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ESBE pump groups: how they work and how to choose the right type
A pump group is used wherever heating water needs to be distributed from a heat source – a boiler, heat pump or buffer tank – to a heating circuit, while also controlling its temperature if required. You will typically find it between the heat source and underfloor heating, where the mixing valve maintains a safe flow temperature, between a boiler and a radiator circuit with weather-compensated control, or for charging a buffer tank. It is a pre-assembled and tested unit: the pump, isolating valves with thermometers, check valve and, in mixing versions, a three-way valve are all housed within a single insulation shell that the installer simply connects up. There is no need to assemble individual components, installation is quicker, and the unit comes with manufacturer-guaranteed performance parameters.
A single pump group serves one heating circuit – it is chosen where a house has only one circuit, or where several circuits are connected to a common manifold and each circuit has its own group. For two circuits, ESBE also offers twin groups that integrate both circuits, including the manifold, into a single block. In this article, we will focus on ESBE single pump groups – the direct GDA series, the thermostatic GFA series and the mixing GRA series, which differ mainly in how they handle the temperature of the heating water.
What a pump group includes
The basic equipment of ESBE single pump groups is the same across all series: two isolating valves with colour-coded thermometers (flow and return), a check valve on the heating circuit return to prevent gravity circulation, a high-efficiency circulating pump, and an EPP thermal insulation shell. Wall mounting is made easier by an adjustable bracket. The groups can also be fitted to ESBE GMA series manifolds, which are supplied either with or without an integrated hydraulic separator. All three series are available in DN20, DN25 and DN32 sizes, with Wilo PARA or Grundfos UPM3 AUTO pumps with an energy efficiency index of EEI < 0.20 and < 0.21 respectively.
GDA200 and GDA300 – direct groups for heat transfer
The GDA200 (DN25 and DN32) and GDA300 (DN20) series are direct, non-mixing groups. They do not contain any control valve – they simply transfer heating water efficiently wherever its temperature is not adjusted in that section. Typical applications include heat transfer between a boiler and a manifold, charging a buffer tank, or a radiator circuit whose temperature is controlled directly by the heat source. Available versions include the GDA211 with Wilo PARA 25/6 and 25/8 pumps, the GDA212 with Grundfos UPM3 AUTO 25-50 and 25-70 pumps, and the compact GDA311 (DN20, Wilo PARA STG 15/8).
GFA200 and GFA300 – thermostatic groups for constant temperature
The GFA200 and GFA300 series additionally feature a three-way thermostatic mixing valve with an adjustable temperature range of 20–55 °C. The valve mixes return water into the flow and maintains the set temperature without an electric actuator and without an external controller – control is purely thermostatic. According to the manufacturer, these groups are intended for systems where the heat source does not have its own controller, or only has a controller with limited functions, and where a constant flow temperature is required – typically simpler underfloor heating installations. Available versions: GFA211 (Wilo, DN25/DN32), GFA212 (Grundfos, DN25/DN32) and GFA311 (DN20, VTA378 valve).
GRA200 and GRA300 – mixing groups for weather-compensated control
The GRA mixing series is designed for circuits where the flow temperature is controlled by an external controller – most commonly a weather-compensated controller, which calculates it according to the outdoor temperature and the set heating curve. The group is equipped with a VRG432 three-way rotary valve (VRG438 on the GRA311) with a progressive flow characteristic and an electric actuator. The progressive characteristic ensures good controllability in various system combinations (high-temperature heat source, low-temperature heating surface), reduces control oscillation and, because of this, one valve size covers a wider output range, reducing the risk of oversizing.
The choice of specific version depends mainly on the controller output: the GRA211 and GRA212 have an ARA661 actuator with a three-point control signal and 230 V AC power supply (running time 120 s), while the GRA231 and GRA232 have an ARA639 actuator for modulating (proportional) control with a 24 V supply. Versions with index 1 (GRA211, GRA231) have Wilo PARA 25/6 or 25/8 pumps, while versions with index 2 (GRA212, GRA232) have Grundfos UPM3 AUTO 25-50 or 25-70 pumps; all are available in DN25 and DN32. For smaller circuits, the GRA311 in DN20 is intended, with a Wilo PARA STG 15/8 pump and ARA661 actuator. The actuator is fitted to the valve using the tool-free QuickFit interface. The range is complemented by the GBA211 bivalent group, intended for circuits requiring flow temperature control and efficient use of energy from two heat sources.
How to choose the right pump group
The key factor is the method of temperature control. If the temperature in the given section is not controlled, a direct GDA group is sufficient. If the flow temperature needs to be constant and there is no controller in the system to manage it, choose a thermostatic GFA group with a 20–55 °C range. If the temperature is controlled by a weather-compensated or other external controller, the circuit requires a GRA mixing group – with an ARA661 actuator for controllers with a 230 V three-point output, or with an ARA639 actuator for a proportional signal. The size (DN20, DN25, DN32) is selected according to the circuit output and required flow rate; the manufacturer provides sizing data in the technical datasheets for the individual series.
Comparison of ESBE pump group variants
| Parameter | GDA200 / GDA300 | GFA200 / GFA300 | GRA200 / GRA300 |
|---|---|---|---|
| Function | direct (without temperature control) | thermostatic mixing, constant temperature | mixing controlled by an external controller |
| Control valve | – | thermostatic valve, 20–55 °C | VRG432/VRG438 rotary valve + ARA661 / ARA639 actuator |
| Size | DN20, DN25, DN32 | DN20, DN25, DN32 | DN20, DN25, DN32 |
| Pressure class | PN 10 (1.0 MPa) | PN 10 (1.0 MPa) | PN 10 (1.0 MPa) |
| Medium temperature | +5 to +100 °C (GDA212 up to +110 °C) | +5 to +100 °C | +5 to +100 °C (GRA212/232 up to +110 °C) |
| Pump | Wilo PARA / Grundfos UPM3 AUTO | Wilo PARA / Grundfos UPM3 AUTO | Wilo PARA / Grundfos UPM3 AUTO |
| Insulation | EPP λ 0.036 W/mK | EPP λ 0.036 W/mK | EPP λ 0.036 W/mK |
What to watch out for in design and operation
The heating water must comply with the requirements of VDI 2035. A water-glycol mixture of up to 50% may also be used as the medium, but glycol affects pump performance, so the pump parameters must be checked for such applications. The ambient temperature should be within the range of 0 to +55 °C. Both the pump and the actuator must be preceded in the fixed electrical installation by a multipole isolator. Under normal operating conditions, ESBE pump groups do not require any special maintenance; a routine leak-tightness check as part of regular heating system servicing is recommended.
Frequently asked questions
A direct group (e.g. GDF200) simply transfers heating water from the heat source to the circuit without changing its temperature. A mixing group (e.g. GRA100) additionally includes a three-way valve with actuator, which mixes return water into the flow and thus enables smooth control of the heating water temperature in the circuit – for example according to a weather-compensation curve.
That depends on the system design. For standalone groups, ESBE offers GMA series manifolds both with and without an integrated hydraulic separator. The DAA100/DDA100 twin groups have hydraulic separation integrated directly into the unit manifold, and it is activated simply by means of an adjusting screw.
The ARA661 actuator operates with a 230 V AC three-point control signal, so the group can be connected to most weather-compensated and system controllers available on the market that provide this output.
The GDF200 series is specifically designed for this – it is supplied without a pump and is prepared for standard circulating pumps with an installation length of 180 mm. The other series mentioned are supplied with a fitted Grundfos or Wilo pump; the pumps are also available as spare parts.
Yes. The DVA111 kit (order no. 66100300) adds a mixing valve with actuator to the direct branch, turning the DDA111 unit into a fully featured DAA111 with two mixed circuits.
Heating water compliant with VDI 2035, or alternatively a water-glycol mixture of up to 50% (if the glycol content exceeds 20%, the pump data must be checked). For the GRA100 series, a water-ethanol mixture of up to 28% is also permitted.
