Heat pumps are expected to be the future of environmentally friendly home heating in the United Kingdom. They’re fantastic in theory. But aren’t they defective in practise? Potentially. Let’s have a look.
Over 17 million houses in the UK use gas boilers for heating, resulting in hundreds of tonnes of carbon emissions each year, a substantial contributor to climate change.
Domestic heating now accounts for roughly 14% of total emissions in the UK, putting it in direct conflict with the government’s legal requirement to achieve carbon neutrality by 2050.
Low-carbon options such as hydrogen boilers and heat pumps provide a feasible answer to this challenge, giving houses with a more environmentally friendly, dependable, and convenient heating choice.
What is a Heat Pump and How Does It Work?
According to the Committee on Climate Change, 19 million heat pumps will be required to fulfil the goal of net-zero energy by 2050. As a result, they will play a significant role in the UK’s decarbonization of heating.
Heat pumps, as its name suggests, transfer heat from one point to another. They do it by taking heat from the air outside your house or from the ground and using it to heat it.
Heat pumps are divided into three categories:
- Heat pumps using an air source
- Pumps that extract heat from the ground
- Heat pumps with a hybrid design
They collect heat from the air, the ground, or the water and may offer both central heating and hot water, while hybrid heat pumps can supplement heat with a boiler when the weather is really cold.
Heat pumps need very little power to run, and when paired with the fact that they absorb a lot of heat from the environment, they are very efficient.
Unfortunately, air source heat pumps are unable to produce the same steady heat output as gas boilers, making them unsuitable for a wide range of applications. For example, they are often used in conjunction with an underfloor heating system and in contemporary, well-insulated energy-efficient homes.
When a heat pump alone isn’t enough to fulfil your heating needs, consider a hybrid solution that works in tandem with a standard gas boiler.
In our heat pump vs. gas boilers article, we compare hydrogen boilers to heat pumps.
Heat Pumps of Various Types
In the United Kingdom, there are three main kinds of heat pumps, all of which function on the same concept of transporting heat by evaporation and condensation.
Let’s take a deeper look at how each of them works and what they’re used for….
Heat Pumps using an Air Source (ASHP)
Because of its ease of installation and lack of space requirements, air source heat pumps are considered the most probable choice for the majority of residential houses in the UK. They also completely match with the carbon neutral aims since they are entirely electric.
They need a free exterior wall to house the unit, where the absorbed heat is delivered into the residence through a fan.
What are air source heat pumps and how do they work?
Air Source Heat Pumps use the same condensation and evaporation principles as a refrigerator to capture heat from your home’s outside air.
This essentially implies that they reverse the regular condition of thermal energy by taking heat from a cold area and releasing it to a warmer one, transferring it in the opposite direction of typical heat flow.
Air source heat pumps are classified as either air-to-water or air-to-air systems:
Air-to-water systems heat the water in your wet central heating system using radiators, underfloor heating, and hot water storage cylinders, for example.
Air-to-air (A2A) systems are a kind of HVAC system that heat the property using fans that can also chill it, similar to air conditioning, which is perfect for the summer months. As a result, heat pumps are often referred to as reverse-cycle air conditioners.
Pumps that extract heat from the ground (GSHP)
Ground source heat pumps, as the name implies, draw air from the ground rather than from the air.
Because the earth maintains a constant temperature, it may supply much more steady heat than the air, which can be somewhat erratic. This is one of the most significant benefits of GSHP.
GSHPs, on the other hand, are far more complicated to install, requiring enormous areas of land. The installation procedure may also be very inconvenient, labor-intensive, and costly.
What are ground source heat pumps and how do they work?
The ground around the home must be trenched, and a network of pipes holding refrigerant must be installed; this liquid absorbs the heat and maintains a constant temperature of 10°C to 15°C.
The refrigerant is heated and then sent to a heat exchanger within the building, where it is utilised to create heating water and hot water on demand.
Heat Pumps with a Hybrid Component (HHP)
In a seasonal country like the UK, where temperatures may vary by 20°C in a single day, hybrid heat pumps are viewed as a more realistic alternative.
They are often seen to be a better alternative for older houses that are poorly insulated and/or have inefficient heating and cooling systems. In these households, a totally electric heat pump is more likely to fail to supply heating needs consistently throughout the year.
A hybrid heat pump is essentially a combination of an air-source heat pump, which is an exterior wall-hung machine, and a standard gas combi boiler in terms of installation.
What are hybrid heat pumps and how do they work?
A heat pump that operates in tandem with a typical gas boiler makes up a hybrid heat pump system.
The bulk of the heat pumps in these systems will run at 40 degrees Celsius, which will supply enough heat for the most of the year. The heat pump runs around 85% of the time and switches to the gas boiler when the outside temperature drops below freezing and the heat pump is unable to supply the heating needs.
Hybrid heat pumps are not prioritised above full electrification systems, particularly for off-grid residences where installing the requisite gas infrastructure would be prohibitively costly.
This is particularly true for newer, well-insulated homes, where standard heat pumps should be sufficient to avoid the need for a hybrid system.
What sort of heat pump is right for you?
The optimal kind of heat pump for your house is determined by a number of criteria, including:
- Your financial situation
- Your home’s dimensions
- The land on which your house is situated
- The thermal efficiency of your house, or how effectively it is insulated.
Because the ambient temperature of the earth is constant, a ground source heat pump is the greatest option for producing a continuous amount of heat. It is, however, costly and needs sufficient acreage for installation, but if you have the funds and the land, it may be the better option.
A conventional air-source heat pump will suffice for the majority of people in the UK, as long as they have a free exterior wall to place it on.
A hybrid heat pump, on the other hand, may be the best alternative if your home is poorly insulated or has a low thermal efficiency for other reasons, such as structural issues.
The Benefits of Heat Pumps
The following are some of the most significant benefits of installing a heat pump in your home:
A low-carbon option
The device itself utilises solely electricity and does not consume any fossil fuels. Given that renewables account for about 40% of power production in the UK, they are unquestionably better for the environment than gas heaters.
This is anticipated to improve more over time, given the government’s legal commitment to achieve carbon neutrality by 2050.
Low-maintenance appliances and a safer environment
In comparison to a regular gas boiler, a heat pump often needs less maintenance, service, and repairs. In contrast, there are few safety issues, and since they don’t utilise gas, there are less dangers involved with their usage.
Heat pumps have an average efficiency of 300 percent, whereas gas boilers have an average efficiency of roughly 90 percent.
Cools and heats the room
A heat pump, like an air conditioner, may function in reverse, which means it can remove heat from your house when it’s hot.
Heat Pumps Have Drawbacks
Heat pumps, like most things, aren’t perfect, and there are several drawbacks to using them:
There are significant upfront fees
The initial installation expenses for a ground source heat pump or a combination, such as an air source heat pump plus a gas boiler, may be exceedingly costly.
In reality, the Committee on Climate Change (CCC) estimates that switching each UK house to a low-carbon heating system would cost an average of £26,000.
Operating expenses might be rather significant
The operating expenses may be exceedingly costly if utilised poorly or in a house with exceptionally low thermal efficiency, particularly when compared to gas. In any event, the cost of electricity is now significantly greater than the cost of gas, implying that it has a very high operating economy. For example, electricity costs 3-16p per kWh against 3-4p per kWh for gas.
Other improvements are often required
Heat pumps often need the installation of a heat pump compatible hot water storage tank, as well as additional modifications such as new, bigger radiators and house insulation. These additions may increase the price even further.