Gas / electric boiler removal

The process is similar for gas and electric boilers. The main difference is what the boiler is disconnected from and who is allowed to do it. The engineer usually works in this order:

1. Switches the boiler off, isolates it from the electricity supply and checks that the terminals are dead.
2. On a gas boiler, closes the gas supply to the boiler and checks the main gas valve.
3. Closes the valves on the heating pipes and drains the boiler, or the whole system if needed.
4. Disconnects the cold and hot water pipes if the boiler also heats water for the home.
5. Separates the heating pipes and labels each one so the new boiler is connected correctly.
6. Disconnects the controls, room thermostat, sensors and other accessories.
7. On a gas boiler, disconnects the flue.
8. Releases the boiler from its wall bracket or the floor and carries it out safely, a larger boiler sometimes in pieces.
9. Caps the pipe ends and, for gas, checks that they are tight.

If the new boiler is not fitted straight away, the system should be left safe: gas capped, cable safely terminated and pipes closed off.

Any work on a gas appliance must be done by a qualified, registered gas engineer. This is not a formality. If the pipework is disconnected incorrectly, gas can leak and cause an explosion. A badly sealed flue can let combustion gases flow back into the room.

After closing the supply, the engineer disconnects the gas pipe, caps the end and carries out a tightness test. You should get a written record that the gas appliance has been disconnected. It is useful when the new boiler is fitted, during later safety checks and if your building management or owners' association asks for it.

In a block of flats, it is worth telling the building management in advance, especially if the boiler is connected to a shared flue or the gas has to be turned off briefly in several flats. If you will not use gas at all any more, ask your gas supplier and network operator how to end the supply and what happens to the meter.

If you smell gas, do not use light switches or naked flames. Open the windows, leave the room and call the gas emergency number of your network operator or the emergency number 112.

An electric boiler draws a lot of power and is often connected to its own circuit, sometimes three-phase, straight from the consumer unit. Only a qualified electrician should disconnect it. They find the right circuit breaker, switch it off, confirm the circuit is dead and then safely terminate the cable or disconnect it at the consumer unit.

It makes sense to have the breakers and supply cables checked at the same time. If another heat source follows, such as a heat pump, the electrician can tell you straight away whether the existing supply and protection are suitable.

One thing people often forget: electric heating is frequently linked to a special electricity tariff, such as an off-peak or heating tariff. Once the boiler is gone, check with your electricity supplier whether you keep that tariff or need to change it.

Every removal is different, and that decides how much work it takes. The job is much easier with:

• Isolation valves under the boiler, so the whole system does not need draining
• Good access to the boiler and a clear route to carry it out
• A simple setup with one heating circuit
• A wall-hung boiler in a flat or on the ground floor

It takes more time and care with:

• An old floor-standing cast-iron boiler, which is heavy and often has to be taken apart
• A boiler room in a cellar with a narrow staircase
• Several heating circuits, a hot water cylinder and more complex controls
• Rusted or seized joints, or missing valves
• An old flue that may be made of asbestos cement

If you suspect asbestos, do not touch it yourself. Materials containing asbestos must be removed by a licensed specialist contractor.

If the replacement also changes the gas pipe route, the chimney or the way flue gases are discharged, check with your local building authority whether you need permission or have to notify them. Rules vary from place to place, so it is better to ask before work starts.

• The boiler is disconnected from the gas without capping the pipe and testing it for leaks
• The heating pipes are not labelled and get mixed up when the new boiler is connected
• Drained water containing antifreeze goes down the drain instead of being disposed of properly
• The chimney is forgotten and left open or poorly sealed
• The old boiler ends up next to a skip instead of at a collection point

In practice, removal often reveals leaking joints, sludged-up pipes or worn valves. It is best to deal with these straight away while the system is drained, not after the new boiler is running.

An old boiler does not belong in household waste. It contains metals, electronics and other parts that should be recycled. Scrap metal dealers take the metal parts, and the electronics count as electrical waste. You can also take it to your local recycling centre, where they will tell you under what conditions they accept it.

The simplest option is to agree that the contractor takes the boiler away and disposes of it. For larger renovations, ask for a waste transfer or disposal receipt. The owner of the appliance is responsible for making sure it is disposed of correctly.

• The gas pipe end is capped and you have a record of the tightness test
• The supply cable is safely terminated or disconnected at the consumer unit and the breaker is labelled
• The heating pipes are closed off, capped or clearly labelled for the new boiler
• No water is dripping from the pipes and the floor is dry
• The flue opening is sealed or ready for the new flue
• The old boiler has been taken away and you know where it was disposed of
• The area is clean and ready for the new appliance