Which boiler do we need?

At Viessmann, we offer a comprehensive range of boilers for all kinds of commercial application. With our extensive range, it can be a challenge to choose the right boiler for the needs of your business. To assist you in selecting the boiler system which fulfils your needs, we have compiled this handy guide.

Questions to consider:

How big are your premises?

The size of your commercial premises will be one of the most important considerations when it comes to selecting the ideal boiler. There is little point in choosing a high output boiler designed for large scale industrial application, if you only operate a small commercial unit with a few radiators.

How much space do you have available?

Space is another important consideration. If you looking to heat commercial premises with limited floor space, you should consider whether you have the room for a boiler with a separate hot water tank, or whether a combination boiler will suffice.

Will you need planning permission for a flue or chimney?

If the answer to this question is yes, it may be that a biomass boiler will not be a viable option.

Will it be easy to find an oil or wood pellet supplier for your business?

If you intend to opt for an oil or biomass boiler, rather than a gas boiler which utilises the gas supply connected to your property, you will need to consider how you will obtain the fuels your heating system will be dependent on. Is there a local oil or biomass supplier operating in the local area who could supply your premises?

Fuel type

At Viessmann, we offer commercial boilers utilising three different fuel options. These are gas, oil and biomass. All of our heating systems are also compatible with Viessmann solar thermal technology, this allows your business to benefit from the free energy provided by the sun and utilise this as a backup for your heating and hot water demands. This will enable you to benefit from lower energy consumption and will help to reduce your business overheads.

When it comes to selecting the right fuel type for your specific commercial application, there are a number of considerations to be made.

Gas boilers

The entire gas commercial boiler range from Viessmann consists of gas condensing boilers. By choosing a gas condensing boiler from Viessmann, you will be making an active contribution to the environment due to the unbeaten high efficiency of 98 percent found across our range.

All of our gas condensing boilers can be used in conjunction with Viessmann solar technology. Utilising Viessmann system technology, our gas boilers work in harmony with the other systems available and make effective use of renewable energy options.

Oil boilers

Oil boilers have long been the most popular alternative choice for commercial premises which are not connected to the UK’s gas network.

Our range of oil condensing boilers work in the same way as gas boilers, with the only notable difference being the use of oil as a fuel source to heat the inner pipes and water within your property, as opposed to using gas.

By choosing a Viessmann oil condensing boiler for your commercial application, you will be contributing towards using resources efficiently and saving energy. This is achieved through the use of Viessmann technology, which allows our oil condensing boilers to feature an unbeatable high efficiency of 98 percent (relative to the gross calorific value (Hs)). All of our commercial oil boilers also come equipped with the future and are designed to also be used with fuel oil mixed with a certain percentage of bio-oil, which means that they can be run partially on renewables.


  • The price of oil has continuously been falling over the past few years
  • A highly efficient fuel, meaning that you get a good return on every unit of energy
  • Viessmann oil condensing boilers utilise the hot flue gases which would have otherwise wasted in a standard boiler, enabling them to achieve high efficiencies of up to 98 percent
  • Easy to use
  • Quiet operation
  • Suitable for use with Viessmann’s solar thermal systems



  • Oil will have to be delivered to your business by road, so it is important that you carefully monitor your usage and are prepared for when your supplies run low
  • As you will need an oil storage tank, you should ensure you have the space to accommodate this within your premises
  • Viessmann oil condensing boilers are floor standing, so you will need to consider the space this will take up in your premises
  • The hot water flow rate can be lower than a gas combi boiler 

Biomass boilers

Biomass boilers are a more eco-friendly alternative boiler choice. Fuelled by wood pellets, chips or logs in order to generate heat, they are sometimes also known as wood boilers.

Designed for efficiency, the carbon dioxide given off by wood pellet boilers is similar to that absorbed by new plants, meaning they are a sustainable boiler choice.

Utilising a biomass boiler will enable you to significantly cut your carbon emissions and reduce your business overheads.


  • Eco-friendly - powered by sustainable fuel sources, using wood in a biomass boiler will not produce environment harming carbon dioxide emissions as the levels are equivalent to the levels absorbed by new plants
  • The fuel is very cost effective - made from leftover wood material, wood pellets are cheap to produce and to purchase
  • On average, a biomass boiler costs £600 to run each year
  • Biomass materials are easy to store


  • Larger initial outlay - our biomass boilers are more expensive to initially purchase than our gas and oil boilers. However, this is outweighed by the annual fuel savings over the course of the boiler’s service life
  • Biomass boilers require regular maintenance - unlike gas or oil boilers, a biomass boiler will generate ash from the wood which it burns for fuel. This will need to be emptied on a regular basis otherwise you run the risk of the boiler shutting down
  • Our biomass boilers are typically larger than our gas and oil boilers, so you should consider the space you will need to reserve in your premises for the unit
  • Fuel storage - the storing of wood pellets or logs will also require a large amount of storage space, so you should consider the space which will be required to store this fuel 

The types of boiler offered by Viessmann

Conventional boilers

Conventional boilers are boilers which use a storage tank, holding gallons of water, to supply hot water to your premises. Once this supply of stored hot water runs out, you will need to wait for this to be refilled before it can be used again.
If you choose a conventional boiler, you will need to consider the amount of space you will need for the cold water storage tank.

Combination boilers

Viessmann combination boilers, or combi boilers, work by providing hot water directly from the mains without having to be connected to a storage tank.
A combi boiler is an ideal choice for smaller commercial premises, as all of the components are contained within one unit and there is no need for a separate hot water tank.

System boiler

Viessmann system boilers work by directly supplying hot water to the radiators in your home and a hot water storage cylinder. With a system boiler, the majority of the major components of the heating system, such as the pump and expansion vessel, are contained within a single unit. This makes installation simpler and also simplifies servicing.

System boilers are an ideal choice for properties with more than one bathroom or those who require more hot water than a combi boiler can provide.