Types of Central Heating Systems

Types of Central Heating Systems


If you are looking to update or replace the central heating system in your home, here is a comprehensive guide on how to choose the right heating system to suit your home. 

There are lots of factors to take into consideration before deciding on the ideal option to keep your home warm. 

In most cases, homeowners will need something that falls in the middle. If this is the case for you, then there are various options to choose from. Before you proceed further, it would be in your best interests to check on the heating system type that you are currently using. 

The costs involved to fit and supply a boiler typically vary according to the size, brand, and installation cost. The cost to install a boiler will increase significantly should you decide on a system that is completely different from the current system. Depending on the current state of your heating-system this might not or might be a cost-effective option to choose.

It is also worthwhile noting that the prices vary considerably from one installer to the next. For this reason, we suggest that you compare 3 to 4 quotes to ensure you are choosing a system that is competitively priced. 


Electric Vs. Gas Systems

Central heating systems are usually the last thing that most homeowners think about. It is also something that is often taken for granted, with many homeowners assuming that when the winter months start approaching that their radiators and boilers will continue to do a good job. But what system is more reliable? A gas or electric heating system? Which type is more cost-effective to run?

In the next section, we have covered these questions. We hope this will give you the information that you need on whether to go with a gas or electric system.


How Do Gas Heating Systems Work?

In the UK, the gas heating system is the most common. This central heating type also goes by the name of a "wet system" which involves a gas-fired boiler that heats the water. These heating systems provide heating through the radiators and the hot water that comes out of the taps in a home. Here is a step-by-step description of how they work:

Step one: Natural gas supplies the boiler from a pipe that is connected to the gas main out on the street. 

Step Two: The gas jets are aimed at the pipes that contain cold water, heating the pipe up to around 60 degrees Celsius. 

Step Three: Water pipes make up only one section of a larger circuit of continuous pipe. This is a network that travels around your entire home. 

Step Four: The water pipe passes through the hot-water radiators, before returning to the boiler. 

Step Five: As water flows through each radiator, it releases some heat which warms up each of the rooms in your home. The boiler must keep firing to make sure the water remains at a temperature high enough to keep your home warm. 

Step Six: These systems also use electric pumps to direct the flow of water around the pipework circuit and the radiators. 

Step Seven: Houses that are not connected to a gas network still use LPG (liquid petroleum gas) or a type of heating oil that works like gas but is more costly to operate. 

The Running Costs Of Gas

The gas boilers often offer significant savings. Some estimates have suggested a saving of up to £250 per annum in comparison to other fuel types such as LPG, coal, or oil. 

The condensing, high-efficiency gas boilers might convert up to 90% of fuel consumption into useable and useful heat. The condensing gas-boilers are also known for producing a lot less CO2 or carbon dioxide when compared to standard gas boilers. They also lower heat loss from a flue. 


How Do Electric Central Heating Systems Work?

Electric boilers can be used as a replacement for a small or a medium-sized gas boiler, and as technology continues to advance, there are now electric boilers that match up to the requirements of larger homes.

These boilers also require fewer components when compared to gas boilers which makes them lighter, smaller, and more compact. They also run silently and offer an important advantage of being completely efficient. Electric boilers are still regarded as the new-comer to central-heating markets, and they are more commonly found in rural sectors when gas or oil supplies are not readily available. However, today they are also common in flats and newer housing projects that install electric boilers due to their environmental benefits. 

If you are thinking about changing over from a gas boiler to an electric boiler, it is important to know that the costs involved are significant once factoring in the boiler, new piping, and the cost of installation. 


Is It Cheaper To Heat A Home With Electric Or Gas?

Gas-powered central heating systems are usually cheaper over the long term. The electric boilers are regarded as 100% efficient, while the modern gas boilers are around 95% efficient. As is expected, a bit of the energy from a gas boiler will drop through heat. 

Even with a slight shortfall in energy efficiency, the electric boilers at this stage, cannot compete with the 4p / kWh costs of gas. 

If you are not sure about which central heating system to choose for your property, we suggest contacting an engineer. If you provide us with your details we will ask 3 local installers to advise, assess, and send you a quote on a new or replacement boiler. 


The Most Popular Central Heating Systems

Today there are many central heating systems to choose from, which fall into different categories, these include:


1 Combi-Boiler System 

Combination boiler central heating systems are perhaps the most popular system today. This system does not need a hot-water cylinder, expansion tank, or feed tank since they heat water on demand. This also means these systems are more economical and require less space since they are only heating water when you need it. 

The combi-boiler system provides on-demand heated water, which means you won't have to worry about a tank taking up space in your loft space. 



- Electronic controls pair to the boiler

- The main supply is directly fed to the combination system

- The thermostatically-controlled modern radiators are sized accordingly

- Space-saving

- Performs very well in a shower

- Hot water as you need it (on-demand)

- Economical since you are only heating the water that you use

- Eliminates the risk of frozen pipework

- Installation is typically cheaper


Similar to other systems, the combi-boiler system also comes with a few drawbacks. The main concern is the flow rate is relatively low since the water must heat up while traveling through your boiler (there isn't any stored hot water to rely on).

This also means that this system is not suitable for houses with 2 or more bathrooms since using water in 2 bathrooms at the same time will translate into an even slower flow rate.

Combination boilers have 2 heat outputs:

- Hot water for showers and taps

- Hot water for radiators and the central heating system

It requires more heat and effort to provide hot water into a shower or tap than it will to a radiator. For this reason, it is important to consider what type of hot-water output your home will need. 


2 Mains Pressure Heating Systems

This is a system that supplies mains-pressure heated water through taps in a home. 

The water is extracted from the cold-water mains and is then heated by the boiler. 

The water is stored inside the storage tank also known as the "unvented cylinder" until it is needed. 

When you open one of the taps in your home, cold water that comes from the mains forces hot water into your central heating system which then flows out of the tap. 

The pressure at the taps in a high-pressure heating system will be the same pressure of your mains which is usually much higher than what you normally experience. 

This type of central heating system is ideal if you already have a high-mains pressure, but if you have a low mains pressure this is not a suitable system. They are also expensive to install with some authorities requiring a certificate for annual maintenance that you will have to submit to them. 

It is also important to make sure your flow rate and mains pressure will be strong enough so that they can power the central mains-driven heating system. 

If you have gone through the hassle and expense of installing this heating system and the water is only trickling out of your shower or tap, at this stage, there is not much that can be done to rectify the problem. 


Conventional / Regular Boilers

These types of central-heating systems use a system or regular boiler to heat your hot water and the radiators. The heated water will circulate around this system before it is stored inside the hot-water cylinder until you need it. 

Water that goes inside the boiler before it is heated usually comes from either an expansion tank or feed tank located in your loft space. It will also make sure that the water volume inside the system is constantly kept at an optimum level. 

There is also usually, a bigger tank that will replenish the hot-water cylinder after using water around your home. 

Water from the tank draws into this system by gravity, which is where this heating system derived its name from. The main disadvantage to these systems is that they require loft space to accommodate the 2 tanks, along with an airing-cupboard or something similar to accommodate the hot-water cylinder. 

The gravity-based heating system works well if you have low mains-pressure in your area, since the force of gravity associated with these systems usually provides more water pressure, especially when your main pressure is not doing the job. 


Wall-Mounted Boilers

Many of the latest models of boilers are designed to be wall-mounted along with lighter and compact heat exchangers made from materials such as aluminum, copper, stainless steel, or cast iron. 

Wall-mounted boilers are available in various versions which include Room Sealed or Fanned Flue. Similar to many other models of new boilers, these wall-mounted types must have a "system-by-pass" fitted to filter the water through the boiler to stop loud noises that boilers make known as "kettling". 


Free-Standing Boilers

Usually made narrow enough so that they fit between kitchen units. Since they are free-standing you can also install them in another suitable location. These boilers were once popular in the 70s and the 80s, and they are still a good option if you do not have enough wall space available for one of the wall-mounted boilers. 


Condensing Boilers

This boiler type offers a highly effective "heat exchanger" that allows the heat to re-circulate instead of losing this heat in the flue, which makes it a lot more energy-efficient. This can help to reduce your fuel costs significantly. 

One issue that is often mentioned about condensing boilers is the "pluming effect" that they create inside the flue-terminal (it is often mistaken for steam). Plumbing is caused by water droplets that are suspended throughout the flue of the boiler. It is not dangerous in any way but can be regarded as a nuisance that occurs consistently while the boiler runs. Due to this problem, the position or placement of your condensing boiler could be problematic.


About the Author


Heat Quick Direct are Vaillant accredited engineers

Heat Quick Direct is accredited by all the major gas boiler trade bodies, such as Gas Safe and we are approved G3 unvented hot water storage engineers approved by Worcester as accredited engineers and we are approved advanced Vaillant engineers.