Heat Pumps and Your Electrics: What a London Home Needs First

More London homeowners are swapping gas boilers for air source heat pumps. A heat pump is mainly a heating job, but it is also one of the biggest electrical loads a home can take on, and the electrics need to be ready before the installer arrives. This guide explains the electrical side in plain terms, so you know what to ask.

The heat pump's own supply

The outdoor unit needs a dedicated circuit from the consumer unit, usually with an outdoor isolator switch next to the unit so it can be safely switched off for servicing. The cable route from the board to the outside wall needs planning, especially in terraced houses where the board is at the front and the unit goes at the back.

Hot water cylinder and backup heaters

Most heat pump systems include a hot water cylinder with an electric immersion heater, used as a backup and for regular high temperature cycles. Some systems also have a backup heater for the heating. Each of these adds load and may need its own circuit and controls.

Main fuse and network notification

Heat pumps must normally be notified to the network operator, and in some homes the main fuse or service cable may need upgrading, especially where there is already an electric shower or an EV charger. Our guide on whether your main fuse is big enough explains how capacity is checked.

The consumer unit

Older boards often have no spare ways and no suitable RCD protection for the new circuits. Replacing the board before the heat pump goes in is usually simpler and cheaper than doing it halfway through. Our guide to getting the consumer unit checked first covers this alongside solar and smart meters.

Earthing and bonding

New pipework and metal parts may need bonding, and the earthing arrangement must be suitable for the new equipment. Our guide to earth bonding explains why this matters.

Grants and paperwork

Government grant schemes can help with the cost of a heat pump in England, but the heating installer usually handles the application. Make sure you receive an Electrical Installation Certificate for any new circuits, and keep it with the heat pump commissioning paperwork.

Book a pre-installation check

Energy North Ltd checks supplies, boards and earthing ahead of heat pump installations across North, East and West London with City & Guilds certified electricians. See our EICR service.