Vaillant uniSTOR VIH R 300

Product detailed description

Vaillant uniSTOR VIH R 300 – large-capacity stationary domestic hot water cylinder, 300 litres

Vaillant uniSTOR VIH R 300 belongs to the range of large-capacity cylindrical tanks VIH R 300/400/500, which are structurally different from the smaller 120/150/200 l models – instead of a low, wide shape, they have a tall, narrow cylindrical shape with a diameter of only around 660 mm, which means they take up a relatively small footprint in the boiler room despite their large volume. The cylinder is primarily designed for stationary (cast iron and steel) Vaillant VK series boilers, but it can also be connected to other heat sources of suitable output. The domestic hot water is heated indirectly – a large-area heating coil connected to the heating water circuit is located inside the tank, ensuring continuous heating to the required temperature without the cylinder itself requiring any electrical energy.

The 300-litre volume is intended for buildings with higher or occasionally very high hot water consumption – larger family houses with multiple bathrooms, apartment buildings with central hot water preparation, catering establishments, accommodation facilities, medical practices or other commercial and healthcare facilities where it is important to always have a sufficient supply of hot water ready for immediate use.

Technical characteristics

Construction and internal equipment

The inner tank is made of steel sheet with an enamelled (glazed) interior surface that provides long-term resistance to the corrosive effects of water. As additional protection, the cylinder has a built-in magnesium sacrificial anode, which is gradually consumed during operation and thus protects the steel tank wall itself from corrosion – its condition should be checked regularly through the 120 mm diameter inspection opening, which also serves for checking and, if necessary, cleaning the inside of the tank of sediment. Inside is a large-area heating coil with a heat exchange area of 1.6 m², which, at a heating water flow rate of 2.0 m³/h and a pressure loss of 7.5 kPa, achieves a continuous output of up to 1,130 l/h (corresponding to a heat output of approximately 46 kW) – significantly more than the smaller models of the uniSTOR VIH R 120/150/200 range can provide.

An important feature of this range is also the presence of a separate G1½" flanged connection intended for the optional installation of an electric heating element (sold separately, see the offer of 2/4/6 kW electric heating elements or the intelligent photovoltaic version 0.5–3.5 kW) – this option is typical precisely for the 300–500 l volume category and allows the heating boiler to be completely shut down in summer and the hot water to be heated purely electrically, or to make use of surplus energy from a photovoltaic power plant.

Installation

The cylinder is installed as a stationary unit on the floor of the boiler room or utility room, near the heat source. Given the weight of the filled cylinder (300 l of water plus the weight of the tank, i.e. together well over 400 kg), it must be placed on a sufficiently load-bearing and level floor, preferably on a masonry or concrete base. Connection to the heat source is made via R1" ports on the heating water side, cold and hot water pipework is also connected via R1" connections, circulation via R¾". Part of a correct installation is a safety valve corresponding to the operating pressure of 1.0 MPa and its safe discharge, as well as sufficient free space around the inspection opening and any electric heating element for future servicing.

For optimal control of temperature and heating time, it is recommended to add a control system with the option of setting the hot water temperature in the range of 40–70 °C and with weather-compensated boiler control depending on the outdoor temperature – such control increases operating efficiency especially in the summer months, when high output is not needed for space heating, but only for hot water preparation.

Who is this cylinder suitable for

The 300 l volume from the VIH R 300/400/500 range is suitable for:

• larger family houses with multiple bathrooms and high simultaneous consumption,
• apartment buildings with a central boiler room and shared hot water preparation for multiple housing units,
• smaller commercial and accommodation facilities (guesthouses, medical practices, service businesses) with occasional high demand,
• households planning to add photovoltaics and electric hot water top-up from surplus production in the future.

If your consumption is lower, consider rather the smaller models of the uniSTOR VIH R 120/150/200 range, which have a more favourable price-to-size ratio for a typical household of up to 4–5 people. Conversely, for higher demands or planned photovoltaics, we recommend considering a volume of 400 or 500 litres straight away, or combining it with an intelligent electric heating element already at the initial installation, to avoid later additional pipework modifications.

Connection with a boiler cascade and distributors

In larger installations, for example in apartment buildings or facilities with higher output requirements, the uniSTOR VIH R 300 cylinder is often connected to a system with a heating water distributor and possibly also with a cascade of two or more Vaillant boilers. In such a configuration, the cylinder functions as the central point for DHW preparation, while the space heating itself is controlled independently via its own heating circuits. This type of connection is worth consulting with a heating designer, who will design the correct hydraulic separation of the circuits (for example using a hydraulic separator) so that hot water preparation always has priority over heating, which is common and recommended practice when designing such systems.

Compatibility

The cylinder is primarily designed for stationary cast iron Vaillant VK series boilers, but thanks to universal threaded connections (R1" on both the heating and DHW side), it can also be connected to other heat sources of suitable output, including older existing boiler rooms during renovation. Independence from electrical energy (unless the optional electric heating element is added) means that the cylinder works reliably even in the event of a power outage, as long as the heat source is running.

Safety

A necessary part of the installation is a safety valve rated for a max. operating pressure of 1.0 MPa with safe discharge of pressurised water, for example into a floor drain. We recommend setting the hot water temperature on the heat source thermostat to 55–60 °C for hygienic and energy reasons, supplemented by a thermostatic mixing valve at the outlet for a safe temperature at the point of use.

Maintenance

Regular annual maintenance should include checking the condition of the magnesium anode through the inspection opening, checking the tightness of the flange cover and safety valve, possibly desludging the bottom of the tank of sediment from the water supply network (especially in areas with harder water) and checking the casing insulation. With proper maintenance, enamelled Vaillant cylinders achieve a service life of 15 years or more.

Scope of delivery

The delivery includes an enamelled cylindrical tank with a built-in heating coil, magnesium anode, thermal insulation and outer casing, an immersion sleeve for the temperature sensor, an inspection opening with cover, and connection ports with marked thread dimensions. The electric heating element, mounting flange, safety valve, connection sets for a specific boiler and control accessories are supplied separately according to the needs of the specific installation.

Why choose this particular model

uniSTOR VIH R 300 combines a large volume, a compact cylindrical shape with a small footprint, a high continuous output of 46 kW and the option of later adding electric heating – an ideal solution for more demanding buildings that need reliable, large-capacity hot water preparation without compromising on comfort, even with simultaneous consumption at multiple points at once.

Comparison with larger models of the range (400 and 500 l)

Besides the 300-litre version, the Vaillant range of large-capacity cylinders is also manufactured in volumes of 400 and 500 litres, with all three sharing the same design principle and the same type of connections. The 400 l model has a lower but wider construction (height approx. 1,470 mm, tank diameter 650 mm) with a coil heat exchange area identical to the 300-litre model (1.6 m²) and the same continuous output of 46 kW – in practice, this means the same heat exchanger in a larger volume tank, which is advantageous if you need a larger water supply but not necessarily higher instantaneous output. The 500 l model has a more powerful heat exchanger with an area of 2.1 m² and a continuous output of up to 62 kW (1,523 l/h), and is designed for buildings with the highest demands for simultaneous hot water consumption at many points at once. The choice between 300, 400 and 500 litres should be based primarily on the number of users, the number of simultaneously used draw-off points and the space available in the boiler room – the 300-litre model is the most universal and most frequently chosen size in this category.

Combination with electric heating and photovoltaics

One of the main advantages of the VIH R 300/400/500 range over the smaller 120/150/200 l models is precisely the option of adding an optional electric heating element via the G1½" flanged connection. At atria.sk you will find two variants of this accessory – a classic switchable element with an output of 2, 4 or 6 kW intended for simple summer top-up heating without the need to run the boiler, and an intelligent version with energy consumption control in the range of 0.5–3.5 kW, which is specially designed to work together with a home photovoltaic power plant – instead of selling surplus generated electrical energy to the grid at a low purchase price, it converts it directly into heat in the hot water cylinder, thereby increasing the self-consumption rate of the photovoltaic system and shortening the payback period of the investment in solar panels. Both versions of the element are fitted into the same G1½" flange using a separately available mounting flange.

Energy class and efficiency

Cylinders of this range achieve energy class B for static losses (according to the energy efficiency labelling for hot water cylinders) with a quality polyurethane insulation thickness of around 75 mm, which, at a volume of 300 l, represents a very good ratio between capacity and heat losses. In practice, this means that even with intermittent night-time heating or longer periods without draw-off, the operating costs of maintaining the temperature in the cylinder remain at a reasonable level compared to the total energy consumption of a larger household or facility.

Frequently Asked Questions