Vaillant hydraulic connection kit boiler – cylinder VIH R 120, with safety group, temperature sensor and siphon

Product detailed description

Vaillant hydraulic connection between the boiler and the VIH R 120 cylinder, with safety group, temperature sensor and siphon

This Vaillant hydraulic connection kit provides a complete link between the ecoTEC plus wall-mounted condensing boiler and the external VIH R 120 domestic hot water cylinder (120-litre capacity) as a single, clearly arranged, manufacturer-designed unit. Instead of assembling the connection from individual separate parts (piping, fittings, sensor, safety group, siphon) from various suppliers, this kit offers all the necessary components precisely matched to one another, which significantly simplifies and speeds up installation for the plumbing company and also reduces the risk of an incorrect combination of component parameters.

Why a 120-litre cylinder is a common choice

The VIH R 120 cylinder with a capacity of 120 litres represents the mid-range category in Vaillant's cylinder lineup and is a common choice for households of two to four people, or for a smaller family house with one bathroom and average hot water consumption. This capacity is generally sufficient to cover the morning peak (simultaneous showering and kitchen use) without having to wait for reheating, as the boiler continuously replenishes the energy drawn from the cylinder throughout the day. When combined with a powerful condensing boiler from the ecoTEC plus range, this set achieves a fast rise to the required temperature thanks to the option of briefly increased burner output specifically when reheating the cylinder.

What the kit includes

The kit includes hydraulic connecting piping between the boiler outlets and the corresponding connections of the VIH R 120 cylinder, a safety group protecting the cylinder against exceeding the operating pressure, a cylinder water temperature sensor (ensuring communication between the cylinder and the boiler controller so the boiler knows when and with what intensity to reheat the cylinder), and a siphon for the safe and hygienic drainage of any water from the safety valve or condensate to the drain. This combination of components in a single kit guarantees that all parts are mutually compatible in terms of both dimensions and operating parameters.

Importance of the integrated temperature sensor

The temperature sensor placed in the cylinder's immersion sleeve is a key element for the correct functioning of the entire system – it informs the boiler control of the current water temperature in the cylinder, based on which the boiler decides when to switch to hot water preparation mode and at what intensity. Without a properly functioning and correctly fitted sensor, the control system would not have reliable information about the cylinder's charge status, which could lead either to unnecessarily frequent reheating (and thus increased energy consumption), or conversely to insufficient comfort when drawing hot water.

Safety group and cylinder safety

The kit includes a safety group matching the operating pressure of the VIH R 120 cylinder – this safety fitting protects the cylinder against a dangerous rise in pressure when heating water in an enclosed space and is an essential, normatively required part of every pressurised cylinder installation. When the safe pressure value is exceeded, the safety valve automatically opens and releases the overpressure into a prepared drain, which this kit resolves precisely by means of the included siphon.

Function of the siphon in the assembly

The siphon serves to safely and hygienically drain water from the safety valve (if it is activated) and any condensate from the boiler into the sewage system, while its water seal prevents sewage odours from entering the installation space. Since condensing boilers produce acidic condensate during operation, properly resolved and functional drainage of this water is an important prerequisite for trouble-free and hygienic operation of the entire heat source.

Installation

Installation of this connection kit is part of the overall installation of the boiler + cylinder assembly and should be carried out simultaneously with the installation of the boiler and cylinder themselves, exclusively by a qualified installer authorised to install gas and pressurised equipment. Correct connection includes not only the mechanical joining of the piping, but also the correct fitting of the temperature sensor into the corresponding immersion sleeve of the cylinder (with regard to good thermal contact with the sleeve wall, possibly using thermally conductive paste according to the manufacturer's instructions) and the correct routing of the drain via the siphon into the sewage system while maintaining sufficient gradient.

Compatibility

This connection kit is designed specifically for the combination of Vaillant ecoTEC plus wall-mounted boilers with the external VIH R 120 cylinder – that is, specifically for the 120-litre capacity. For other cylinder capacities (for example 150 litres), a corresponding variant of the connection kit must be chosen, since the connection dimensions and the safety group may differ between the various cylinder capacities. Before ordering, we recommend verifying the exact model of the cylinder and boiler with which the kit will be combined.

Why choose the original connection kit instead of an individual solution

Assembling the boiler–cylinder connection from individually procured parts (piping, fittings, sensor, siphon) carries the risk of an incorrect combination of parameters – for example, an inappropriately sized safety group, or an incompatible type of temperature sensor that may not be supported by the control system of the specific boiler. The original Vaillant connection kit eliminates these risks, since all components are designed and tested by the manufacturer as a functional whole specifically for the given combination of boiler and cylinder.

Maintenance

As part of the regular annual service inspection of the boiler and cylinder, we also recommend checking the functionality of the safety valve (using the test lever), the patency of the siphon and drain, as well as the correct fitting and functioning of the temperature sensor. A clogged siphon or a malfunctioning temperature sensor can be a fairly inconspicuous, yet in practice common, cause of reduced hot water preparation comfort, so it is worth paying attention to them even outside of major faults.

Frequently asked questions

Broader context – benefits of a comprehensive, manufacturer-verified connection

The combination of the ecoTEC plus boiler with the VIH R 120 cylinder is among the most frequently implemented configurations for medium-sized households, which is why Vaillant offers a well-thought-out connection kit for this combination instead of leaving the choice of individual components to the installation company. The result is not only faster and simpler installation (shortening the time spent on site, which also reduces labour costs), but above all the assurance that the entire hydraulic circuit between the boiler and the cylinder will function exactly as the manufacturer intended – including correct communication between the temperature sensor and the boiler control.

When ordering this kit, we also recommend considering any additional accessories, such as insulating aesthetic covers for concealed placement of the cylinder under the boiler (if the cylinder is not meant to be freely visible in the space), or additional soundproofing insulation if the installation is carried out near living areas. We will be happy to advise you when choosing the complete assembly, taking into account the layout of your specific space.

Cylinder placement – next to the boiler or underneath the boiler

In practice, the VIH R 120 cylinder is commonly installed either next to the boiler (in a separate location on the wall of the utility room), or directly underneath the boiler, if required by the layout of the space – for example in a small kitchen niche where there is not enough room for two separate appliances side by side. This connection kit is designed to handle both common configurations, although the length and routing of the connecting piping itself may vary slightly depending on the chosen configuration. When installing the cylinder directly under the boiler, we also recommend considering an insulating aesthetic cover, which unifies the visual impression of the entire assembly and also partly helps reduce heat losses from the surface of the cylinder and connecting piping.

Why a well-designed connection is more important than it might seem at first glance

From an ordinary customer's point of view, the hydraulic connection between the boiler and the external cylinder is a barely visible yet functionally key part of the entire heating assembly – it is through this connection that the heat transfer medium flows towards the cylinder's heat exchanger and back to the boiler, and it is here that the sensor is fitted, informing the control system of the cylinder's charge status. Any inaccuracies in this part of the installation (leaks, incorrectly placed sensor, undersized piping) will directly manifest either in reduced hot water comfort or in the overall efficiency of the system, even if the boiler and cylinder themselves were chosen correctly and are of good quality.

Frequently asked questions – additional

Interdependence of the kit's components from a warranty perspective

One of the less obvious, yet in practice important, advantages of the original connection kit is also the question of warranty – if a fault occurred during individual assembly of the connection from various sources due to an incorrect combination of components (for example an incompatible temperature sensor), it could, in an extreme case, be disputable whether the warranty on the boiler itself or on the cylinder would cover such a fault. By using the complete original kit from the manufacturer, you avoid this uncertainty – all components are part of a single, manufacturer-approved solution designed precisely for the given combination of boiler and cylinder.

This assurance is particularly important for larger investments in a quality heating system, where the customer rightly wants to be certain of trouble-free warranty and post-warranty support throughout the entire service life of the equipment.

Summary – why this kit is a good choice for an average household

The combination of the ecoTEC plus boiler with the VIH R 120 cylinder represents a proven and price- and space-balanced solution for the vast majority of apartments and smaller family houses in Slovakia. This connection kit eliminates the most common stumbling block when implementing such an assembly – namely the risk of an incorrect combination of the individual connection components – and allows the installation company to focus on high-quality execution of the installation itself instead of sourcing and verifying the compatibility of individual separate parts. For the end customer, this ultimately means a faster, more reliable and less risky implementation of the entire project of replacing or newly installing the heat source.

When ordering, we also recommend thinking about the implementation schedule – since this kit is designed precisely for the combination with the ecoTEC plus boiler and the VIH R 120 cylinder, delivering it together with the order for the boiler and cylinder themselves allows the installation company to schedule the entire installation on a single working date without waiting for additional parts, which shortens the overall time needed to replace the heat source in your household.

Last but not least, when ordering we recommend stating whether it is a new installation in a new building, or a replacement of an older assembly in an existing building – when replacing an older installation, it may also be necessary to adjust the routing of the original piping or add missing elements that the older installation may not have included (for example, if the original assembly did not have a separate siphon for condensate drainage). Our technical advisors will be happy to assess your specific case and recommend whether this standard kit will fully cover your situation, or whether it is advisable to add further components.