A full central heating installation normally includes a heating survey and system design, a boiler, radiators and valves, pipework, heating controls, system flushing, pressure testing, balancing, commissioning and certification. The exact list depends on your property, whether you already have a system, and the type of boiler you choose.
If you are comparing quotes, this is the key point. A boiler replacement swaps one appliance and reuses your existing pipes and radiators. A full central heating installation builds or rebuilds the whole system. Those two jobs can differ by thousands of pounds, so it pays to know exactly what each quote covers.
This guide explains what you are paying for, what usually costs extra, how long the work takes, and what to look for in a London heating quote.
What Is Included in a Full Central Heating Installation?
A full installation covers seven main parts: survey and design, boiler, radiators, pipework, controls, flushing and testing, and commissioning with certification. Here is what each one involves.
Heating Survey and System Design
A proper installation starts with a survey, not a price. The engineer visits your home to check what your heating needs are and how the system should be laid out.
A good survey covers:
- Room sizes, wall types, windows and insulation
- A heat-loss calculation for each room
- Where radiators should go
- Boiler sizing, so the boiler is not too big or too small
- Possible pipework routes
- Your hot water demand (how many bathrooms, how many people)
- The condition of any existing system
Correct radiator sizing matters. A radiator that is too small will not keep a room warm. Oversized equipment wastes money and can make the boiler work less efficiently.
Boiler Supply and Installation
The boiler is normally included in a full installation, but check the quote to be sure. There are three common types:
| Boiler type | How it works | Best suited to |
|---|---|---|
| Combi boiler | Heats water on demand. No hot water cylinder needed. | Flats and smaller homes with one or two bathrooms |
| System boiler | Works with a hot water cylinder. Supplies several taps at once. | Larger homes with two or more bathrooms |
| Heat-only (regular) boiler | Works with a cylinder and a loft tank. | Homes with an older open-vented system |
Installing the boiler also includes the flue (the pipe that carries fumes outside), the condensate pipe (which drains acidic water from a condensing boiler), and the gas and water connections.
If you want to compare options, see our guides to combi boiler installation in London and system boiler installation in London.
Radiators and Radiator Valves
Radiators are included in a new central heating system, but the number, size and style should be listed in your quote. In a first-time installation, every radiator is new. In an upgrade, some existing radiators may be reused if they are in good condition.
This part usually includes:
- Panel radiators, sized for each room
- Towel rails in bathrooms where needed
- Thermostatic radiator valves (TRVs) to control the heat in each room
- Lockshield valves, which help balance the system
As a rough guide, a typical 3-bedroom house often has around 8 to 10 radiators. Your own number depends on room sizes and layout.
Central Heating Pipework
Pipework connects the boiler to every radiator, and it is part of a full installation. It includes:
- Flow and return pipes that carry hot water out and bring cooler water back
- Connections at each radiator and at the boiler
- Gas pipework to the boiler, where the existing supply needs altering
- The condensate pipe
Pipes can be run under floors, through walls, or on the surface. Surface pipes are quicker and cheaper but more visible. In period properties and Victorian houses, floors and walls can make routing harder, which affects the time and price.
Heating Controls and Thermostat
A new central heating system normally includes basic controls: a programmer, a room thermostat and TRVs. These let you set when the heating comes on and how warm each space gets.
Options include:
- A standard programmer and room thermostat
- A smart thermostat, which you control from your phone
- Heating zones, so you can heat upstairs and downstairs separately
In England, new gas boiler installations must meet “Boiler Plus” efficiency rules, which include time and temperature controls. Your engineer should choose controls that are compatible with your boiler. See our smart thermostat installation service for more.
System Flushing, Testing and Balancing
Flushing, testing and balancing are part of a proper installation, not optional extras. They protect the system and make it work well.
- Flushing removes debris and sludge. This is especially important when connecting a new boiler to old pipes.
- Chemical inhibitor is added to reduce corrosion and scale.
- A magnetic filter is usually fitted to catch metal particles.
- Pressure testing checks for leaks before the system goes live.
- Gas tightness testing checks the gas supply.
- Balancing adjusts the radiator valves so every radiator heats evenly.
If your existing system is very dirty, you may need power flushing as well.
Commissioning and Certification
Commissioning means the engineer starts up the system and checks it against the manufacturer’s instructions. They should complete the Benchmark commissioning checklist and leave you with the paperwork.
Gas boiler work must be done by a Gas Safe registered engineer. After the job, you should receive:
- The completed Benchmark checklist
- Notification to building control through the Gas Safe Register, so the work meets Building Regulations
- A Building Regulations compliance certificate (issued after notification)
- Manufacturer warranty details and registration information
- User guides for the boiler and controls
Keep these documents safe. You will need them if you sell your home or make a warranty claim.
Boiler Replacement vs Full Central Heating Installation
A boiler replacement swaps the boiler only. A full installation also includes radiators, pipework, controls and system design.
| Boiler replacement | Replacement of an existing system | First-time installation | |
|---|---|---|---|
| Boiler | New | New | New |
| Radiators | Reused | Some or all new | All new |
| Pipework | Reused | Partly replaced | All new |
| Controls | Often upgraded | New | New |
| Survey and design | Basic check | Full survey | Full survey and design |
| Typical time | About 1 day | About 2 to 5 days | About 4 to 8 days |
The time ranges above are typical. Access, property size and any extra work can change them.
First-Time Central Heating Installation
First-time installation means fitting a complete wet heating system in a home that has none. Examples include a flat or house with electric heaters, or a property with no radiators at all.
This is the biggest version of the job. The installer must:
- Design the whole system from scratch
- Fit the boiler, flue and any cylinder
- Run new pipework to every room
- Install radiators and valves
- Fit controls and test everything
It also often needs extra checks, such as whether your gas supply is large enough for the boiler. If you have no gas connection at all, that is arranged separately with your gas network and is not usually part of the installer’s price.
Because so much work is involved, first-time installs take longer and cost more than upgrades. They also add the most comfort, so it is worth planning them carefully.
What Is Usually Not Included?
Most quotes do not include building work, decorating or property-specific extras. Ask about each of these before you accept a price:
- Major structural changes
- Extensive plastering and decorating after pipework
- Flooring repairs or replacement
- Difficult access, such as solid floors or hidden routes
- Gas supply upgrades
- Electrical upgrades
- Extra radiators added after the original design
- Major flue changes
- Moving or replacing a hot water cylinder
- Asbestos removal, if it is found
- Parking or congestion costs, which can apply in some London areas
Good installers explain these at the survey stage. Be cautious of a quote that says nothing about extras.
How Much Does Central Heating Installation Cost in London?
Cost depends mainly on the size of your home, the number of radiators, the boiler type and how easy it is to run pipework. London prices are often higher than the national average because of labour rates, access and parking.
As a general guide, published UK cost guides put a typical gas central heating system at roughly £4,000 to £6,000 nationally, and London quotes are often higher depending on the property and scope.
What changes the price most:
- Property size and number of rooms
- Number and size of radiators
- Boiler type and output
- Amount of new pipework needed
- Your existing system: a first-time install costs more than an upgrade
- Access: floors, walls and loft or cupboard space
- Controls: smart or zoned controls add cost
- Specification: brand, warranty length and extras
For a fuller breakdown, see our central heating installation cost guide for London.
How Long Does Central Heating Installation Take?
A full central heating installation usually takes around 4 to 8 days, depending on the property and the work involved.
- Upgrading an existing system: often about 2 to 5 days, because much of the pipework and many radiators can stay.
- First-time installation: often 4 to 8 days, or longer in large homes. The extra time covers new pipework, radiators, controls, testing and commissioning.
- Boiler-only replacement: usually about a day.
Ask your installer for a day-by-day plan, including how long you will be without heating or hot water.
What Happens on the Day of Installation?
Installation follows a set order, from protecting your home to handing over your paperwork. A typical job looks like this:
- Preparation. The team lays dust sheets and protects floors and walls.
- Isolation and removal. Any old boiler or radiators are drained and taken out.
- Boiler installation. The new boiler, flue and condensate pipe are fitted.
- Radiator installation. New radiators and valves are mounted.
- Pipework. Flow and return pipes are run and connected.
- Controls. The thermostat, programmer and any smart controls are installed.
- Filling and flushing. The system is filled, flushed and treated with inhibitor.
- Testing. Pressure and gas tightness tests are carried out.
- Balancing. Radiators are adjusted so they heat evenly.
- Commissioning. The boiler is set up and checked against the manufacturer’s instructions.
- Certification. The engineer completes the Benchmark checklist and notifies the Gas Safe Register.
- Handover. You get a walk-through, the paperwork and a demonstration of the controls.
Practical tips: clear access to rooms, cupboards and the loft, move fragile items, and plan for a period without heating, especially in winter.
What Should Be Included in a Central Heating Quote?
A good quote lists every part of the job clearly, so you know what you are paying for. Use this checklist when comparing quotes:
- Boiler make and model
- Boiler output (kW)
- Number of radiators
- Radiator sizes and types
- Radiator valves (TRVs and lockshield)
- Pipework
- Controls and thermostat
- Flue
- Magnetic filter
- System flushing
- Inhibitor
- Commissioning
- Certification and paperwork
- Warranty length and conditions
- Waste removal
- Making good (patching and tidying)
- Labour
- VAT
- Any exclusions, stated in writing
If two quotes have very different prices, compare them line by line. The cheaper one may leave out flushing, a filter or making good.
Frequently Asked Questions
What is included in a central heating installation?
A full installation normally includes a survey and design, a boiler, radiators and valves, pipework, heating controls, flushing, testing, balancing, commissioning and certification.
Does central heating installation include the boiler?
Usually yes for a full installation. A boiler is a core part of the system. Always confirm the make, model and output in your written quote.
Are radiators included in a new central heating system?
Yes, in a first-time installation. In an upgrade, some existing radiators may be reused if they are in good condition. The quote should state the number and sizes.
Does central heating installation include pipework?
Yes. A full installation includes flow and return pipes, radiator and boiler connections, and the condensate pipe. Extra pipework caused by difficult access may cost more.
Does central heating installation include a thermostat?
Normally yes. A room thermostat and programmer are standard, and TRVs control individual rooms. Smart thermostats and zoning are often upgrades.
Does a new central heating system need to be flushed?
Yes. Flushing removes debris, and an inhibitor protects against corrosion. It is especially important when new equipment connects to an older system.
How long does central heating installation take?
Typically 4 to 8 days for a full installation. Upgrading an existing system is often quicker, and a boiler-only swap is usually about a day.
How much does central heating installation cost in London?
It depends on property size, radiators, boiler type, pipework and access. London prices are often above the national average, so get a written, itemised quote after a survey.
Can central heating be installed in a house with no existing system?
Yes. This is called a first-time installation. The installer designs and fits the whole system, including the boiler, radiators, pipework and controls.
Do I need a Gas Safe registered engineer for a gas central heating installation?
Yes. By law, gas work must be done by a Gas Safe registered engineer. You can check an engineer’s registration on the Gas Safe Register website.
What certificate do I receive after central heating installation?
You should receive the Benchmark commissioning checklist and a Building Regulations compliance certificate, which is issued once your Gas Safe engineer notifies the work. You should also get warranty details.
What can increase the cost of central heating installation?
Difficult access, extra radiators, gas or electrical upgrades, flue changes, cylinder moves, asbestos, and plastering or flooring repairs can all raise the price.
Conclusion
A full central heating installation is more than a new boiler. It is a designed system: boiler, radiators, pipework, controls, flushing, testing, commissioning and certification, all done by a Gas Safe registered engineer.
Before you accept a quote, check that each of those parts is listed and that any exclusions are clear. That way you know exactly what you are paying for and avoid surprises later.
Planning a new system in London? Book a free survey and get a clear, itemised quote that shows what is included, what is not, and how long the work will take.