Jargon Buster

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


Gas Safe RegisterIt 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 listed in the Gas Safe Register, which can be found online please visit the Gas Safe website.


Combi Boiler AdviceA 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 main water supply as it flows through the boiler, helping to give you an almost instantaneous 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.


Regular Vaillant BoilerOften found in older or more traditional properties, a regular boiler provides the heating aspect of your central heating and works alongside a hot water cylinder to give you the hot water you need at the outlets in your home (i.e. shower & taps).

A typical regular boiler system setup incorporates the boiler itself which works with a hot water storage tank (often found in airing cupboards). This is commonly fed by a cold water storage cistern situated in the loft, an expansion cistern and relies on heating controls to control the central heating performance.

Never heard of a regular boiler? Regular boilers can also be referred to as “conventional” or “heat only” boilers.


System Boiler AdviceA system boiler operates in a very similar way to a regular boiler, working alongside a hot water cylinder to store hot water. There are however slight differences.

The system boiler includes a number of key components within the appliance itself (unlike a regular boiler). This means that less space is taken up when the boiler is installed and also makes the install process neater, faster and more efficient.

A system boiler does not need a feed and expansion cistern, as the hot water that is produced by the boiler is pumped from the boiler to the cylinder and radiators. This gives you a faster response and makes the boiler more economical to operate.


Hot Water CylinderA 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.


Central Heating ControlsIn 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.


Heating System ProgrammerProgrammers 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)


Heating System ThermostatA 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.


Heating System TRVTRVs 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


Heating System Fused SpursA 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 this quotation.


Heating System PowerflushOver time your heating system builds up sludge and other sediment, which can drastically reduce the efficiency and performance of the boiler. A Powerflush thoroughly cleans your heating system, ensuring that your new boiler works as effectively as possible.
The engineer should 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 system 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.


Heating System FlushingAll full installations (new boiler and radiators) an engineer will carry out a ‘hot flush’ 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.