Central Heating Installation

Most UK homes have a "wet" system: a heat source warms water, and a pump circulates it to radiators or underfloor heating. A full installation covers:

• The heat source: Usually a gas boiler, fitted through our boiler installation service by Gas Safe registered engineers, as the law requires. A heat pump is the main low-carbon alternative.
• Pipework: Flow and return pipes to every room, sized for the heat each room needs.
• Emitters: Radiators sized room by room through our radiator installation and replacement service, or underfloor heating installation in kitchens, extensions and bathrooms. Many homes use both.
• Hot water: Either instantly from a combi boiler, or from a hot water cylinder heated by the system.
• Controls: A programmer or smart thermostat, room thermostats and thermostatic radiator valves, through our thermostat and heating control installation service.
• Protection: A magnetic filter on the return pipe and inhibitor in the water to slow corrosion and sludge.

There is no single best type. The right choice depends on how many bathrooms you have, how much hot water you use at once, your mains water pressure and the space available.

An unvented cylinder must be fitted by someone qualified to install one under the building regulations. Heat pumps work best at lower water temperatures, so radiators and pipework are sized for that from the start. The Boiler Upgrade Scheme in England offers a grant towards a heat pump.

First we work out the heat loss of each room: the heat it loses through walls, windows, floor, roof and ventilation. That figure sets the output of each radiator or underfloor zone, the size of the boiler or heat pump, and the size of the pipes.

Getting this right avoids cold rooms with undersized radiators, and an oversized boiler that switches on and off constantly. The building regulations also expect new heating systems to be designed so that they can run efficiently at lower flow temperatures where practical, which suits both condensing boilers and heat pumps.

Partly, but most installations lift some floorboards. Pipes have to reach every radiator, and the neatest and most efficient route is usually under the floor or through ceiling voids. The options are:

• Under suspended timber floors: Boards are lifted along the pipe runs, and flexible plastic pipe can often be threaded through the joists with fewer boards lifted.
• Through the ceiling below: For upper floors, pipes can drop from the loft or run in ceiling voids.
• On the surface: Neat surface-mounted pipes along skirting boards, boxed in where needed. Useful on solid concrete floors.

Typical pipe sizes are 22 mm for main runs and 15 mm to radiators. Copper and plastic both have their place, as our pipework installation and repair page explains. Because we are builders, lifted floors are relaid and any wall chases are made good.

Installing a new heating appliance is notifiable building work, either through a competent person scheme or a building notice; for a gas boiler, the Gas Safe registered engineer who fits it normally notifies building control. The system must also meet the energy efficiency rules, including suitable time and temperature controls.

At the end, the system is flushed, filled with inhibitor in line with BS 7593 (the standard for system water treatment), balanced and commissioned. You receive the Benchmark commissioning checklist and the building regulations compliance certificate. If you are replacing an old system and keeping some of it, our power flushing service cleans the parts that stay.