Viessmann is a German heating manufacturer, and every Vitocal heat pump here is a monobloc using natural R290 refrigerant, so the refrigerant stays sealed in the outdoor unit. The Vitocal 150-A and 250-A are built for homes and both reach 70°C, while the Vitocal 250-A PRO is designed for large properties and commercial buildings.
A monobloc heat pump using natural R290 refrigerant, with flow temperatures up to 70°C. Sizes run from 4kW to 16kW. Choose the 151-A version for a floor-standing indoor unit with a built-in 190-litre hot water cylinder.
Monobloc
Viessmann’s premium monobloc, using R290 and reaching 70°C so it can run with existing radiators. It has a noise-reduced mode and was named the winner in a 2023 heat pump test by German consumer group Stiftung Warentest. Check UK availability with your installer.
Monobloc
A 40kW R290 monobloc for large properties, apartment blocks and commercial buildings. It needs a three-phase supply, reaches 70°C and is designed to cascade up to four units on one indoor unit for bigger heat demands.
Commercial
All three models use R290 and reach 70°C. The choice comes down to the size of your property and whether you want Viessmann’s standard or premium domestic model.
| Vitocal 150-A | Vitocal 250-A | Vitocal 250-A PRO | |
|---|---|---|---|
| Type | Monobloc | Monobloc | Commercial monobloc |
| Outputs | 4, 6, 8, 10, 13 and 16kW | 2.6kW to 13.4kW rated range | 39.5kW, up to 158kW with four units in cascade |
| Refrigerant | R290 (natural) | R290 (natural) | R290 (natural) |
| Max flow temperature | 70°C | 70°C | 70°C |
| Noise | 33.5dB(A) at 3 metres (6kW, standard heating mode) | 35dB(A) at 4 metres in noise-reduced mode | 58.2dB(A) sound power |
| Warranty | 2 years standard, extendable up to 10 years through your installer (terms apply) | 2 years standard, extendable when registered by your installer | 2 years standard, extendable when registered by your installer |
| Best for | Most homes, and the 151-A where you want a built-in cylinder | Homes wanting Viessmann’s premium model and quiet running | Large properties, apartment blocks and commercial sites |
Our comparison guides put each model side by side in plain English, so you can see the differences before you speak to an installer.
Viessmann's Vitocal 250-A was named the winner of a 2023 air-to-water heat pump test by German consumer group Stiftung Warentest, with an overall rating of Good (2.1). The whole range uses natural R290 refrigerant and reaches flow temperatures up to 70°C. As with any brand, the quality of the design and installation makes the biggest difference to how well it runs.
A Viessmann heat pump is priced as part of a full installation, so there's no single figure. The Energy Saving Trust puts the typical cost of installing an air source heat pump at around £14,000. The final figure depends on the output you need, your home, any radiator upgrades and whether you choose the 151-A with its built-in cylinder. In England and Wales, the £7,500 Boiler Upgrade Scheme grant comes off the bill.
Viessmann quotes a sound pressure of 33.5dB(A) at three metres for the 6kW Vitocal 150-A outdoor unit in standard heating mode, with the unit against one wall. The Vitocal 250-A has a noise-reduced mode, with Viessmann quoting 35dB(A) at four metres. Where the unit sits makes a real difference, so your installer should plan its position carefully.
Every Viessmann heat pump has a 2-year warranty as standard. Longer cover is available when your installer registers and extends it within 30 days of installation, and Viessmann has offered an extendable 10-year warranty on the Vitocal 150-A and 151-A, subject to terms. Annual servicing is usually needed to keep the cover valid, so check the details with your installer.
Both use the same type of R290 monobloc outdoor unit. The difference is indoors: the 150-A has a wall-mounted indoor unit and works with a separate hot water cylinder, while the 151-A has a floor-standing indoor unit with a 190-litre hot water cylinder built in. The 151-A is useful if you want the cylinder and controls together in one unit.
For most homes, the Vitocal 150-A covers the sizes you're likely to need, from 4kW to 16kW, and the 151-A adds a built-in cylinder. The Vitocal 250-A is Viessmann's premium choice if you want its noise-reduced mode and test-winning efficiency. The 250-A PRO is for large buildings and commercial sites. A heat loss survey decides the size.
You can, as long as the heat pump, the installation and your home meet the scheme rules, which your installer will check. In England and Wales, the Boiler Upgrade Scheme gives £7,500 towards an air source heat pump, or £9,000 if your off-gas-grid home is replacing oil or LPG, thanks to an extra £1,500 available until March 2027. Your installer applies on your behalf. In Scotland, Home Energy Scotland offers grant funding instead.
Viessmann is a German manufacturer, and its Vitocal 250-A PRO is built at the company's plant in Berlin. Viessmann doesn't publish the factory for every model, so if it matters to you, ask your installer to check for the exact heat pump you're quoted. What matters most day to day is that it's sized and fitted properly.
Our recommended installers
These recommended installers in our network fit Viessmann heat pumps. Each one designs the system around your home, from the heat loss survey to the final handover.
Tell us where you live and we’ll point you to our recommended installer for your area, who can survey your home and size the right model for you.
