Heat Pumps

Heat Pump Electrical Requirements: What Your Home Actually Needs

With the Boiler Upgrade Scheme still offering £7,500 off an air source heat pump, more Kent homeowners are switching from gas — and finding out partway through that it's an electrical job as much as a heating one. Here's what's actually involved.

Why does a heat pump need an electrician at all?

A gas boiler is a small, low-power appliance on a simple fused connection. A heat pump runs almost constantly through the colder months and pulls a lot more current — a typical domestic air source unit draws somewhere in the region of 15–30 amps at start-up, several times what a boiler needs. It needs its own dedicated circuit, its own isolator, and a consumer unit that can actually take the extra load. None of that is something a heating engineer signs off on their own — it's notifiable electrical work in its own right.

What electrical work is typically required?

• A dedicated circuit from the consumer unit, sized to the manufacturer's specification for that specific heat pump model
• A weatherproof isolator switch mounted outside next to the unit, so it can be safely isolated for servicing
• RCD/RCBO protection on that circuit, matching current wiring regulations
• Consumer unit capacity check — is there a spare way, and can the unit as a whole actually take the extra load?
• Cabling to the indoor controls/cylinder if the heat pump has a separate hot water cylinder with its own immersion backup
• Earthing and bonding checks to current standards, since this is exactly the kind of work that surfaces an older installation's shortfalls

Does my consumer unit need upgrading first?

Often, yes. Many homes having a heat pump fitted still have an older consumer unit that's either full, has no RCD protection at all, or simply wasn't sized with an appliance like this in mind. Your electrician will do a load calculation as part of the job — factoring in the heat pump alongside everything else already running in the house — before confirming whether the existing board can take it or needs replacing.

Will my electricity supply need upgrading?

For most single heat pump installations on a standard single-phase domestic supply, no — the existing supply is enough. It becomes a real question on larger properties, homes already running other high-demand electrical loads (an EV charger and a heat pump on the same supply is a common combination that needs checking), or larger heat pump units. In those cases your installer needs to check the installation against the DNO's (District Network Operator's) connection limits, and may need to notify or apply to the DNO before the heat pump goes live — this is a standard part of a properly planned installation, not something to find out about afterwards.

Is it notifiable work?

Yes. A new circuit from the consumer unit for a fixed appliance like a heat pump is notifiable under Part P of the Building Regulations, the same as a garden room supply or a full rewire. It must be notified to your local building control office before work begins, and you should receive an Electrical Installation Certificate on completion — keep this with your MCS certificate for the heat pump itself, as both may be needed for warranties, resale, or a future Boiler Upgrade Scheme-adjacent grant.

How long does it take?

The electrical side of a straightforward heat pump installation typically takes half a day to a full day on-site, run alongside the heating engineer's own installation timeline. It takes longer if a consumer unit replacement or supply-related work is needed too — your electrician will confirm this after the initial assessment.