Ground/water heat pump Thermia LEGEND 4 (BW LEGEND 4) – 4 kW, output up to 60 °C, 184 l DHW tank

Product detailed description

Compact heat source for a family house

LEGEND 4 is the smallest model in the Thermia LEGEND ground/water (BW) heat pump range, continuing the proven Thermia Diplomat. In one cabinet with dimensions 598 × 703 × 1863 mm, it hides a refrigeration circuit with a Copeland scroll compressor, circulation pumps, a three-way valve for heating/hot water, a three-stage electric booster 3/6/9 kW, and a stainless steel hot water tank 184 l with TWS technology. It draws heat from a ground collector or borehole and delivers water up to 60 °C to the heating system – suitable for underfloor heating and radiators.

Performance and efficiency

• heating output 4.71 kW and COP 4.30 at B0/W35 according to EN 14511
• energy class A+++ for underfloor heating (35 °C), A++ for radiators (55 °C), and A for hot water heating
• refrigerant R452B (0.575 kg), compressor with soft starter, classic on/off control
• stainless steel plate heat exchangers and electronic circulation pumps of class A
• sound power level 40 dB(A)

Control and extensions

The control unit with a graphic display sets the temperature of the heating water equithermally according to the outside temperature, hot water preparation has priority over heating. The SMART GRID function allows cooperation with photovoltaics, and optionally remote control and monitoring via the internet are also available. With additional accessories, it can handle a mixed heating circuit, pool heating, and cooling.

Design and installation

The pump is powered by 400 V 3-N, 50 Hz. For dimensioning, the manufacturer prescribes the HPC calculation software; in the heating system, at least 14 l of water per kW of power must be ensured. The primary circuit is filled with a mixture of water and ethanol with a freezing point of -17 ±2 °C. Installation, electrical connection, and commissioning must be performed by a professional company.

Technical parameters

Frequently asked questions

What is included in the delivery?
In addition to the heat pump, brine pipe with fittings, safety valve 9 bar for hot water, safety valve 3 bar for the antifreeze circuit, external sensor, ball valve with filter, and brine filling device are included. The safety valve for the heating system is not part of the delivery.

How long can the ground collector be?
The built-in brine pump in LEGEND 4 can handle one collector with a total length of up to 1000 m (PEM DN 40, calculation for ΔT 4 K). The required length for a specific house is determined by the design in the HPC software.

Can the pump heat and heat water at the same time?
No, heating and hot water heating alternate, and hot water preparation has priority. The 184 l tank is built directly into the pump cabinet.

Can LEGEND 4 be connected to 230 V?
No, the LEGEND 4 model is powered only by 400 V 3-N, 50 Hz. A version for 230 V is available only for the LEGEND 8 and 10 models according to the manufacturer.