Kensa Shoebox NX

Shoebox NX is Kensa’s current compact ground source heat-pump family. It has 3 kW and 5 kW single-phase models for individual ground arrays or ambient shared-loop systems. Both units fit the same 627 mm high, 554 mm wide and 570 mm deep casing.

Two different units

The 3 kW S3NX-P0K has a rated output of 2.85 kW at B0/W35 and a coefficient of performance of 4.40. The 5 kW S5-P0K-NX is rated at 5.8 kW at the same condition with a COP of 4.36.

Their average-climate SCOP figures at 35°C are 4.53 and 4.60 respectively. The broader headline SCOP figures elsewhere on Kensa’s page use different source conditions, so the test basis belongs with any comparison.

Technical differences

The two models do not share a refrigerant. The 3 kW unit uses R134a with a 0.725 kg charge, while the 5 kW uses R407C with a 1.1 kg charge. Maximum flow temperature is 65°C for the 3 kW and 64°C for the 5 kW.

Dry weights are 86 and 93 kg. Published sound power is 40.5 dB(A) for the 3 kW and 51.2 dB(A) for the 5 kW. Both require a 220 to 240 V single-phase supply, but their running currents, source flows and pressure drops differ.

System context

Shoebox NX contains no backup immersion heater. It provides heat to the space-heating circuit and a separate hot-water cylinder. Passive cooling is available only with the required hydraulic arrangement and controls.

Both models are marked Connect & Notify approved in Kensa’s technical table. They also have separate MCS certificate references: BBA 0055/46 for S3NX-P0K and BBA 0055/45 for S5-P0K-NX.

For heat pumps sold after 1 February 2026, Kensa’s current warranty structure applies subject to registration, installer eligibility and its full terms.

Related entries

• Kensa
• Shoebox
• Shared ground-loop systems
• Domestic hot-water cylinders