools up to 20m³ in favourable conditions.

The Nano FI 5 produces up to 5kW and is recommended for pools up to 30m³ in favourable conditions.

Manufacturer pool volumes should be treated as upper limits rather than guaranteed UK sizing figures. Cooler air temperatures, exposed locations, uncovered pools and longer swimming seasons all increase the amount of heating required.

For a UK installation, choosing the larger model can provide quicker heating and better performance during cooler spring and autumn weather. A properly fitted solar or bubble cover will also make a substantial difference to heat retention and running costs.

Heating, cooling and automatic modes

The Poolex Nano FI is a reversible heat pump with three operating modes.

Heating mode raises the pool water towards your chosen temperature and then modulates the output to help maintain it.

Cooling mode can reduce excessive water temperatures during particularly hot weather.

Automatic mode allows the unit to manage heating or cooling according to the selected temperature.

The heating temperature range is adjustable between 10°C and 40°C, while the heat pump has a stated ambient operating range of -7°C to 43°C.

Although the heater can operate at lower air temperatures, its output and efficiency will reduce as the surrounding air becomes colder. Correct sizing remains especially important when the pool is expected to operate outside the main summer season.

Built-in Wi-Fi control

The Nano FI includes built-in 2.4GHz Wi-Fi connectivity and can be controlled through the Poolex app.

Once paired with your home network, the app allows you to:

• View the current pool temperature
• Adjust the target water temperature
• Select heating, cooling or automatic mode
• Switch the heat pump on or off
• Monitor operation remotely

The heater must be able to receive a stable 2.4GHz Wi-Fi signal at its outdoor installation position. It will not connect directly to a 5GHz-only network.

Quiet operation for small gardens

Compact swimming pool equipment is often installed close to patios, seating areas, neighbouring gardens or bedroom windows. The Poolex Nano FI has therefore been designed to operate discreetly.

The Nano FI 3 has a stated noise level of approximately 48dB(A) at one metre, while the Nano FI 5 is approximately 50dB(A) at one metre. Both models are rated at below 35dB(A) when measured from ten metres away.

Because Full Inverter technology allows the compressor and fan to slow down as the pool approaches its target temperature, normal temperature maintenance can be noticeably quieter than the initial heating period.

The heater should still be installed on a solid, level base with suitable clearance and unrestricted airflow. Avoid positioning it inside a shed, enclosed box or tightly confined equipment housing.

Plug-and-play pool installation

The Poolex Nano FI has been developed for straightforward installation on small domestic pools. UK-supplied units include a fitted mains cable and UK plug for connection to a suitable RCD-protected electrical supply.

The heat pump should not be operated through an unsuitable extension lead. Where a permanent electrical installation is preferred, any alteration or hardwiring should be completed by a suitably qualified electrician in accordance with the manufacturer’s instructions and current electrical regulations.

The water inlet and outlet connections are 32mm. Suitable hose tails allow the heater to be connected to common 32mm and 38mm flexible swimming pool hoses.

This makes it suitable for many:

• Framed above-ground pools
• Inflatable and tubular pools
• Wooden swimming pools
• Seasonal garden pools
• Small in-ground or partially in-ground pools
• Compact domestic swimming pools

Water flow and bypass installation

Correct water flow is important for reliable heat pump operation.

The Nano FI 3 requires a nominal flow of approximately 1.3m³ per hour, while the Nano FI 5 requires approximately 2.15m³ per hour.

Where the existing filtration system already produces a suitable flow, the heater can be installed directly into the pool return line. However, we strongly recommend using a swimming pool heat pump bypass kit where the filtration pump produces considerably more flow than the heat pump requires.

A bypass kit allows the amount of water passing through the heater to be adjusted while the remaining flow continues through the filtration return. It also makes it easier to isolate the heat pump for maintenance, cleaning and winterisation without dismantling the entire pool circulation system.

Depending on your current setup, additional 38mm swimming pool vac hose and stainless steel hose clips may also be required.

Titanium heat exchanger for treated pool water

The Poolex Nano FI uses a corrosion-resistant Twisted Tech titanium heat exchanger.

Titanium is well suited to swimming pool applications and allows the heater to be used with correctly maintained chlorine, salt, bromine and ozone-treated pool water.

Correct water chemistry must still be maintained. Excessive chlorine levels, incorrect pH, concentrated chemicals passing directly through the heater or poorly positioned chemical dosing equipment may damage the pool system.

Where an automatic chlorinator, salt chlorinator or chemical dosing system is installed, it should normally be positioned after the heat pump in the circulation line and installed in accordance with the equipment manufacturer’s instructions.

Automatic defrost for cooler conditions

Automatic defrost helps clear frost from the evaporator during colder operating conditions.

When frost is detected, the Nano FI temporarily changes its operating cycle to clear the evaporator before returning to normal heating. This helps protect airflow and allows the heater to continue operating during cooler spring and autumn conditions.

Automatic defrost does not remove the need to winterise the unit. Any residual pool water must be drained from the heat exchanger when the heater is not being used and there is a risk of freezing.

Frost damage caused by water freezing inside the heat exchanger is not normally covered by the manufacturer’s warranty.

Pool covers and insulation

A swimming pool cover is strongly recommended whenever a heat pump is being used.

A significant amount of pool heat is lost through evaporation from the water surface, especially overnight or during windy weather. A solar cover or bubble cover reduces evaporation and helps retain the heat already transferred into the pool.

Above-ground pools can also lose heat through their walls and base. Where practical, adding suitable insulation beneath and around the pool can further reduce heat loss.

Good heat retention can:

• Reduce the time needed to warm the pool
• Lower heat pump running time
• Improve temperature stability overnight
• Extend the usable swimming season
• Improve performance during cooler weather

Positioning the Nano FI

The Poolex Nano FI must be installed outside in a position with unrestricted airflow.

The rear evaporator draws in large volumes of outside air, while the front fan discharges cooled air after heat has been transferred into the pool water. Restricted airflow can reduce heating performance and may cause the air discharged by the unit to circulate back through the evaporator.

Place the heater on a firm and level base, allowing the clearances stated in the installation manual around the air inlet, fan outlet and service areas.

For an above-ground pool, the heat pump can normally sit at ground level beside the pool. It does not usually need to be raised above the waterline simply because the pool itself is above ground.

Condensation is normal during operation. Water may drip beneath the heater as moisture condenses on the cold evaporator, particularly during humid weather. Suitable drainage should therefore be allowed around the installation area.

 

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Key Benefits

• Full Inverter compressor and variable-speed fan control
• Available in 3kW and 5kW model options
• Recommended for pools up to 20m³ or 30m³ in favourable conditions
• Compact design for patios and small gardens
• Suitable for above-ground, framed and wooden pools
• Built-in 2.4GHz Wi-Fi connectivity
• Remote control through the Poolex app
• Heating, cooling and automatic operating modes
• COP of up to 9.0 under favourable test conditions
• Quiet operation below 35dB(A) at ten metres
• 32mm water connections
• Compatible with common 32mm and 38mm pool hoses
• Twisted Tech titanium heat exchanger
• Suitable for correctly maintained chlorine and saltwater pools
• Automatic defrost for cooler conditions
• R32 refrigerant
• Simple plug-and-play style installation
• Bypass kit available for flow regulation and isolation

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Reasons to Buy

The Poolex Nano FI is ideal for customers who want the convenience of a compact above-ground pool heater but would prefer the smoother and more efficient operation of a Full Inverter system.

Rather than repeatedly starting and stopping at full power, the heater can reduce its output as the pool approaches the selected temperature. This helps maintain more consistent water temperatures while reducing unnecessary noise and energy use.

Its compact dimensions make it suitable for smaller gardens where a conventional pool heat pump would be too large or intrusive. Wi-Fi control makes it easy to check and adjust the heater remotely, while the reversible heating and cooling system provides greater control throughout the swimming season.

For customers comparing the two compact Poolex models, the standard Nano remains the lower-cost choice. The Nano FI is the better option where quieter temperature maintenance, inverter efficiency and more advanced output control are priorities.

What Is Included?

• Poolex Nano FI Full Inverter Heat Pump
• UK mains cable and plug
• 32mm and 38mm hose connectors
• Installation and operating instructions

Recommended Extras

• Above-ground pool heat pump bypass kit
• 38mm swimming pool vac hose
• Stainless steel hose clips
• Solar or bubble pool cover
• Suitable pool wall and base insulation
• Additional hose fittings where required

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Technical information

Specification	Nano FI 3	Nano FI 5
Manufacturer reference	PC-NANO-B3N	PC-NANO-B5N
Recommended pool volume*	Up to 20m³	Up to 30m³
Heating output at A26/W26	1.56–3.00kW	2.20–5.00kW
Power consumption at A26/W26	0.18–0.45kW	0.21–0.83kW
COP at A26/W26	6.74–9.0	6.0–8.4
Heating output at A15/W26	1.05–2.45kW	1.56–3.50kW
Power consumption at A15/W26	0.15–0.57kW	0.20–0.81kW
COP at A15/W26	4.31–5.06	4.30–5.00
Maximum power input	1.5kW	2.1kW
Electrical supply	220–240V, single phase	220–240V, single phase
Heating temperature range	10°C–40°C	10°C–40°C
Ambient operating range	-7°C–43°C	-7°C–43°C
Nominal water flow	1.3m³/h	2.15m³/h
Water connection	32mm	32mm
Compatible flexible hose	32mm and 38mm	32mm and 38mm
Refrigerant	R32	R32
Noise at one metre	48dB(A)	50dB(A)
Noise at ten metres	Below 35dB(A)	Below 35dB(A)
Dimensions	440 x 430 x 426mm	440 x 430 x 426mm
Net weight	26kg	30kg
Compressor	GMCC Full Inverter	GMCC Full Inverter
Heat exchanger	Twisted Tech titanium	Twisted Tech titanium
Operating modes	Heating, cooling and automatic	Heating, cooling and automatic
Wi-Fi	Built-in 2.4GHz	Built-in 2.4GHz
App control	Poolex app	Poolex app

Available model options

For easier comparison, the main model options are shown below with their key output and electrical input figures. Heat pump performance always depends on the test condition shown, so compare the same A/W condition when choosing between models.

• Nano 3.5 – SKU 118274-118275
  Output A26/W26: 3.25kW
  Input A26/W26: 0.59kW
  COP A26/W26: 5.5
• Nano 5.5 – SKU 118274-118276
  Output A26/W26: 5.0kW
  Input A26/W26: 0.93kW
  COP A26/W26: 5.4

Warranty Information

The Poolex Nano range includes comprehensive manufacturer warranty coverage:

• Heat Pump: 2 years
• Compressor: 5 years
• Titanium Coil: 15 years against chemical corrosion

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Important Notes

Poolex Nano FI 3

Manufacturer reference: PC-NANO-B3N
GTIN / EAN: 3700691422040
Maximum heating output at A26/W26: 3.0kW
Recommended pool volume: Up to 20m³ in favourable conditions
Nominal water flow: 1.3m³/h
Maximum power input: 1.5kW

Poolex Nano FI 5

Manufacturer reference: PC-NANO-B5N
GTIN / EAN: 3700691422057
Maximum heating output at A26/W26: 5.0kW
Recommended pool volume: Up to 30m³ in favourable conditions
Nominal water flow: 2.15m³/h
Maximum power input: 2.1kW

Warranty Information

The Poolex Nano FI is supplied with the following warranty package, subject to the manufacturer’s terms and correct installation, operation and winterisation:

• Complete heat pump: 2 years
• Compressor: 5-year parts warranty
• Titanium heat exchanger: 15-year parts warranty against chemical corrosion

Warranty cover applies to manufacturing defects. Labour, incorrect installation, unsuitable water chemistry, restricted airflow, frost damage and failure to drain the heater during freezing conditions may not be covered.

Important Notes

The Poolex Nano FI must be installed outside with sufficient airflow around the evaporator and fan.

Do not install the heat pump inside an enclosed shed, cabinet or unventilated plant room.

Connect the heater to a suitable RCD-protected electrical supply and do not use an unsuitable extension lead.

The Nano FI 3 requires approximately 1.3m³/h of water flow. The Nano FI 5 requires approximately 2.15m³/h.

A bypass kit is recommended where filtration flow requires adjustment or where isolation is wanted for maintenance and winterisation.

Manufacturer pool volume recommendations are based on favourable conditions and may be optimistic for an exposed UK pool.

Use a pool cover whenever possible to reduce evaporation and heat loss.

Maintain correct pool water chemistry and install chemical dosing equipment in accordance with the relevant manufacturer’s instructions.

Drain all residual water from the heat exchanger when the heat pump is not being used and freezing temperatures are possible.

Wi-Fi control requires access to a stable 2.4GHz wireless network.