Vitocrossal 300 CT3U - ideal as an attic heating centre

Take advantage of these benefits

  • Low weight, therefore suitable for attic heating centres
  • Low operating costs result from high utilisation of the condensing effect due to optimised hydraulic connections
  • Smooth stainless steel heat exchanger surfaces create self-cleaning effect
  • Hydraulically separated connection of high and low temperature heating circuits
  • Access to burner and heat exchanger from the front for maintenance

Light and compact

The Vitocrossal 300 C3TU is a floorstanding gas condensing boiler with Inox-Crossal heat exchanger and MatriX cylinder burner.

With an output of 400 to 630 kW, this compact gas condensing boiler is suitable for heating apartment buildings and public or commercial premises.

Its compact dimensions and low weight are a particular advantage. The boiler is delivered in two sections, allowing easy installation in attic heating centres.

Highly effective heat transfer

Its vertically arranged heat exchanger surfaces exploit the condensation energy in its hot gases particularly well, with up to 98 percent of the energy used being converted into heat.

Two separate return connectors for linking one high and one low temperature heating circuit let the Vitocrossal 300 utilise the condensing effect with particular vigour.

The smooth stainless steel heat exchanger surface creates a continuous self-cleaning effect. The condensate can flow freely downwards, keeping the surface clean. This extends the service life and reduces maintenance effort.

Comfortable and powerful Vitotronic control with colour touchscreen display

Comfortable and powerful Vitotronic control

The Vitotronic control system with a large colour touch display allows fast commissioning by means of an assistance function as well as simple operation. Via the integrated LAN interface, the boiler can be directly connected to the Internet for remote monitoring. The Vitosoft 300 service tool communicates directly via WLAN. Energy consumption can be easily viewed via the control energy cockpit.

Product cross-section


Output (kW)
400 to 630 kW
Standard seasonal efficiency [to DIN]
98 % (Hs) [gross cv] / 109 % (Hi) [net cv]
Energy efficiency class
Natural Gas & LPG
Application range
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Large residential buildings, commerce, municipal offices, new build and modernisation projects
Easy-to-use Vitotronic control unit
DHW heating
Additional DHW cylinder(s) required, resulting in a high level of DHW convenience
Additional features
MatriX cylinder burner
Produktschnitt Gas-Brennwertkessel Vitocrossal 300 Typ CT3U


A perfect match – System technology

"The whole is greater than the sum of its parts". Following this philosophy, Viessmann supplies more than high quality, reliable and effective heating components. In fact, all products are part of a matching total concept, where all components complement one another. After all, only perfect interaction between all system components can draw out the maximum potential of our innovative leading technology.

Viessmann system technology incorporates everything you need for a reliable and economical heating system: From the Vitotronic control unit with wireless remote control, powerful Vitocell DHW cylinders for the highest DHW convenience, right up to high grade solar thermal systems for cost effective central heating backup.