Heat From Air
Hybrid Heat Pumps
What is a hybrid heat pump?
If you’re looking for lower-carbon heating or reduced energy bills, consider installing a hybrid heat pump system. A hybrid system may be a good option if a standard heat pump installation isn’t suitable for your needs.
The term ‘hybrid heat pump’ refers to a system that uses a heat pump alongside another heat source. Typically, it describes fitting a heat pump alongside a fossil fuel (gas, oil or LPG) boiler. This boiler could be an existing boiler, or you could be considering installing a new boiler at the same time as the heat pump.
Is a hybrid heat pump right for me?
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.
Well specified heat emitters (radiators or UFH) will 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.
However, if you live in a large home where insulating is either impractical or too expensive, and a single heat pump would not cope with the high heat demand, 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).
Generally, the largest size of heat pump you can install on a standard (single phase) domestic electricity supply is 14kW. However, using either a hybrid, high temperature or cascade system you can find a solution for heating most homes.
It’s always worth finding out what it would cost to upgrade your electricity supply to a three-phase supply. If this can be done at an affordable cost, it will greatly improve your electricity options for both heat pumps and electric vehicle charging.
Replacing a boiler with a heat pump can result in lower heating bills, however this depends on the efficiency of the boiler and the fuel you are replacing. For example, a modern gas boiler could deliver heat at a cheaper cost than a heat pump when mains 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 photovoltaic (PV) system at the same property is generating or exporting energy.
Configuring the hybrid system to react to fuel prices ensures the boiler runs only when it’s cheaper than the heat pump. This lowers overall running costs compared to using the fossil fuel boiler or heat pump alone.
If you’re considering a hybrid system, check your installer’s assumptions on when the heat pump versus the boiler will run. Review your gas and electricity tariffs and compare them to current and future costs. Speak to your installer about the configuration and ask them to explain their running cost calculations.
The two most likely configuration options would be:
Running the boiler as a ‘top-up’ system during very cold weather when the heat pump cannot supply enough heat. The boiler may also assist with hot water production based on tariff costs.
Separating hot water and space heating functions allows the boiler to supply hot water, while the heat pump handles space heating. If using a combi boiler, this removes the need for a hot water cylinder.
Designing your hybrid heat pump system.
The exact design and configuration will largely depend on the reason for choosing a hybrid heat pump system. However, regardless of the reason, your installer should provide running costs for the designed system, as well as assumptions of heat pump efficiency, boiler efficiency and fuel prices that were used in that calculation.
The exact configuration chosen is typically decided after discussion with your installer, during system design. The more cost-effective, or more carbon saving, configuration will depend on your home and heating needs. Your motivation for installing a hybrid may determine the most suitable configuration but be aware that some installers may not offer all the options you might want to consider.
We always recommend that you get quotes from several 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, and for comparison, you will need to understand your current heating system running costs.
Further Reading...
Your Green Future
Starts Here
Your green future
starts here...
Your Green Future
Starts Here
Your green future
starts here...