Central heating is a system that heats a whole building from one central source. In most UK homes, this is a “wet” system, where a boiler heats water that is then pumped around the house to radiators, and often also provides hot water for taps and showers.
How a Boiler System Works
Most homes in the UK use a gas boiler, although some use oil, LPG or electric boilers. The boiler burns fuel to heat water in a heat exchanger. A pump then circulates the hot water through pipes to the radiators, which give off heat into each room, before the cooler water returns to the boiler to be heated again.
Controls
A central heating system is controlled by a programmer or timer, which sets when the heating comes on, and a room thermostat, which turns the heating on and off to keep the house at the temperature you choose. Thermostatic radiator valves let you control the temperature of individual rooms.
Types of Boiler
There are three main types of boiler. A combi boiler heats water on demand, so it does not need a hot water cylinder. A system boiler heats water that is stored in a cylinder, while a regular or heat-only boiler also uses a cylinder and a cold water tank in the loft.
Heat Pumps
Heat pumps are an increasingly popular low-carbon alternative to boilers. Air source and ground source heat pumps use electricity to take heat from the air or ground outside and use it to warm water for radiators or underfloor heating.
Servicing Your System
Central heating systems should be serviced regularly to keep them safe and efficient, and gas work must be done by a Gas Safe registered engineer. For a range of Copper Pipe products, visit https://watkinspowis.co.uk/products/copper-pipe-fittings-and-press-systems/
Related: How to choose the right boiler for your home
Hidden heating and what buyers look for
Radiators are the most familiar part of a wet system, but they take up wall space and limit where furniture can go. Underfloor heating is the best-known alternative. It can be a wet system, with warm water running through pipes under the floor, or a dry one using electric heating mats. Wet underfloor heating runs at lower water temperatures than radiators, which makes it a good partner for a heat pump. Other options hide heating in skirting boards or walls.
All of these are disruptive to fit, so they are best installed when you are already renovating, extending or replacing floors. If a new system is not on the cards, buyers still value one that works well: a reasonably modern boiler with its service history, good controls and thermostatic valves, and radiators that heat evenly. Many buyers now pay attention to running costs and energy ratings too, so an efficient, well-documented heating system can help a home stand out when it comes to selling.
A short history of the gas we burn
Most boilers run on natural gas, which is made up mainly of methane with smaller amounts of ethane, propane and butane. It is colourless and odourless, so suppliers add a chemical called mercaptan to give it the rotten egg smell that makes a leak easier and safer to detect.
People are thought to have noticed natural gas in ancient times, possibly when lightning ignited gas seeping from the ground. Moving it to where it was needed was the next problem, and the Chinese were the first to solve it, using pipes made from bamboo.
In the UK, gas lighting was first used in 1792 by the engineer William Murdoch, and the technology quickly spread to light streets across the country. Today gas does far more than heat homes and cook food. It is also used in making vinyl flooring, carpets, deodorant and mobile phones. As the country looks to reduce its dependence on fossil fuels, alternatives such as heat pumps are becoming part of the picture.
Fixing common radiator and boiler faults
A few common heating faults can be dealt with at home. A radiator that is only warm at the bottom or on one side usually has an air pocket. Use a radiator key to loosen the bleed valve in a top corner until air hisses out, then tighten it again as soon as water appears. If some rooms are warm and others are not, the radiators probably need balancing, by adjusting the valve on the pipe at a bottom corner. Expect some trial and error.
If that does not work, rust or sludge may be blocking the system, and flushing it is a tricky job best discussed with a plumber first. Kettling, a rumble like boiling water, is caused by sludge or limescale in the heat exchanger and wastes energy, so it needs a chemical flush.
When a combi boiler stops in freezing weather, check that the condensate pipe running through the outside wall has not frozen. Thawing it is often all that is needed. A boiler that keeps switching off can have several causes, from low pressure to a faulty pump, so a plumber may need to diagnose it.