Tel: 0121 585 5211

HVAC Systems Review


Early man would build a fire in the centre of his combustible hut or damp cave. Even when coal came into regular use the efficiency of each open fire place meant that most of the heating went up the chimney, (it would have been warmer to sit on the roof), with added danger of chimney fires or sparks causing the home, especially dwellings with a thatched roof, to burn to the ground. We obviously had to think of something better, stand up Polish-born Russian, businessman, Franz San Galli, he invented the heating radiator in St Petersburg between 1855-1857.  

His invention was taken up by the wealthy Victorians as the ‘must have’ of the day, although the Radiator sensation in Great Britain really took off during the early 20th century. Although there are earlier beginnings of radiator development in the 1830’s the concept we see today is mostly based on designs by the inventive Americans, Joseph Nason and Robert Briggs in around 1863 with later design additions of the cast iron ‘Bundy Loop’ by another American, Nelson H Bundy in 1872. All the radiators of the day were run by steam, rather than hot water today. 


Boilers are systems designed for heating air or water to produce heat or energy. They can be incredibly simple or fairly elaborate, but basic models are made up of an enclosed container where heat is applied to water, which is then circulated throughout the system in the form of hot water or steam. The water must be boiled to create steam, giving the device its name. 

Many home heating systems and water heaters that use boilers don’t actually boil the water, however. Instead, water is generally heated to temperatures somewhere roughly between 42.14° to 93.3°C, although some people lower the settings to save energy and money. 

Much like a typical furnace heats air, boilers heat water or other heating fluids. The heated liquid then passes through pipes rather than ductwork to a particular heating implement, such as a radiator, to disburse heat. With radiant heating systems, sometimes referred to as heated floors, pipes can be placed in the floor or ceiling. The water is heated, and then moved through the pipes, which distribute heat throughout the space instead of at the end of a line via some other form of heating implement. 

Typical Central Heating Layout (Courtesy of Worcester Boilers) 

Condensing Boilers 

The process by which a condensing boiler works is actually quite simple: Water vapor in the form of steam is produced by normal boilers due to the combustion of hydrogen in the fuel being used. This vapor turns to steam and is quickly released out a chimney pipe. You would not want that steam to stick around your conventional boiler since it is highly acidic and very corrosive to the boiler. 

Engineers who develop HVAC technology realized that it was too bad that all of this steam was escaping since in their minds heat equals energy. There was a realization that if a system could be designed that used this heat energy and was resistant to its harmful effects, a win-win would be attained. This is how the idea of condensing boilers came about. 

As of 2015, condensing boiler sales are rising at a fast pace. Property owners are looking for simple and easy alternatives to conventional heating, cooling, and power systems and while the use of full renewable energy systems such as solar and wind power are not yet mainstream, super high-efficiency systems that can be easily installed and run on conventional fuel are becoming more popular. You’ve come to the right place to learn more about these green alternative energy systems! Thank you for visiting and learning more about high-efficiency condensing and combi boilers! The next time someone asks “What is a condensing boiler?”, you will know the answer! Also, the next time you look at your furnace chimney, realize that your current conventional boiler is losing valuable heat and energy each time it is used, and imagine a system that, instead of allowing this heated air to escape, would put it to good use. 

Condensing boilers are based on a remarkably simple concept, and are an elegant yet powerful solution for those who want to get more energy efficiency out of their home energy system. They are an alternative energy system for today’s home that is available right now and relatively easy and inexpensive to buy, install and maintain. 

Types of Condensing Boiler 

There are basically three different types of super high-efficiency condensing boilers available to a homeowner in the US, UK and Europe. The choice between them will depend on the space you have available, the design of your current system, and your desire for efficiency. The three types of condensing boiler are:

  • Standard condensing boilers
  • System condensing boilers
  • Combi-boilers

About 100 BC a Roman engineer called Sergius Orata designed a system of central heating, known as the hypocaust. 

Standard Condensing Boilers

These are also sometimes called a “heat only” type sends hot water directly to where it is needed. This type of condensing boiler looks conventional, sending water to a storage tank to hold hot water until it is needed for your shower or sink. Regular condensing boilers also need a feed tank of water. Regular models take up the most floor space. 

System Condensing Boilers

These models have the hot water going more directly from the boiler itself, rather than from the tank, and they also do not need a feed tank. Of course the greatest benefit of these models is that they take up little space. 


These boiler systems do not require a hot water tank at all, and merely heat up water flowing through as it is needed. Of course the combi-boiler takes up the least floor space and is therefore the most popular type of condensing boiler. 

Your choice in condensing boiler will depend on how much you want to pay in conversion, how quickly you need to recoup your investment, and the floor space available. It may also depend somewhat on the experience and expertise of the installer you choose. No matter what, however, a super high-efficiency condensing boiler will save you money and energy. 

As with many new and innovative technologies, condensing boilers at the start were not as reliable as conventional boiler systems. This was normal and expected, because sometimes new technologies reach Condensing Boiler Type: Combi Boiler the consumer market before they have been completely tested for longer-term reliability. Also as expected companies were able to fix the problems with reliability quickly as reports cam in from those who were the first to install these renewable energy systems in their homes. Unfortunately, as is often the case, the reputation for poor reliability stuck in some circles. However, now that they have been used substantially in many parts of the world, the bugs are out and they have proven to be highly reliable. 

So, put simply, a condensing boiler is an innovative furnace or boiler that is able to recoup energy that conventional furnaces and boilers lose. Most boilers allow the heat that it produced in the process of burning gas or oil to escape, treating it like a byproduct. Condensing boilers, on the other hand, capture this excess heat energy that is in the form of water vapor. 

Condensing Boilers have taken many parts of Europe by storm, replacing “conventional” boilers and furnaces. In the US people are now beginning to realize the potential of condensing boilers as a home alternative energy source – nor a renewable energy source because they do burn oil or gas, but an alternative that saves money and reduces the home’s carbon footprint. 

Condensing Boilers are costly and may require and initial investment of 40-50% more than a conventional boiler when installation costs are factored in. With the typical savings you will gain from a Condensing Boiler you will start to recover that cost – and begin truly a lot of saving money – in about 2-4 years.  

Split Air Conditioning System 

Split systems provide a convenient way to cool small buildings or specific areas within a building. Typical applications include shops, garages, restaurants and office areas.  

They are sold as a package making them quick to install with minimal disruption to building occupants. Another key benefit of split systems is that they do not require any form of centralised plant space within the building. 

As the name suggests, split cooling systems are made up of two basic 

components: one or more indoor room cooling units, and an outdoor 

refrigeration unit which dumps heat taken from the building. The indoor and outdoor units are linked by pipes which transport refrigerant between the units.  

The cooling capacity of split systems ranges from approximately 2 kW to 

30 kW. The higher capacity systems can incorporate several indoor units, 

or a concealed fan-coil unit can be installed which has one or more 

ducted outlets. 

Some split systems can operate as a heat pump, whereby they are able to 

provide heating by reversing the refrigeration process. The benefit of this 

is that a building’s heating and cooling needs can be provided by one 


Split System’s in an EPC 

Split Systems are ideal and dramatically improve an EPC Grade especially in smaller property’s like shops and offices. 

Due to the capability to cool and heat an area (Inverter) they can control the temperature a lot more than traditional heating.  

A single unit can roughly heat 80m2 of space as a rule of thumb. They are a lot more efficient than other technologies as they use a heat pump essentially turning the cooling mode into reverse and newer heat pumps are around 400% efficient. This means that for every unit of energy used by the heat pump in operation, four or more units of heat are generated for use in a building. 

As heat pumps work by extracting available heat from the outside air, they are far more efficient than even the most efficient fossil-fuel based heating systems. Heat pumps are particularly efficient for all kinds of indoor heating.  

It should be noted that split systems are required to have a Air Conditioning Inspection if over 12Kw as a rule of thumb this is if its over 3000sq/ft of conditioned floor space 


  • Relatively quick and easy to install.
  • Do not require any plant room/area within a building.
  • Heat pump systems can provide heating and cooling.
  • The indoor unit can be concealed if required-Simple occupant control can be provided, with the option of an infrared remote control.
  • Some concealed indoor fan coil-type units can be configured to provide fresh air in addition to re-circulating the room air.   


  • Only suitable for relatively small spaces.
  • Typically require a specialist service operative for repairs and maintenance.
  • Can only service a single internal zone; systems with multiple indoor units cannot provide simultaneous heating and cooling in different areas.
  • Simple split systems only re-circulate room air and cannot provide ventilation.
  • Outdoor units can be unsightly and create noise.

Whilst looking for a New Split look for a system that has an EER of at least 4.0 & SEER of 13.0 

Air Forced Convection Heaters 

Warm air unit heaters are typically used in industrial applications and burn oil, propane or natural gas. There are two basic types of heater: 

Unflued units, where the heat and products of combustion pass directly into the space. This type of unit is particularly energy efficient but requires adequate ventilation to dilute and remove the products of combustion. 

Flued units, which incorporate a heat exchanger that enables air drawn from the space to be heated indirectly and the flue gases to be vented outside the building. 

Both types of heater can either be free standing or mounted at high level.

Key points 

Quick and simple installation. 

Good access to free-standing units for servicing. 

Ductwork can be connected with free-standing units to distribute heat more evenly. 

Condensing units are available which have increased energy efficiency. 


Gas burners require regular checks (typically every six months) to ensure correct operation. 

Free-standing units take up floor space. 

Difficult access to high-level units. 

Heat output is convective which can result in warm air building up at high level (stratification). This may necessitate the use of fans to create air movement and circulate heat evenly throughout the space. This problem is more acute with high-level units. 

Convective heating requires a higher air temperature to be achieved in order to maintain the same level of comfort as a radiant system. This causes greater energy consumption compared to a radiant system. 

Unless an external flue is fitted the products of combustion pass into the building, which requires adequate ventilation. 

Noise from the units may be a problem in quiet environments. 


Tom de Saulles (2002). The Illustrated Guide to Mechanical Building Services. England: The Chameleon Press Ltd. 10 – 35. (2016). Condensing Boiler Guide. Available: Last accessed 23rd Jan 2016.