Does a heat pump need an electrical upgrade?
Short answer
Sometimes, but not always. Your installer should calculate the home’s maximum electrical demand and check the main fuse, consumer unit and other large loads such as EV chargers. A large heat pump can have a much lower electrical input than its heating output, so the kW on the heat-pump nameplate is not the same as its normal electricity draw.
Last checked 24 September 2026 · 2 sources
How much electricity does a heat pump draw?
It depends on the model, outdoor temperature and operating conditions.
In the source interview, a 16 kW heat pump was described as drawing roughly 4 kW in normal operation, with a higher allowance used for worst-case electrical calculations.
That example should not be copied to every installation. A smaller domestic unit may draw much less.
What does the installer check?
A competent installer should carry out a maximum-demand assessment.
That looks at the heat pump alongside other significant electrical loads, including:
- EV chargers;
- electric showers;
- induction hobs;
- immersion heaters;
- batteries and inverters;
- other high-load appliances.
The aim is to make sure the property’s supply can safely support the expected demand.
Will I need a bigger main fuse?
Possibly.
If the calculated demand is too close to the rating of the existing supply, the Distribution Network Operator may need to upgrade the service fuse or supply.
This is especially relevant in homes adding several electric technologies at once, such as a heat pump and EV charger.
Is G98 or G99 approval needed?
G98 and G99 are primarily connection rules for electricity generation equipment. A heat pump is a load, not a generator.
The source interview correctly separates the heat-pump electrical demand from solar-generation connection rules. Your installer may still need to notify or liaise with the local Distribution Network Operator about the added electrical load.
What should I do next?
Ask your installer for the maximum-demand calculation and whether any DNO work is included in the quote. If you plan to add an EV charger, battery or induction cooking later, mention that now.
Sources
- Source interview with Heat Geek installer, electrical-demand and DNO discussion.
- MCS installation standards and DNO connection processes, checked 24 September 2026.
Last checked: 24 September 2026