Hybrid heat pumps

There are several reasons an installer might suggest fitting a hybrid heat pump system:

Your home’s heat demand is the amount of heat required to provide heating and hot water. A single heat pump on a domestic electricity supply might not be able to provide enough heat to keep properties with a high heat demand to a comfortable temperature.  

Having radiators or under floor heating help a heat pump to run at a high efficiency, keeping running costs to a minimum. You could also reduce your heat demand through improved insulation. We have more information on insulation and draught-proofing. 

But if you live in a large home where insulating is either impractical or too expensive, your installer may suggest a more specialist solution.

This might include installing either a hybrid heat pump, a high-temperature heat pump or a twin heat pump installation (often referred to as a cascaded heat pump system).

It’s worth finding out what it would cost to upgrade your electricity supply to a three-phase supply, which offers more electrical power. If this is an affordable option, it greatly improves your electricity options for both heat pumps and electric vehicle charging.

Your district network operator is responsible for upgrades to your supply. You can ask your installer to help you get a quote.

Replacing your boiler with a heat pump can result in lower heating bills, but this depends on the efficiency of the boiler and the fuel you’re replacing. For example, a modern gas boiler could deliver heat at a cheaper cost than a heat pump when gas prices are low.

Some hybrid systems have controls that automate when and how the heat pump operates based on several inputs, including:

• Electricity costs.
• Fossil fuel supply costs (mains gas, LPG or oil).
• Time of day, if this has an impact on electricity prices.
• Whether a solar panel system at the same property is generating or exporting energy.

Configuring the hybrid system to react to fuel prices should mean that the boiler only operates when it’s cheaper to run than the heat pump. This should lower your overall running costs compared to running the fossil fuel boiler or heat pump alone.

If you’re considering a hybrid system for this reason, it’s important to check the assumptions used by your installer in deciding when the heat pump will run vs the boiler.

For example, you should review the gas and electricity tariffs and compare them to what you’re paying now, and what you expect to pay in the future. Speak to your installer about the heat pump configuration and ask them to explain their running cost calculations.

The two most likely configuration options would be:

The exact design and configuration largely depend on the reason for choosing a hybrid heat pump system. Regardless of the reason, your installer should provide:

• Running costs for the designed system.
• Assumptions of heat pump efficiency, boiler efficiency and fuel prices.

The exact configuration you choose is typically decided after discussion with your installer, during system design. The more cost-effective or carbon saving configuration depends on your home and heating needs.

Your motivation for installing a hybrid heat pump may determine the most suitable configuration. But be aware that some installers may not offer all the options you want to consider.

We always recommend that you get quotes from at least three installers, including their opinion on the most suitable system for the property and your requirements.

Other considerations include the cost of maintaining a hybrid system. For comparison, you need to understand your current heating system running costs.