New, simplified installation concept for Viessmann Vitocal heat pumps: maximum flexibility in planning and installation
Viessmann Climate Solutions presented a new, simplified installation concept for the Vitocal 250-A and Vitocal 150-A heat pump families at ISH 2025. Four new, modular indoor units are now available. This means that each outdoor unit can be combined with any new indoor unit from the respective series.
Allendorf (Eder), Germany, Dec. 3, 2025 – Viessmann Climate Solutions presented a simplified and highly flexible installation concept for the Vitocal 250-A and Vitocal 150-A heat pump families at ISH 2025. The introduction of new, modular indoor units (IDUs) simplifies system configuration: Each outdoor unit (ODU) is now compatible with every new IDU in the respective series. This separation of outdoor and indoor units enables installers to select the exact indoor unit that meets the individual requirements of the heating system, regardless of the selected output of the outdoor unit – both in new buildings and in modernization projects. Viessmann Climate Solutions is part of the Carrier Global Corporation (NYSE: CARR), global leader in intelligent climate and energy solutions.
High flexibility with new indoor units
With a flow temperature of up to 70 °C, the units have been specially designed for modernization projects. This allows existing radiators to continue to be used without the need for underfloor heating. The four new indoor units in the Vitocal 250 and Vitocal 150 series therefore meet every requirement:
- IDU-A
This wall-mounted indoor unit is particularly suitable for a single heating circuit (1C). Good to know: The version with two heating circuits (2C) will remain in the Viessmann portfolio in its current design. - IDU-A Compact
The floor-standing indoor unit with integrated 190-litre steel storage water heater with Ceraprotect enamel coating is designed for one heating circuit. Here too, the version with two heating circuits in the previous design will remain in the range. - IDU-A Hybrid
This variant is the hybrid version for dual-fuel operation with an existing oil/gas boiler. The IDU-A Hybrid can be combined with the Vitocal 250-A Hybrid up to 18.5 kW or the Vitocal 150-A Hybrid up to 14.9 kW. - IDU-A Modular
The cost-effective option specifically for systems with heating water buffer storage tanks, without expansion vessels. This version is particularly recommended for systems with multiple heating circuits and separate heating water buffer storage tanks, or when using fresh water systems.
Significantly shorter installation and commissioning times
The new indoor units have been designed to optimise the work steps for installers, resulting in significantly shorter installation times:
- Optimized electrical connection space: An optimized, easily accessible electrical connection space with lever terminals in the upper section speeds up wiring.
- Swivelling component box: All electronic components are located in a swivelling box for easy access to the hydraulics and improved serviceability.
- Revised hydraulic interface: A new design eliminates clamp fittings at the hydraulic interface. Connections and valves are directly accessible, which reduces installation time.
- Improved ventilation: The improved ventilation of the indoor unit also contributes to efficiency. A new vent valve on the defrost buffer ensures that air can escape at the highest point, which significantly reduces the ventilation time of the system.
Detailed improvements to the outdoor unit
The outdoor units also benefit from detailed improvements. The noise emissions of the 10 kW and 13 kW models have been reduced from 54 dB(A) to 53 dB(A) in noise-reduced operation. The fan ring heaters (anti-freeze version) are now installed in all outdoor units as standard, eliminating a further installation step on site.
As usual, the heat pumps can be conveniently and safely controlled and commissioned via the Viessmann One Base platform and the ViGuide mobile app.
About Viessmann Climate Solutions
Founded in 1917 as a heating technology manufacturer, today Viessmann Climate Solutions is a leading global provider of sustainable climate (heating, cooling, water and air quality) and renewable energy solutions. The integrated Viessmann Climate Solutions portfolio seamlessly connects products and systems via digital platforms and services, creating an individualized feel-good climate for users. Viessmann Climate Solutions is part of Carrier Global Corporation, global leader in intelligent climate and energy solutions. For more information, visit: www.viessmann-climatesolutions.com
