Glossary of heating and plumbing terms

Confused by the jargon? Keep it simple with our glossary of common heating and plumbing terminology:

Combi boiler

Combi Boiler

A combination boiler, commonly referred to as a ‘combi boiler’, provides two main functions.

Firstly it helps to provide a high level of efficient hot water on demand. It does this by heating your mains cold water supply as it flows through the boiler, helping to give you a continuous supply of hot water. This water is then sent around the property for use at hot water outlets such as taps, showers and baths.

Secondly, the combi boiler provides a property with the hot water needed for your home’s central heating, helping to provide warmth by heating up the radiators within your home.
Both hot water heating and central heating elements are combined within the one unit, helping to give this boiler its name.



In most cases, your new heating system will require at least a few new controls. These include: programmers, room thermostats, hot water cylinder thermostats, 2-port and 3-port valves. Motorised valves divert heat between your radiators and your hot water allowing individual control of both, for example, in the Summer you are unlikely to want your radiators on, but will still require your boiler to heat your hot water.

The specification which your home requires depends very much on the size and design of your property, together with the expectations you have regarding the characteristics of your new heating system. The controls which our Sales Consultant has chosen for you, are specifically designed to give you total control of your system.



Along with heat, when gas or oil is burned within your boiler condensation is also created. This can be seen in the gases which plume out from the boiler, something that is especially noticeable in cold weather. However in addition to this condensate being discharged in the air, condensate also collects inside the boiler and is drained away either inside or outside your home. This is safe and nothing to worry about. 



The Energy-related Products directive (commonly known as ErP) refers to the new legislation that came into force from the 26th September 2015 concerning the way products are labelled with efficiency information.

All water heaters, boilers and other heating products up to 70kW produced from this date for use in domestic and light commercial premises must now be supplied with an ErP label that clearly displays all the relevant efficiency information.

This new efficiency criteria has been brought in across the European Union in order to make end users more aware of the efficiency levels of the products and appliances they are using on a day to day basis. The labels will state minimum performance specifications that relate to efficiency and emissions limits for each appliance.

As a result, all boilers produced by manufacturers after 26 September 2015 will come with an ErP label and will have been built to align with the new ErP requirements in mind.



The flue is the part of the boiler which allows exhaust gases to exit the boiler. The flue is typically situated directly behind the boiler enabling waste gases to exit safely straight out of the external wall of your home.


Fully Pumped

If your system is gravity fed, we will need to convert it to a ‘Fully Pumped’ system. This is a requirement of new high efficiency boilers. The advantage of this is that your new system will run far more efficiently, and this means your boiler will be on for a shorter period, thus reducing your gas consumption.


Fused Spurs

A Fused Spur is an electric point with its own removable fuse and an isolation switch. Current regulations require your new boiler to have an electricity supply from a fused spur, as this ensures that when an engineer carry’s out routine maintenance on your boiler, there is no danger of electrocution. The engineer is able to turn off the switch and remove the fuse, and carry out the service without the danger of someone accidentally switching on the appliance.

If your existing boiler does not have a fused spur, then we will need to fit a new one close to the new boiler position. This will be carried out by a fully qualified and approved electrician, which if it’s required we have arranged and included in your quotation.


Gas Safe Register

It is imperative that anyone who installs or maintains the gas appliances in your home is a qualified Gas Safe heating engineer. This ensures that they are fully compliant with the latest rules and regulations concerning gas installations and repairs and hold the necessary qualifications needs to undertake gas work in a safe and effective manner.

All qualified gas safe engineers are fully compliant with the latest regulations. As the largest independent heating company in the South East of England, all of Swale Heating’s engineers are fully compliant with. Our company Gas Safe registration number is 6494 – for more information please visit the Gas Safe website.

Hot Water Cylinder

A hot water cylinder allows you to store hot water within your property, so that you have a supply ready to use when you need it at hot water outlets in your kitchen and bathrooms (e.g. taps and baths). If you do have a hot water cylinder it will likely be found in your airing cupboard, loft space or another discrete location within your home.

Your requirement for a hot water cylinder will be governed by the type of boiler and heating system setup you have. For example, a combi boiler provides both central heating and hot water on demand so does not need a hot water cylinder, whereas regular and system boilers only directly address the central heating aspect so will require a hot water cylinder to enable you to enjoy hot water at the hot water outlets in your kitchen & bathrooms.



Most common domestic boilers rely on a natural gas fuel supply however some homes who are unable to access the main natural gas grid may rely on a Liquid Petroleum Gas fuel source, more commonly known as LPG, to fuel their boiler.

Typical examples include mobile homes, caravans or out buildings.





Magnaclean (System Filter) & Magnacleanse

Over time heating systems become dirty.  We need to get your system clean to ensure your new boiler works well and will recommend two products, a Magnaclean system filter and a system clean known as a Magnacleanse.  A Magnalcean filter provides effective magnetic and non-magnetic filtration and is simple to install and service.  It provides immediate results and system protection and can cut heating energy bills by up to 6% per year.  A magnacleanse provides fast and effective central heating system flushing with ongoing protection.  It removes virtually ALL suspended black iron oxide, whilst the cleanser remains heated and concentrated throughout the process, which ensures its effectiveness.  The process saves water as there is only disposal at the end.  The addition of a Magnaclean domestic filter provides effective, ongoing protection for the boiler for improved performance and efficiency. Learn more about Magnaclean and Magnacleanse


ME Bonding

ME Bonding is the electrical earth wiring in your property. This is an essential safety requirement in every home. It ensures that all metal parts of your new boiler, copper pipework and your existing bath and / or shower are all ‘earthed’ to the ground. This prevents any of the metal parts of your new heating system becoming electrically charged and prevents electric shocks.

It is very common to find homes where the earthing requires upgrading, but our Sales Consultants are aware of what to look for, and if they feel your earthing is not up to standard, they will recommend that one of our team of electricans inspect your property and advise you of any work which is required. In most cases the work will need to be carried out by your electricity supplier and is free of charge on health and safety grounds.



Over time your heating system builds up sludge and other sediments, which can drastically reduce the efficiency and performance of your boiler. A Powerflush thoroughly cleans your heating system, ensuring that your new boiler works as effectively as possible. 

Our engineers will add a chemical cleaner to your system, and then connect a portable pump, which produces a high pressure flow of water. Each of your radiators will then be turned on and off, and the pressure is directed all over the system, ensuring that your sytem is cleaned as thoroughly as possible. A Powerflush will ensure your new boiler works as efficiently as possible, helping to reduce your gas bills. 

Many of the boiler manufacturers who we use also recommend Powerflushing, and it has been proven to increase the life expectancy of new boilers.

For more information on powerflushing, please click here.



Programmers allow you to stipulate when your central heating comes on. A programmer differs from a more basic timer as it offers more timing options. Timers tend to only allow you to dictate when the heating comes on over a 24 hour period, whereas a programmer lets you set different timings for different days or time zones. Common programmer options include 24 hour, 7 days or 5/2 day (this is useful as you can set weekend heating rules)

Programmers can work in conjunction with a thermostat to allow you to control the temperature that your heating operates at when it is on. If you want this added control it could well be worth looking at a programmable room thermostat as this would let you set your heating timings and temperature settings from 1 device.


Regular Boiler

A Regular boiler or a conventional boiler as some may know it are more commonly found in older properties. Regular and System boilers are an older design of boiler but still offer great functionality and control of your home’s central heating and hot water system. A regular boiler’s two main objectives are to provide central heating and hot water to your home. The way it heats your home is by directly heating the radiators throughout the property to your desired temperature.  The way it provides hot water is by heating a coil, which is fitted into your hot water cylinder in order to heat the stored water.  The hot water cylinder is fed from a cold water storage cistern (or the mains for an unvented cylinder) and a feed and expansion tank supplies the water for the heating system. 


System Boiler

A System boiler operates in a similar fashion to that of a regular boiler. Within its system it still operates using the principle of a stored hot water cylinder, but even though they have this same attribute a System and Regular boiler differ in some crucial aspects. A System boiler directly heats your homes central heating system and also produces hot water, which is stored in your hot water cylinder.  However, a system boiler has many of the major individual components of the heating and hot water system built in, which means that installation is quicker, neater, easier and more efficient.  A system boiler contains the central heating pump and an expansion vessel.  This removes the need for a separate feed and expansion tank and pump being fitted in to the central heating system.  


System Flush

All full installations (new boiler and radiators) we carry out are ‘hot flushed’ upon completion of the work. This ensures that your new system is as clean as possible, which means it will run as efficiently as possible.

Firstly, debris which may have got in to the pipes during the installation is removed by filling the boiler with cold water and adding a cleaning agent, this is then rinsed through the entire system. Secondly, the system is filled again and this time the new boiler is fired and the system is rinsed at high temperature, this ensures that any stray solder or ‘flux’ (the material used to connect pipes) is removed.

Finally the system is filled for the last time, and an ‘inhibitor’ is added to it, this is a chemical which helps to reduce corrosion in the system. This procedure will also be carried out for boiler changes, where we do not Powerflush the system.


A thermostat allows you to stipulate the temperature that your central heating system works to.

It works by switching the central heating system on and off in order to meet your specific temperature requirements. So for example, if you set your thermostat to 20 degrees then the thermostat will monitor the temperature in the air and if it drops to 19 degrees or lower then you’re your central heating will come on. Once the desired temperature is reached (in this case 20 degrees), then your central heating is then switched off.

This allows you to make efficient use of your central heating by only using it when you feel you need it, helping you to save you money and improve your carbon footprint all in one go!

Typically installed in one of the most used rooms in the home, thermostats come in all shapes from a variety of different manufacturers. The level of control that you get varies depending on the device you choose, so there’s plenty out there to meet varying requirements.

Programmable room thermostats are probably the most popular as they allow you to stipulate different temperature settings for different times (the options depend on the device you go for). So for example, you could set your central heating to come on every morning at 8am for 2 hours while you get ready for work and operate at 20 degrees and then get it to turn off throughout the day until 6pm when you come home and want it to operate for 3 hours at 22 degrees. In addition to the digital and mechanical room thermostats available, there are now also a range of internet controlled thermostats available which offer even more flexibility and control – click here for more information.



TRVs are Thermostatic Radiator Valves and these can be fitted in place of your existing radiator valves. Part L Building Regulations published by the Government recommend the use of TRVs as they are an energy saving product. They allow you to set individual heating levels in each of the rooms they are fitted. When the heating system is turned on, the radiator will heat up to the pre-determined level you have set.

The valve will then automatically turn itself on and off to maintain the desired room temperature, until the heating is switched off. TRVs can help to save energy and consequently reduce your gas bill as they stop your heating system wasting unnecessary heat


Waste Collection and Disposal

We will ensure that we remove all redundant materials from your property, including your old boiler. Furthermore, all waste is graded and as much as possible is recycled. All waste which cannot be recycled is disposed of responsibly and safely.

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