High‑power condensing boiler VKK 2406/3‑E 0010016464

High‑power condensing boiler designed for large facilities

The VKK 2406/3‑E boiler is a single‑function, floor‑standing gas boiler with a rated output of 247.2 kW at a temperature difference of 50–30 °C. It operates exclusively on natural gas and is intended for central heating in commercial, industrial, or multi‑family buildings where a constant and efficient heat production is required.

Its efficiency reaches 108 % (NRV) and 100 % (GCV), meaning higher performance than conventional boilers – this results from the utilization of exhaust‑gas condensation heat. In practice: more heat per unit of gas, lower bills, and reduced emissions.

Construction and operation – precision for the installer

The internal construction is based on a special heat‑exchanger made of an aluminium‑silicon alloy, which is resistant to the corrosive action of condensate. Exhaust gases are discharged through large‑cross‑section channels that carry heat around the upper combustion chamber – ensuring maximum energy utilisation.

The gas burner, made of non‑scaled stainless steel, operates with full modulation from 49.1 kW to 247.2 kW – there are no power jumps, only smooth adaptation to the building’s demand. A fan with variable speed and a vacuum‑type gas/air pressure control system provides stable combustion even with fluctuating ambient temperatures.

The boiler has an integrated condensate tank – no additional condensate drainage is required beyond the standard sewage connection. Note: condensate pH is about 4.0, so for long runs or sensitive sewage systems a condensate neutraliser should be considered.

Compatibility and installation – what to know before fitting

Technical specifications do not allow “install it anywhere”. Installation components must match:

• Dimensions: 695 mm (width) × 1285 mm (height) × 1550 mm (depth) – sufficient space for service and ventilation is required.

• Working pressure: up to 6 bar – suitable for most hydraulic systems.

• Connections:

- Water inlet/outlet: R2 (return and supply)

- Gas inlet: R1½

- Flue gas channel: Ø200 mm

- Air intake channel: Ø130 mm

• Electrical: 230 V / 50 Hz, maximum power consumption 300 W – no three‑phase supply needed.

The built‑in DIA system displays errors and maintenance information as text, simplifying diagnostics without specialised equipment. eBUS communication enables integration with Vaillant controllers (VRC/VRS), but it is not required for basic operation.

What is advisable to add during installation?

• Hydraulic heat exchanger – if the heating water has unsuitable parameters (e.g., high hardness), an external heat exchanger C240-40 (up to 240 kW) is recommended.

• Safety device – for outputs above 80 kW a safety set with capacity R1 (not R3/4) is required.

• Pump – the standard pump is insufficient for large circuits; high‑capacity pumps such as Wilo Stratos or equivalent are advised.

• Condensate neutraliser – if condensate drainage to the sewage system is problematic (e.g., concrete pipes), install a condensate neutraliser sized for up to 240 kW.

A hydraulic heat exchanger becomes mandatory when the flow of heating water does not meet the manufacturer’s requirements. Insufficient flow can lead to overheating of the heat‑exchanger.

The boiler does not include an internal buffer tank or water heater – it functions solely as a heat source for the heating system. Consequently, its overall efficiency depends on how well it is integrated with the rest of the installation.