CHP systems provide a practical and effective way to reduce carbon usage domestically and commercially. Running from a single fuel (either fossil fuels or renewable fuels) they utilise new technology within boilers. For many, one of the key benefits of implementing these systems is the ease of installation – CHP boilers can be wall standing or floor standing to act as a direct replacement. Research is vital when it comes to choosing the right solution for our business and knowing all boiler options available to you is just one step.

Here at Energimizer, we select high-efficiency and top-end products for our clients, with four main types of boilers available, as standard.

  • Stainless Steel Condensing Boilers.
  • Cast Iron Boilers.
  • 3-Pass Boilers.
  • Tube Boilers.

Stainless Steel Condensing Boilers

One of the most efficient options on the market, stainless steel condensing boilers is also some of the most popular. They are fuelled by either gas or oil and work by condensing water vapour within the exhaust gas. The heat that exists here can then be captured and reused to heat water in the system. In doing so, this type of boiler can easily achieve a 90% efficiency rating.

These boilers are widely manufactured from stainless steel due to their resistance to corrosion from flue gas. With proper maintenance and care, they can be expected to last anywhere between 10-15 years before a replacement may be needed. In residential properties, it is now UK law to install a condensing boiler as a means of considerably reducing carbon emissions in homes.

Condensing boilers tend to be more expensive than non-condensing boilers. But the return on this investment can also be significant in the long run.

Cast Iron Boilers

Cast iron has long been the option of choice for manufacturing boilers and remains a popular one to this day. As a blend of iron, carbon and silicon, these hard-wearing boilers are popular in UK construction. Being exceptionally strong and highly tolerant to sulphurous flue gas exposure, they also offer good corrosive resistance and longevity for demanding environments. However, they are not suitable for use with condensing systems as the acidity of the gases produced has the potential to cause damage. Overall, this dense material allows you to maintain hot water temperatures for longer and, when powered using natural gas, they help to reduce energy costs by utilising a cheaper form of fuel and allowing you to consume less energy.

3-Pass Shell Boilers

3 pass boilers are designed to get the maximum heat from the fuel provided. They do this through the use of 3 horizontal tubes that allow hot combustion fuel gas to travel through. With triple the amount of interior surface area available to extract heat, they are one of the most efficient options on the market. Shell boilers sit these three horizontal tubes within a steel shell, further trapping energy and allowing them to cope with repeated use over a short period of time. Seeing as all of the components within these boilers sits in a single shekel, they are easy to relocate and generally have a simple control system which may benefit busy growing businesses.

Tube Boilers

A tube boiler features a furnace where the chosen fuel is burned. This creates a hot gas which then boils the water that is contained within tubes that are immersed in water. As the walls of the tube become hotter, the water boils and generates steam using considerably less fuel in the process. There are two types of tube boilers – fire and water. Fire tube boilers are cheaper but can only produce heat and pressure for a short period of time. They are easier to install and simple to operate. In contrast, water tube boilers are considered a safer option with fewer components prone to damage and more power production capacity.

How to Choose the Right Commercial Boiler?

All of the boiler types we have mentioned above can be incorporated into your chosen CHP system. But how do you go about identifying the right option for your business? The right boiler unit for your needs will be sized to suit the scale of your commercial business. Its applications need to meet your requirements, whether needed for running a hospitality business or managing a smaller enterprise.

CHP units have long been designed for commercial use and are only just now stepping into domestic use too. Generally, Stirling engine powered micro-CHP boilers are used in residential settings due to their compact nature and reduced noise capacity. In commercial businesses, you have more flexibility with this, allowing you to focus on other benefits when choosing the right boiler for your needs. Consider the following aspects:


Micro-CHP systems can become a significant investment for businesses – albeit one that promises significant returns over the years too. As with any business decision, it pays to take into account the cost of your chosen boiler. Condensing boilers, as one of the most popular and widely used options, continue to decrease in price to meet the growing demand. However, the technology that goes behind them may mean that one to the scale you need to support your business could sit in the region of £10,000+.

And we recommend, alongside considering the initial purchase cost of a boiler, judging the approximate savings you could achieve over a period of time when choosing a unit – specifically when this is combined with a CHP system in place. Significant reductions in carbon emissions, heightened efficiency and re-usage of waste are all beneficial returns on your initial financial investment.

Energy Efficiency

If you’re considering a micro-CHP unit in the first place, you’re likely concerned about energy efficiency and reducing your carbon footprint. This goes hand-in-hand with choosing the right boiler – it pays to choose one that supports your efforts as much as possible. Overall, condensing boilers are considered the most efficient as they make use of modern heat exchangers to draw as much energy from the condensing vapour as possible. This remains true in both commercial and residential settings.

Maintenance Costs

Micro-CHP systems are designed to benefit the environment and your heating budget. However, another consideration to take into account when choosing one is maintenance costs. A regular servicing package will ensure that minor damages are identified early on, reducing the risk of costly repairs in the future. If you’ve chosen a bespoke boiler model, consider whether replacement parts are readily available and what the cost implication of having key components replaced could be.

Energimizer has over 20 years of experience supplying and maintaining renewable, low carbon and sustainable energy-saving systems for our clients. We provide tailored packages with the right boiler, servicing and maintenance packs alongside general support and advice. Choosing the right boiler to accompany your CHP unit is a key consideration and one that we’re here to help you make. If you have any questions or would like to speak to one of our experts, please get in contact here today.