Many homes are currently served by oil heating systems, but oil boilers aren’t the most environmentally friendly appliances and homeowners may want to switch to a system that doesn’t rely on burning fossil fuels.
For now, air source heat pump can be considered to be the future of heating a home, and through renovating a home, or simply looking for a greener heating option, an air source heat pump can be considered high on the list as a potential replacement.
An air source heat pump can typically replace an oil boiler and potentially be a more efficient and effective heating system, provided that certain factors are met such the right internal heating equipment also being installed and that the property is well insulated.
Our own air source heat pump didn’t replace an oil boiler but was installed when the house was built. Our previous house did however use an oil boiler and so we’re familiar with both forms of heating systems and what is required to be able to replace an oil boiler with a heat pump.
In the rest of this article we discuss how air source heat pumps operate, their benefits over oil heating systems, and how an air source heat pump system could replace an oil one.
What Is An Air Source Heat Pump?
An air source heat pump is a device that uses refrigerant to help extract heat from the outside air and transfer it inside. The most common application for an air source heat pump is in space heating in homes and buildings.
Air source heat pumps can also be used for cooling purposes and are able to provide domestic hot water (when either are accompanied with the right indoor setup).
As air source heat pumps extract heat from outside air, or dispel heat outside when in cooling mode, external air source heat pump units need to be located in a suitable outdoor location.
For example, our air source heat pump sits down the side of our house.
We have another article that explains air source heat pumps in more detail.
How An Air Source Heat Pump Works
An air source heat pump works by harnessing the temperature differential between outdoor air and indoor air. It also leverages the compression and expansion of gas to generate as much heat as possible from the air.
The simplest type of air source heat pump consists of a compressor, an outdoor coil and indoor coil, and an expansion valve.
The refrigeration cycle begins with the compressor, which helps to increase the temperature of refrigerant gas that has evaporated from a liquid through extracting heat from outside air within the outside coil.
This heated gas delivers heat into a home to the indoor coil where heat is provided to a home either through space heating as air to air system or through central heating as an air to water system.
For more information see our main article on how an air source heat pump works.
What Is An Oil Boiler?
An oil boiler is a heating system that uses oil to provide heating in homes and is a popular choice in areas that have limited access to natural gas.
While furnaces deliver heat through warm air via ductwork, boilers heat water.
This hot water circulates through radiators, baseboard heaters, and other types of heating systems. It’s also referred to as a hydronic heater or a central heating system.
Oil boilers are used to heat water and provide additional space heating. They come in a variety of sizes, ranging from smaller models suitable for small homes to larger ones for extensive properties.
How An Oil Boiler Works
A boiler is a closed vessel in which fluid (typically water or steam) is heated. The fluid flows through tubing to the boilers, where it transfers its heat to a liquid called the “reflux.” This hot liquid then goes through tubes back into the boiler, heating it again and starting the process over.
Replacing An Oil Boiler With An Air Source Heat Pump
It can be possible for an existing oil-based heating system, such as boiler or furnace, to be replaced by an air source heat pump system.
The complexity of the installation, the work required, and the costs involved can be dictated by a number of factors such as:
- The size of property
- The area that needs to be heated
- Whether any indoor apparatus such as radiators and pipes need to be upgraded to work effectively alongside the new heat pump
- Insulation levels
- The requirement for any other features, such as a hot water tank to provide domestic hot water
Any oil tank from the existing heating system will need to be decommissioned and removed if necessary.
The external unit of an air source heat pump system will need to be installed outside in a suitable location.
The size and power output of a heat pump will be determined by the area that needs to be heated, among other factors.
Our own ASHP (air source heat pump) is sized suitably for our 5-bedroom house.
Any indoor heating equipment, such as radiators and pipes, that isn’t sufficient for use with an air source heat pump may need to be upgraded.
Furthermore, if an air source heat pump is also to be used to provide domestic hot water, then any existing hot water tank may need to be replaced with a new one.
For this case study here of replacing an oil boiler with a heat pump, the old oil boiler was decommissioned and was replaced with an external heat pump unit, new radiators and a new hot water tank. The whole installation process took three working days, and other works to the home included increasing insulation levels and installing underfloor heating.
Benefits Of Replacing An Oil Boiler With An Air Source Heat Pump
Can Be Cheaper Long-Term And More Environmentally Friendly
An air source heat pump can be cheaper and more environmentally friendly in the long haul than an oil boiler.
Oil boilers can have higher carbon emissions than other heating systems. They can also require more maintenance, making them more expensive than air source heat pumps in the long run.
However, the same can’t be said for short term costs because an air source heat pump can require a higher initial investment.
As such, switching to this type of heating system can make more financial sense if you plan to stay in your house for at least 15-20 years and are willing to invest in a long-term financial commitment that’ll help save you money over time.
High Seasonal Coefficient of Performance
An air source heat pump’s high seasonal coefficient of performance (COP) is precisely why it can be better than an oil boiler in winter.
Air source heat pumps can have a COP of 2 or more, depending on factors such as outdoor air temperatures and the efficiency of the heat pump, and means that they can generate multiple times more heat energy than the electrical energy consumed.
For example, our own ASHP can have a COP of up to over 4 under the right conditions.
See our articles on air source heat pump COP and air source heat pump efficiency for more information.
On the other hand, other heating systems such as oil can be less than 100% efficient because they use combination to generate heat and lose energy in the process.
Longer Lifespan
Air source heat pumps may also have a longer lifespan than an oiler boiler.
They can typically survive for an extended period of time without the user having to worry about repairs, maintenance, or finding a replacement. If you value longevity and sustainability in a heating system, an air source heat pump can be the way to go.
Drawbacks of Replacing an Oil Boiler With an Air Source Heat Pump
Lower Temperatures
Air source heat pumps are very efficient when it comes to heating. However, they don’t provide as much heat as a traditional boiler.
To overcome this, air source heat pumps should be paired with large surface area indoor heating equipment such as radiators or underfloor heating.
They may also need to run for longer periods of time to achieve the same desired indoor temperatures, but the upside of this is that temperatures can be more constant rather than a burst of intense heating from boiler.
Sufficient Insulation Required
The energy savings of an air source heat pump can be well worth the initial costs for installation. However, you’ll get no reward if your home isn’t adequately insulated beforehand.
Before switching to an ASHP system, consider the level of insulation your home currently has and you may need to factor in the cost of installing additional insulation.
A poorly insulated house may not keep the heat from a heat pump in long enough for indoor temperatures to sufficiently rise.
Can An Air Source Heat Pump Replace An Oil Boiler?
It’s possible to replace an oil boiler with an air source heat pump and an installer will be able to provide details of the upgrades required and the total costs.
An air source heat pump system will work slightly differently compared to an oil boiler system, such as lower output temperatures but providing more constant indoor temperatures through running for longer periods of time.
Sufficient insulation levels and indoor heating equipment will typically be required to make the most out of an air source heat pump, and existing radiators, home insulation and hot water tanks may need to be upgraded.
Further Reading
Parts Of An Air Source Heat Pump Explained
How An Air Source Heat Pumps Works
How Much An Air Source Heat Pump Costs To Buy, Install & Run