Vaillant eloBLOCK VE 21/14 EU III electric boiler 21 kW

Product detailed description

Vaillant eloBLOCK VE 21/14 EU III is a powerful wall-mounted electric boiler with an output of 21 kW, designed for family houses with higher heat loss up to approx. 200-210 m² or uninsulated buildings. It is one of the most powerful models in the range, suitable also where a reserve for freezing days is expected, with sufficient power reserve for more demanding heating seasons and lower outdoor temperatures, when a classic heat pump loses part of its output and efficiency.

The boiler is designed for installation into a heating circuit with radiators, underfloor heating or their combination, and already includes everything needed for immediate connection - a highly efficient circulation pump, expansion vessel, safety valve, pressure gauge, thermometer as well as a digital control and information system on the front panel. Thanks to this, installation is quick and does not require purchasing any additional components for the primary circuit.

Technical characteristics

The VE 21/14 model belongs to the Vaillant eloBLOCK VE .. /14 EU III range of electric boilers, which is manufactured in power levels from 6 to 28 kW - you choose exactly according to the heat loss of your building, so that you don't pay for output you won't actually use, nor risk undersizing the heat source.

• Nominal heating output - 21 kW, with the possibility of partial load of 1/2 or 1/3 of output depending on current heat demand
• Electrical connection - 400 V / 50 Hz, three-phase connection, fuse protection 40 A
• Dimensions (H × W × D) - 740 × 410 × 310 mm (height × width × depth)
• Weight - approximately 37.9 kg
• Water volume in the boiler - 10 litres in the boiler body
• Expansion vessel - 7 litres, pressure 0.75 bar
• Maximum operating pressure - 3 bar
• Maximum adjustable heating water temperature - 70 °C
• Heating circuit connections - 3/4" for the heating circuit as well as for a possible domestic hot water tank connection
• Protection rating - IP40
• Space heating energy class - D (space heating)
• Number of heating elements - 1 (with partial output switching)
• Integrated accessories - highly efficient circulation pump, expansion vessel, safety valve, pressure gauge, thermometer, flow temperature sensor, pressure sensor

The control electronics of the VE 21/14 boiler continuously evaluate the flow temperature and system pressure, and switch between individual output levels of the heating element according to current demand - thanks to this, the boiler does not needlessly run at full power if half or a third of the output is sufficient, which saves electricity even during long-term operation. The boiler is intended exclusively for a closed heating circuit (not for instantaneous heating of drinking water) - however, in combination with an indirectly heated domestic hot water tank, it can fully provide domestic hot water heating for the household.

Installation and electrical connection

The VE 21/14 model is connected to a three-phase 400 V/50 Hz supply, and the supply line must be protected by a 40 A circuit breaker - the exact dimension of the supply cable and the type of breaker (characteristic B or C depending on the distribution network) must be designed and implemented by a qualified electrician with a valid inspection report, since this is an appliance with high current draw. We recommend consulting the dimensioning of the house's main protective element (main breaker before the electricity meter) with the electricity distributor in advance, especially if you plan to combine the boiler with other large appliances (heat pump, stove, electric vehicle charger).

When installing, it is also worth considering these points:

• Using a low-tariff night rate (dual-tariff metering) - if the house has a dual-tariff meter with a relay installed, the boiler can use cheaper night-time electricity to heat up the thermal mass of the building or a domestic hot water tank.
• Placing the boiler as close as possible to the heating circuit distribution to minimise heat losses in the piping and the length of the electrical supply.
• Ensuring sufficient space around the boiler for service access and ventilation of the boiler room.
• Adding a room thermostat or Vaillant weather-compensated control (e.g. sensoCOMFORT VRC 720 or VRT 350f) for more precise and economical temperature control in individual rooms.

Use, compatibility and control

The VE 21/14 electric boiler is fully compatible with common heating systems - radiators (panel or ladder type), underfloor heating, or their combination using a mixing station. The boiler can be complemented with an indirectly heated hot water tank (for example the VIH or uniSTOR ranges) to create a complete source of heat and hot water for the household. Control can be extended with room thermostats, weekly programmers, or modern weather-compensated control with a mobile app output, which evaluates the outdoor temperature and regulates the heating water temperature accordingly - this significantly increases comfort as well as operational savings.

If you are not sure whether an output of 21 kW will be sufficient for your building, our range also includes the higher-output eloBLOCK VE 24/14 model. Conversely, for smaller buildings we recommend the eloBLOCK VE 18/14 model, which is sufficient for a smaller heated area at a lower purchase and operating cost.

The boiler is also suitable as:

• Main heat source in the absence of a gas connection or where the burning of solid fuels is prohibited in the given location.
• Supplementary/backup source alongside a heat pump, especially in bivalent connection at very low outdoor temperatures.
• Temporary solution during renovation, until a gas connection or other permanent source is implemented.
• Solution for recreational properties - cottages and cabins, where consumption occurs only occasionally and investing in a gas connection would not be worthwhile.

Maintenance and service

The eloBLOCK VE 21/14 electric boiler is a virtually maintenance-free heat source compared to gas condensing boilers or solid fuel boilers - it contains no burner, flue pipe or chimney that would need regular cleaning. Nevertheless, we recommend:

• Having a service inspection carried out once a year by a qualified technician - checking the tightness of the circuit, the function of the safety valve, the pressure in the expansion vessel and the condition of the heating element.
• Monitoring the heating water pressure on the boiler's pressure gauge and topping up the system according to the instructions in the operating manual if it falls below the recommended value.
• In areas with harder water, considering treatment of the fill water (softening/demineralisation), which extends the lifespan of the heating element and reduces the risk of scale deposits.
• Keeping free space around the boiler and not covering the ventilation openings of the casing.

Thanks to their simple construction and the absence of a combustion process, the lifespan of electric boilers in the eloBLOCK range is generally high and the failure rate low, which, combined with a 2-year warranty from the supplier WINTNER s.r.o., represents a safe and long-term investment.

Why choose the eloBLOCK VE 21/14

Vaillant is one of the most trusted heating technology brands in Europe, and the eloBLOCK range brings the same manufacturing quality to the electric boiler segment as you know from the ecoTEC gas condensing boilers. The VE 21/14 model with an output of 21 kW is one of the most powerful models in the range, suitable also where a reserve for freezing days is expected, making it a well-thought-out choice for family houses with higher heat loss up to approx. 200-210 m² or uninsulated buildings. The boiler arrives fully ready for connection, including the pump and all necessary accessories, so the electrician on site only needs to handle the connection to the electrical grid and the existing heating circuit.

When choosing the right output, it is worth basing the decision on an actual calculation of the building's heat loss (or a designer's recommendation), not just on an approximate floor area - the quality of insulation, ceiling height, number and size of windows, as well as location, all have a significant impact on the required output. If you have any doubts, we are happy to help you choose the right model from the entire eloBLOCK range and design a suitable control system.

Comparison of the entire eloBLOCK VE .. /14 EU III range

The VE 21/14 model, which you are currently viewing, is highlighted in the table below along with the rest of the eloBLOCK range. The table serves for quick orientation if you are not entirely sure whether the selected output is right for your building - all models have the same body dimensions and the same basic equipment (circulation pump, expansion vessel, safety valve), differing in the output of the heating element, weight and required fuse protection.

Approximate operating costs

The exact operating consumption of an electric boiler is always determined mainly by the heat loss of the specific building, the quality of insulation, the set room temperature and the length of the heating season - the following calculation is therefore only indicative and serves as a rough guide. With a model assumption of approximately 1700 hours of equivalent full-output operation during the heating season (typical for family houses with higher heat loss up to approx. 200-210 m² or uninsulated buildings), the annual consumption of the VE 21/14 model would reach approximately 35,700 kWh, which at current electricity prices ranging from approx. 0.18 - 0.28 €/kWh (depending on tariff and supplier) represents approximate annual costs of around €6,426 - €9,996.

Actual consumption can be significantly reduced by using dual-tariff metering with a low-tariff night rate (shifting consumption to the cheaper night-time period), quality insulation of the building, weather-compensated control based on outdoor temperature, and sensible reduction of temperature during absence or at night. We recommend consulting a heating designer or energy auditor for an accurate estimate of operating costs for your specific building.

Frequently asked questions