Vaillant auroFLOW exclusive VPM 20/2 S - solar module (pressurized system)

Product detailed description

Vaillant auroFLOW exclusive VPM 20/2 S – solar module for pressurized solar systems

The Vaillant auroFLOW exclusive VPM 20/2 S solar module (manufacturer order number 0010015139) is a compact solar charging station that transfers heat from roof-mounted solar collectors to a heating water storage tank (typically the Vaillant allSTOR exclusive) in a pressurized (classic, glycol) solar circuit. Instead of a distributed solar control system made up of a separate solar pump, controller, safety group and expansion vessel, the auroFLOW exclusive integrates all these components into a single compact module with its own display and full communication with the rest of the Vaillant heating system.

The designation "20" in the model line indicates that this module is intended for solar collector arrays with an area of approximately 4 to 20 m² of auroTHERM flat solar collectors – suitable for typical family homes with solar-assisted hot water preparation, or partial solar heating support. For larger collector arrays (from 20 to 60 m², typically for apartment buildings or commercial applications), the higher-capacity VPM 60/2 S module is intended.

How a pressurized solar system works

In a pressurized (classic) solar system, a mixture of water and non-freezing solar fluid (glycol) circulates in the collector circuit, kept under constant pressure by an expansion vessel and safety group integrated directly in the module. The solar pump in the module transports the heated heat transfer fluid from the collectors through a plate heat exchanger to the storage tank, where it transfers heat to the water intended for domestic hot water preparation or heating support. The module continuously evaluates the temperature at the collectors and in the storage tank, and starts the pump only when the temperature at the collectors is higher than in the storage tank by a set value (so-called differential control), which maximizes the use of solar energy while preventing unnecessary pump operation.

The module is equipped with an illuminated graphic display that continuously shows the current solar yield, temperatures at the collectors and in the storage tank, and the system's operating status. This gives both the user and the service technician an immediate overview of how much energy the system is actually gaining from the sun.

Integrated components

The auroFLOW exclusive VPM 20/2 S module combines:

• A high-efficiency solar circulation pump with electronically controlled speed that adapts to the current intensity of solar radiation.
• A plate heat exchanger for transferring heat from the solar circuit to the storage tank.
• An integrated differential solar controller with an illuminated display.
• A safety group with pressure gauge and fill/drain valve for the solar circuit.
• A three-way switching valve for controlling the flow of the heat transfer fluid (e.g. in a cascade connection of two modules).
• Temperature and flow sensors for precise evaluation of solar yield.

Thanks to this integration, there is no need to separately size, procure and connect individual components of the solar system, which significantly simplifies both design and installation.

Installation and mounting options

Like the aguaFLOW fresh water modules, the auroFLOW exclusive solar module can be mounted either directly on the storage tank (typically the allSTOR exclusive) using a "plug & play" quick-coupling system, or separately on a wall connected to the storage tank via heating/solar piping. The delivery also includes a power cable approximately 4 meters long and a set of adapters with sealing rings for connection to the storage tank, as well as seals for connecting the solar circuit.

Cascade connection

For larger solar arrays exceeding the capacity of a single module, or when it is necessary to divide the collector array into several independently controlled branches, up to two auroFLOW exclusive modules can be connected in a cascade using the integrated three-way valve, which ensures proper distribution of the heat transfer fluid flow between the individual units.

Technical characteristics

Compatibility and recommended setup

The auroFLOW exclusive VPM 20/2 S module is designed primarily to work together with the allSTOR exclusive layered storage tank and auroTHERM series solar flat collectors. It is common for the aguaFLOW exclusive fresh water module, connected to the same storage tank, to work alongside it – the solar module continuously recharges the storage tank with heat from the sun, while the fresh water module transfers this heat to the hot water distribution at the moment of consumption. The entire system is controlled by a higher-level Vaillant system controller (e.g. sensoCOMFORT 720) via the eBUS bus, which coordinates solar yield, backup heating by the boiler or heat pump, and hot water preparation as a single logical unit.

Advantages of an integrated solar module compared to a classic setup of individual components

• Simpler design and installation – one compact unit instead of a separate pump, controller, safety group and expansion vessel.
• Clear diagnostics – the illuminated display directly shows solar yield and operating status without the need for a separate measuring device.
• Full integration with the Vaillant system – communication via eBUS simplifies coordination with the rest of the heating system.
• Space savings in the boiler room – compact dimensions and the option of direct mounting on the storage tank.
• Scalability – the option of a cascade connection when expanding the collector array.

Installation recommendations

Installation of the solar module, including connecting the solar circuit, filling it with heat transfer fluid (glycol mixture) and setting the differential control parameters, must be carried out by a qualified technician trained on Vaillant solar systems. Commissioning also includes checking the pressure in the solar circuit, the function of the safety valve, and setting the correct temperature differentials between the collectors and the storage tank according to the specific size of the collector array and the orientation of the roof.

Maintenance

Solar systems with a pressurized circuit require regular inspection, which should be part of the annual service check:

• checking the pressure in the solar circuit and the condition of the expansion vessel,
• checking the concentration and condition of the non-freezing heat transfer fluid (glycol gradually degrades and needs to be replaced after a certain number of years of operation),
• function of the safety valve and pressure gauge,
• operation of the solar pump and its noise level,
• function of the temperature sensors and accuracy of the displayed solar yield.

Why choose this model

For a typical family home with a medium-sized roof suitable for installing 4 to 20 m² of solar collectors, the auroFLOW exclusive VPM 20/2 S represents a comprehensive and technically advanced solution that combines solar yield with high operating comfort and easy integration into an existing Vaillant heating system. Thanks to the integrated solution instead of several separate components, the risk of installation errors is also reduced, and the time needed to commission the system is shortened.

Frequently asked questions

Solar system commissioning procedure

Commissioning of the auroFLOW exclusive VPM 20/2 S module involves several steps that must be performed by a qualified technician experienced with solar systems:

1. Checking the hydraulic connection of the solar circuit (flow and return to the collectors) as well as the storage tank side.
2. Filling the solar circuit with a suitable mixture of non-freezing heat transfer fluid (glycol) and water in the prescribed ratio, including thorough venting of the entire circuit, including the roof collectors.
3. Setting the pressure of the solar circuit to a value corresponding to the height and length of the piping route to the collectors, taking into account the capacity of the expansion vessel.
4. Electrical connection and communication of the module with the heat source and system controller via the eBUS bus.
5. Setting the differential control – the temperature difference at which the pump starts and stops, as well as protective functions against storage tank overheating.
6. Functional test – verifying correct pump operation, any cascade switching, and the solar yield values displayed on the screen.

Factors affecting actual solar yield

Even with a technically flawlessly installed auroFLOW exclusive VPM 20/2 S module, the actual solar yield depends on several factors beyond the module itself:

• Roof orientation and tilt – optimal south-facing orientation with a tilt corresponding to the geographic latitude brings the highest annual yield.
• Shading of collectors – even partial shading for part of the day (chimneys, trees, neighboring buildings) can significantly reduce the overall solar yield.
• Properly sized storage tank – a storage tank that is too small will not allow full use of the potential solar yield, while one that is too large extends the time needed to heat it.
• Household consumption profile – households with a more even hot water consumption throughout the day can use solar yield more efficiently than households with a single short intensive consumption period.

Safety aspects of a pressurized solar system

Since the heat transfer fluid in a pressurized solar circuit can reach high temperatures under strong solar radiation and insufficient heat consumption, the integrated safety group with a safety valve is a key safety feature of the module. If the maximum operating pressure is exceeded, the safety valve releases some of the fluid outside the circuit, preventing damage to the piping or system components. This is why regular inspection of the function of this safety group is part of every professional service check of the solar system.

Summary

The Vaillant auroFLOW exclusive VPM 20/2 S is a modern integrated solar module for pressurized solar systems in family homes, which simplifies the design, installation and operation of solar-assisted hot water preparation. Thanks to the compact solution combining all necessary components in one module and full integration into the Vaillant system, it represents a reliable investment in the use of solar energy.