Thermia LEGEND 4 ground source heat pump (BW LEGEND 4) – 4 kW, flow up to 60 °C, 184 l DHW cylinder

Product detailed description

Compact heat source for a family home

LEGEND 4 is the smallest model in Thermia's LEGEND range of ground source (BW) heat pumps, which follows on from the proven Thermia Diplomat. A single 598 × 703 × 1863 mm cabinet houses the refrigerant circuit with a Copeland scroll compressor, the circulation pumps, the heating/hot water diverter valve, a three-stage 3/6/9 kW electric back-up heater and a 184 l stainless steel hot water cylinder with TWS technology. Heat is drawn from a ground collector or borehole, and water at up to 60 °C is delivered to the heating system – suitable for underfloor heating and radiators alike.

Output 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
• R452B refrigerant (0.575 kg), compressor with soft starter, classic on/off control
• stainless steel plate heat exchangers and class A electronic circulation pumps
• sound power level 40 dB(A)

Controls and extensions

The control unit with graphic display sets the heating water temperature according to the outdoor temperature, and hot water production takes priority over heating. The SMART GRID function allows it to work with a photovoltaic system, and remote control and monitoring via the internet are available as an option. With extension accessories it can also handle a mixed heating circuit, pool heating and cooling.

Sizing and installation

The heat pump runs on 400 V 3-N, 50 Hz. For sizing, the manufacturer requires the HPC calculation software; the heating system must contain at least 14 l of water per kW of output. The primary circuit is filled with a water-ethanol mixture with a freezing point of -17 ±2 °C. Installation, electrical connection and commissioning must be carried out by a specialist contractor.

Technical data

Frequently asked questions

What is included in the delivery?
Besides the heat pump: brine pipes with couplings, a 9 bar safety valve for hot water, a 3 bar safety valve for the brine circuit, an outdoor sensor, a ball valve with filter and a brine filling device. The heating system safety valve is not included.

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

Can the heat pump heat the house and hot water at the same time?
No, space heating and hot water production alternate, and hot water takes priority. The 184 l cylinder is built directly into the heat pump cabinet.

Can the LEGEND 4 be connected to 230 V?
No, the LEGEND 4 runs only on 400 V 3-N, 50 Hz. The manufacturer lists a 230 V version only for the LEGEND 8 and 10 models.