Does My House Have Enough Power for a Heat Pump?

The Short Answer

Most UK homes already have enough electrical capacity for a heat pump, so this is rarely a reason to rule one out. Before installation goes ahead, your installer is required to calculate the property's maximum electrical demand as part of the design process. If the calculated demand comes out at 60 amps or below, the installation will often qualify for the quicker Connect and Notify route with your local Distribution Network Operator. If it comes out above 60 amps, the installer will normally need to Apply to Connect and get approval from the DNO before installation can proceed. This doesn't mean your home can't have a heat pump; it simply means approval needs to happen first, and it's a normal, routine part of a properly planned installation rather than a red flag.

Does a 10 kW Heat Pump Use 10 kW of Electricity?

No, and this is one of the most common misunderstandings homeowners have when they first see a heat pump's specification sheet. A heat pump's quoted output figure is its heating output, the amount of heat it delivers into your home, not its electrical consumption. Heat pumps work by moving heat from the outside air into your home rather than generating heat directly from the electricity they consume, which is the whole basis of how they achieve efficiency ratios well above 100%. As a result, the electrical demand a heat pump actually draws from your supply is usually considerably lower than its stated heating output, often by a factor of three or four depending on outdoor temperature and the system's coefficient of performance at that moment.

How Is Maximum Demand Calculated?

There isn't a single legal formula that every installer is required to use, which is part of why this calculation is sometimes skipped or done poorly on rushed jobs. Simply adding together the rated capacity of every breaker in your consumer unit would produce a wildly unrealistic and unusably high figure, because it's extremely unlikely that every single circuit in your home, the cooker, the sockets, the lighting, the immersion heater, and everything else, would ever be drawing its full rated load at exactly the same moment.

One method recommended by Heat Geek, and a good practical way to get a quick, realistic estimate, works like this: take 100% of the largest single breaker in the consumer unit, then add 40% of every other breaker in the property, including the proposed heat pump's own circuit.

As a worked example, imagine a consumer unit with a 40A cooker circuit, 32A sockets, 20A sockets, two 6A lighting circuits, and a proposed 16A heat pump circuit. The largest breaker, the 40A cooker circuit, is counted in full. The remaining circuits add up to 80A combined, and 40% of that 80A works out at 32A. Added together, that gives an estimated maximum demand of 72 amps. Since this exceeds the 60 amp threshold, the installer would normally need to Apply to Connect with the DNO before the installation could go ahead.

This method gives a genuinely useful, realistic estimate of maximum demand, but a competent electrician should still look individually at any particularly large loads on the property, such as electric showers, EV chargers, or immersion heaters, since these can behave differently to smaller everyday circuits and sometimes need separate consideration rather than being folded into the standard 40% calculation.

Can I Still Have a Heat Pump If I'm Above 60 Amps?

Yes, absolutely. Going above 60 amps on the maximum demand calculation doesn't mean the installation has been refused or that a heat pump isn't suitable for your home. It simply means the DNO needs to assess the capacity of the local electricity network before the heat pump is connected, which is the Apply to Connect route rather than the quicker Connect and Notify one. In many cases, the DNO will simply approve the installation as proposed, or in some instances arrange to upgrade the property's main service fuse, which is a relatively routine piece of work rather than a major undertaking. It's worth understanding this process properly if you're at the planning stage, and we've covered how the wider DNO relationship works, including what Connect and Notify and Apply to Connect actually mean in practice, in our article on informing the electricity grid before installing a heat pump.

Who Deals With the DNO?

Normally, this is entirely your installer's responsibility, not something you need to manage yourself. A competent, MCS-certified installer should calculate the property's maximum electrical demand properly using a recognised method rather than a rough guess, decide whether your specific installation falls under Connect and Notify or Apply to Connect, submit whatever paperwork the DNO requires on your behalf, and explain clearly if any supply upgrades are needed before work can proceed. If any of these steps feel like they're being glossed over or rushed during your quoting process, it's worth treating that as a warning sign about the wider quality of the installation being proposed, in the same way we cover in 7 signs your heat pump may not be installed correctly and common commissioning mistakes with air source heat pumps.

Why Getting the Electrical Side Right Matters Alongside System Sizing

The electrical demand calculation doesn't exist in isolation; it sits alongside correct heat pump sizing as one of the core checks that should happen before installation. An oversized heat pump doesn't just run less efficiently and cost more to buy, as covered in what happens if a heat pump is oversized, it also pushes your maximum demand calculation higher than it needs to be for a property that never required that much heating capacity in the first place. Getting the heat pump correctly matched to your home's actual heat loss, covered in what size heat pump does my house need, keeps both the running costs and the electrical demand calculation as low as they realistically can be, which occasionally makes the difference between qualifying for Connect and Notify and needing to Apply to Connect in the first place.

Thinking About Installing a Heat Pump?

Our Pre-Installation Design Review checks the proposed system in full before installation goes ahead, helping identify potential electrical demand issues, sizing problems, or design shortcuts before you commit to a quote. It's also worth browsing our case studies if you want to see real examples of what gets missed when this stage of planning is rushed.

Already Have a Heat Pump?

Our Fix My Heat Pump service provides independent remote technical support to help diagnose faults and performance problems, whether that's related to electrical setup, controls, or system design, before an engineer needs to attend in person.

Final Thoughts

Most UK homes already have enough electrical capacity to support a heat pump comfortably. The important step is calculating the property's maximum demand correctly, using a sensible method rather than simply adding together every breaker in the consumer unit and assuming the worst. If the demand stays at or below 60 amps, the installation will often qualify for Connect and Notify and can proceed quickly. If it exceeds 60 amps, your installer will normally need DNO approval before the installation can go ahead, which adds a step to the process but is very rarely a reason the installation can't happen at all.