uniSTOR plus VIH SW 500

Product detailed description

The hot water storage tank Vaillant uniSTOR plus VIH SW 500 is a glazed stationary hot water storage tank with indirect heating (internal tube heat exchanger), with a volume of 500 liters. It belongs to the uniSTOR plus model range, which Vaillant offers in several construction versions – R (round design), RW (round design with an additional bottom heat exchanger, e.g., for solar heating), S (slim/compact design), and SW (slim design with an additional bottom heat exchanger). The designation "SW" in the code VIH SW 500 therefore refers to the slimmer shape of the tank (compared to the round R/RW series) in combination with an additional bottom heat exchanger, which allows connection of a second heat source (e.g., a solar system) in addition to the primary heating source. This tank is part of the common product family uniSTOR (without solar heating) and auroSTOR (with solar heating), where both series share the same tank construction versions R, RW, S, and SW.

What is the hot water storage tank used for

The tank VIH SW 500 is not a heating source in itself – it is used for accumulating and maintaining hot domestic (sanitary) water, which is heated by a connected heat source (e.g., a gas condensing boiler, heat pump, or solar system) via an internal tube heat exchanger. Thanks to its large volume of 500 liters, it is suitable for households with higher hot water consumption, or for combination with slower-responding heat sources, such as heat pumps, where a large tank compensates for the mismatch between the source's output and the immediate hot water demand.

Technical specifications (verified official Vaillant data for the 500 l capacity platform in the uniSTOR plus series)

• Nominal volume: 500 l (capacity class of tanks 300 – 500 l in the uniSTOR plus series)
• Empty weight (tank without water): 235 kg
• Weight ready for operation (filled with water): 694 kg
• Dimensions (H × W × D): approximately 1 802 × 790 × 900 mm
• Heat exchanger area (heating coil): 5.90 m²
• Inner tank: steel with glazed surface, with a magnesium protective anode against corrosion
• Maximum operating pressure (hot water): 1 MPa (10 bar)
• Maximum allowable temperature of hot water: 85 °C
• Maximum temperature of heating water at the outlet (primary circuit): 110 °C
• Energy efficiency class (ErP): according to the manufacturer's documentation for this capacity class (see the energy label attached to the product)

Note: the values of weight, dimensions, and heat exchanger area are based on the official technical documentation from Vaillant for the 500-liter capacity platform of the uniSTOR plus series (model VIH RW 500/3 BR). A separate publicly published technical sheet for the specific version VIH SW 500 was not available at the time of processing – the construction platform (tank, insulation, heat exchanger) is consistent across the R/RW/S/SW versions within this capacity class, with the main differences being the shape of the casing and the number/arrangement of heat exchangers. Precise parameters should also be verified according to the production label on the specific tank unit.

Construction and equipment

The tank is made of steel with a glazed inner surface, which ensures high resistance to corrosion when in contact with drinking water. As an additional protection against corrosion, a magnesium protective anode is used, which must be regularly inspected (recommended inspection interval: annually, starting after the first 2 years of operation). The tank is externally equipped with thermal insulation that reduces heat losses in standby mode. Part of the construction is a submersion sleeve for the tank temperature sensor, which communicates with the connected heat source and enables automatic control of the heating.

Installation and compatibility

The VIH SW 500 tank is intended for installation in a dry, frost-resistant space with sufficient floor load capacity – the 500-liter tank, when filled, weighs almost 700 kg, so the load must be considered when choosing the installation location. The tank is connected on the heating side to a heat source (e.g., Vaillant ecoTEC gas condensing boiler, Vaillant aroTHERM heat pump) via the tank's outlet and return, on the drinking water side to the cold and hot water supply, and optionally to a circulation pipe. A safety valve dimensioned for the maximum operating pressure of the tank must be installed in the cold water pipe. Installation, commissioning, as well as the connection of the temperature sensor and the BMU cable (in combination with modulating heat sources from Vaillant) must be carried out exclusively by a qualified and trained service technician, in accordance with the manufacturer's installation instructions and applicable standards for hot and cold water distribution.

Protection against legionella bacteria proliferation

When operating large-volume hot water storage tanks, it is important to follow the principles of prevention against legionella bacteria proliferation, which multiply at temperatures below 60 °C. It is recommended to regularly (e.g., once a week) set the tank temperature to a value ≥ 60 °C to ensure thermal disinfection of the entire water volume. At the same time, the hardness and conductivity of the incoming water must be considered, and in case of need, measures for water softening and corrosion protection should be taken (e.g., according to the VDI 2035 guideline).

Maintenance

Regular annual maintenance of the tank includes checking the tightness of all connections, functional testing of the safety valve, checking the wear of the magnesium protective anode (replacement when about 60 % of the anode material is eroded), and a visual inspection of the tightness of the inspection/cleaning flange. During maintenance and possible repairs, it is recommended to use only original Vaillant spare parts to ensure product compatibility and trouble-free operation warranty.

Frequently asked questions (FAQ)

What is the difference between the VIH SW and VIH RW tank?
Both models have the same volume of 500 l and a similar internal construction (glazed steel tank with a tube heat exchanger and magnesium anode), they differ mainly in the shape of the casing (round R/RW vs. slim S/SW) and in the presence/arrangement of an additional heat exchanger for an alternative heat source (e.g., a solar system).

Can the tank be combined with the Vaillant aroTHERM heat pump?
Yes, the uniSTOR plus series tanks are designed to be combined with a wide range of heat sources, including Vaillant heat pumps, with which they share compatible temperature sensor connections and control communication.

What is the maximum temperature of hot water in the tank?
The maximum allowable temperature of hot (sanitary) water is 85 °C, the maximum temperature of heating water on the primary circuit side (via the heat exchanger) is 110 °C.

How often should the protective anode be checked?
Annual inspection is recommended after the first two years of tank operation, or earlier in case of highly aggressive water.

Why choose a 500 l large-volume tank

The choice of hot water tank volume depends on the number of people in the household, the number of outlets (bathrooms, kitchen), and the type of heat source. A 500-liter tank is suitable especially for larger households (5 or more people), households with multiple bathrooms, or for combination with a heat pump, where it is advantageous to have a larger supply of already heated water due to the lower immediate output of the source. A large volume also reduces the frequency of reheating and allows better utilization of cheaper electricity (e.g., in the night tariff) or excess energy from photovoltaics when combined with a heat pump.

Safety and standards

The tank is certified in accordance with the relevant European directives (CE marking) and must be installed in accordance with the current Slovak standards for hot and cold water distribution (e.g., STN 06 0320 – Heating of domestic water, STN 06 0830 – Safety devices for central heating and hot water heating). It is mandatory to install a safety valve with the appropriate opening pressure in the cold water pipe before the tank to prevent excessive pressure rise in the tank during water heating.