What Are Heat Pumps?

Renewable Energy Types

In 2019, the UK Government revealed it would end its contribution to global warming by 2050. 

It is the first major economy to pass such laws on the road to net zero. 

Reaching net-zero greenhouse gas (GHG) emissions will need changes across the economy. 

Owners of commercial buildings face more standards and rules to boost carbon reduction. 

One key area to work on is heating and hot water, as they create nearly a third (32%) of the total carbon emissions in the UK. A significant contributor to a building’s carbon footprint. 

Renewable energy is one of the many options available to work toward the new goal, such as- 

• Wind Farms 
• Solar Farms
• Hydroelectric Power Stations 
• Combined Heat And Power  
• Biomass Plants 
• Heat Pumps

Many are starting to turn to heat pumps as a green energy alternative. They can diminish your overall GHG emissions by up to 80%. 

Heat pumps can heat up to 165°C without emitting direct emissions to provide a comfortable working environment.  

The Energy Savings Trust estimate that a ground source heat pump could save around £3,000 per annum. 

The UK government also offers incentives to support businesses switching to sustainable heat generation, such as the Industrial Energy Transformation Fund.

You can see why they are becoming a popular, cost-effective answer to net-zero ambitions.

There are many things to consider when looking to implement on-site, sustainable heat generation. 

Before we go into the various types available, let’s go over the basics.

What Is A Heat Pump?

A heat pump is a standalone device that uses refrigeration technology and electricity to provide heating and cooling.

Most heating systems burn fuel, such as Gas, to create heat. But heat pumps don’t generate heat.

Instead, they move existing heat energy from outside into your building.

Heat pumps provide more heat energy than the electrical power they consume, making them more efficient than other heating methods.

We can also combine with other renewable systems such as solar panels to supply the electricity needed to run the heat pump.

They also do not burn fossil fuels which makes them more environmentally friendly.

However, they are costly to install.

Prices depend on the system, building type and size, but will inevitably be more than a gas boiler.

Heat pumps can significantly save your fuel bills despite the initial cost.

21% of the UK’s carbon emissions are from Gas heating. The government have announced that no new gas boilers will be sold after 2035.

How Do Heat Pumps Work?

Everything around us holds heat that naturally flows from a warmer place to a colder one.

A heat pump pulls the warmth from the ground, air or water, creating hot air and water.

They are able to heat a building more efficiently, while being better for the environment than traditional gas boilers.

But how does it work?

Let’s break down the process into steps:

1. The source of heat (extracted from air, ground or water) is either blown or pumped over the heat exchange surface of the outer part of the heat pump.
2. Although the air extracted is cool, it is warm enough to cause a special refrigerant liquid to evaporate and become a gas.
3. The heat pump uses electricity to squeeze this gas. When the pressure increases, the temperature rises (and vice versa for cooling).
4. The heat passed over the heat exchange surface is delivered around the building via ceiling and wall fans or transferred to a conventional central heating and hot water system.
5. The gas temperature drops as the heat passes through the exchanger, which returns it to a liquid state.
6. The refrigerant is cold enough to absorb more heat from outside and begin the process again until sufficient heat is passed into the building.

Benefit Of Having A Heat Pump?

Many financial and environmental benefits are associated with heat pump installations, which is why they have become very popular over the last decade.

Let us go over some of the significant benefits:

Lower Running Costs

They cost less to run than combustion-based systems. 

The more energy-efficient the systems are, the more significant long-term energy savings. 

Less Maintenance

They require very little maintenance. A once-a-year check is all it needs but will require a professional to check every three or five years.

Superior efficiency 

The average heat pump has an efficiency rating of 300%, while gas boilers have an average efficiency rating of around 90%.

Reduces Carbon Emissions

They have an efficient conversion rate of energy to heat while reducing your carbon emissions, as it burns no fossil fuels. 

Considering that around 40% of electricity generation in the UK is produced via renewables, it’s better for the environment than gas boilers.

And with the government’s legal obligation to reach carbon neutrality by 2050, this is likely to improve further.

Produces Warm & Cold Air

They can operate as both cooling and heating, saving you from needing two different units.

A heat pump is a suitable choice for an all-in-one HVAC system.

Long Life-Span

The working life of a heat pump varies depending on the model you have installed. They range from 15 to 20 years, much higher than a traditional combustion unit.

8 Years	The average lifespan of a boiler
15 Years	The average lifespan of an Air Source Heat Pump
20 years	The average lifespan of a Ground Source Heat Pump

Health Advantages

They improve air quality by filtering the air and dehumidifying your environment. 

Good indoor air quality is essential because it can help prevent sickness and health complications.

Eligible for RHI Scheme

The government provides two types of programs to install renewable heat systems, The Domestic Renewable Heat Incentive (Domestic RHI) and the Non-domestic Renewable Heat Incentive (Non-Domestic RHI).

The Domestic RHI scheme addresses homeowners, social and private landlords, and self-builders. 

Non-Domestic RHI is available to the public sector.

The Downside Of Heat Pumps

Heat pumps have many benefits, but it doesn’t come without their list of cons.

Listed below are some drawbacks to consider.

High Upfront Cost

They will have a considerable upfront cost that can be overlooked when looking at operating costs, long-term savings, and reduced carbon emissions.

Difficult to Install

Air source heat pumps are straightforward, but ground sources are more complex.

If the pipework for your heat pump is installed horizontally, it will be around one to two metres below the surface. 

However, for a horizontal system to be installed, you need around 200 to 400 m2 of land.

If space is restricted, A vertical system is needed, which goes up to 150 metres below the ground.

Research is also required to understand the movement of heat and local geology.

The cost of electricity is currently much higher than gas, meaning it has a high running economy. If misused or in a building with poor thermal efficiency, the running costs can be extremely high, especially in comparison to the gas. For example, electricity costs 3-16p per kWh compared to gas’ 3-4 per kWh.

Questionable Sustainability

Some of the used fluids are of questionable sustainability, which has raised environmental concerns. 

However, you can switch out these fluids and opt to use biodegradable fluids.

Not Efficient When The Temperatures Drop

When temperatures fall to freezing outside, they can struggle to provide the heat source needed.  

Using a backup heating system to take over the heat pump in extreme conditions is possible but can raise your utility bills.

Moreover, at low temperatures, heat pumps can go into defrost mode quite often. The auxiliary heat takes centre stage during this cycle, reducing the overall efficiency by about 10%.

There are opportunities for an upgraded heat pump system to fix these issues. However, they cost significantly more.

Always check the Seasonal Performance Factor (SPF) of your unit.

Not Entirely Carbon Neutral

Heat pumps rely on electricity to operate, making it difficult to be entirely carbon neutral. However, they generally have a high Coefficient of Performance (COP), which means they’re more efficient as the outside air gets cooler.

Planning Permissions Required

You will need special planning permissions In Wales and Northern Ireland to install a heat pump. 

In England and Scotland, it depends on the area and overall size of your building.

The Efficiency Of A Heat Pump

An essential benefit of a heat pump is the energy-efficient heating procedure.

Ground and air source units can exceed efficiencies of 300% since they transfer heat rather than generate it.

However, holding this efficiency level is vital for heat pumps to be beneficial.

Efficiency is just one way to compare various heating systems.

Measuring Heat Pumps Efficiency

Measuring a heat pump’s efficiency can be done using several different methods.

These methods show how efficiently they can perform in cooling, heating, and overall energy output.

Below, you can find different efficiency terms related to heat pumps.

Coefficient of Performance (CoP)

The Coefficient of Performance (CoP) is one of the most common measurements to rate a heat pump.

It shows how efficiently heat pump systems can heat a building under the best possible conditions.

COP is the heating/cooling output ratio to the energy it takes to run the machine.

Heat pumps have no set CoP as they vary depending on multiple variables, but each will have a datasheet telling you what its measured CoP is.

A high COP over 1.0 means your heat pump performs at a high-efficiency level.

A heat pump is the only heating machine with a COP over 1.0.

In simple terms, the heat pumps can deliver 4 and 5 units of heat for every unit of electricity.

If we compare that to electric heaters, they operate at around 100% efficiency, which is 1 unit of electricity that delivers 1 unit of heat.

Commercial air source heat pumps can be as high as 4, and ground source heat pumps can reach 5.

Seasonal Coefficient of Performance (SCoP)

Heat pumps can experience temperature variations throughout the year due to rising and falling throughout the seasons. 

This means the CoP is not always practical in understanding the cost of running the heat pump.

Seasonal Performance Factor (SPF), or The Seasonal Coefficient of Performance (SCoP), is a year-round and more realistic measurement based on CoP under different conditions and a standardised climate.

It is a ratio between the annual heat energy output and the annual electric energy input. 

The SPF depends on the heat pump’s efficiency, COP, the local climatic conditions, and the integration of the heat pump into the building.

The SPF will give you a better representation of what to expect in terms of operating costs and efficiency than the CoP figure.

Seasonal Energy Efficiency Ratio (SEER)

SEER is the rating used to indicate the unit’s cooling output during a cooling season. 

When estimating the EER, energy experts generally factor in static outdoor and indoor temperatures and 50% relative humidity. 

An energy-efficient heat pump will typically be somewhere between 11 and 14 EER.

With a higher EER, the system’s efficiency is better, lowering your carbon footprint.

The EER rating helps consumers determine the air conditioning ability of a heat pump. The government also sets minimum averages for how well a heat pump should perform air conditioning functions.

Cooling energy is always measured in British thermal units (BTU) and represents the amount of energy needed to raise the temperature. 

To calculate SEER you must take the total cooling provided, BTU, divided by the total amount of electricity used, Watts, over the same period.

The Heating Seasonal Performance Factor 

HSPF is the same efficiency measure as the SEER but in heating mode.

Very low temperatures can cause heat pumps to perform less effectively. 

The HSPF score will show you which heat pumps are your best bet during the most chilly winter days. It will allow you to plan your backup heating solution accordingly. 

Comparing Efficiency To Non-Renewable Sources

For comparison, other kinds of heat generation have the subsequent efficiencies:

• Conventional gas/oil boiler: 70-80% efficiency
• Condensing gas/oil boiler: 90-96% efficiency
• Direct electric heating: 35-45% efficiency (with losses in generation and distribution)

How Long Do Heat Pumps Last?

Heat pumps are typically long-lasting if there are maintained and serviced correctly. 

Older models of heat pumps had an average life expectancy of around 15 years. 

Thanks to several technological evolutions, modern heat pumps last around 20-25 years before they need replacing.

Usually, the first thing to fail is the compressor due to burnout, as the component rarely stands idle. 

A faulty compressor raises the temperature of the refrigerant within the heat pump. 

Depending on the age of the heat pump, it might be more economical to replace the entire system or just the compressor itself.

Different Types of Heat Pumps

Heat Pumps help organisations to lower their carbon emissions and energy spending. 

But how do you choose between air, ground or water? 

Let’s take a look at each:

Air Source Heat Pumps (ASHP)

The most familiar type of heat pump is the air-source heat pump.

The fan-powered unit extracts warmth from the outside air using a small amount of electricity. The extracted air runs through a compressor (also known as a heat exchanger), which raises the temperature. 

The pump needs electricity to operate but uses less than the heat it delivers. Because of this, it reduces the overall carbon emissions.

The amount of heat they can create relies on the size of the unit. Most commercial ASHP can be set up in a cascade configuration to provide on-demand space heating, hot water and active cooling.

Overall, ASHP is up to 300% efficient. A commercial gas boiler typically sits around 90 to 100%.

Advantages and Disadvantages of ASHP 

Advantages

• Currently eligible for government grants (RHI)
• High SCOP
• Space heating and hot water
• Air sources can be used for heating and cooling
• Long lifespan
• Low maintenance and maintenance costs
• Easier installation
• Possible to improve efficiency by using the waste heat
• Potential to incorporate heat storage

Disadvantages

• Efficiency is highly dependent on ambient conditions.
• Reduced thermal energy management
• Low efficiency of the system can impact the business case.
• Most insufficient lifetime carbon savings of all heat pump source options
• ASHP’ can be noisy

Ground Source Heat Pumps

The outside air isn’t the only place to draw valuable heat to warm our houses.

Ground Source heat pumps can utilise the solar energy stored in the ground via heat pipes buried into the earth.

Also called geothermal heat pumps, they use water and antifreeze pumped into the ground.

The constant temperature of the ground continuously warms up the antifreeze mixture.

The fluid feeds into a heat exchanger, and the energy absorbed is transferred to a refrigerant.

The refrigerant boils at a low temperature until it turns into a gas.

The gas is compressed, which raises the temperature.

GSHP have higher efficiencies than air-sourced heat pumps as the temperatures in the ground are generally more constant.

With every kW of electricity the pump uses, around 3-4 kW of heat gets generated.

With that in mind, the GSHP has, on average, a Coefficient of Performance (COP) of 3.5 to 4.5.

The trade-off with greater efficiency is that they are usually more expensive to install. Most of the cost is the excavation work needed to lay the piping.

The piping can be applied in two different ways, Horizontal or Vertical.

Horizontal Ground Source Heat Pump

The most cost-effective way to pull warmth from the ground is through horizontal loops of plastic pipe.

The trenches in which the pipes sit are usually 1 meter deep, around 4 meters apart, and about 100-150 meters long.

Vertical Ground Source Heat Pump

Vertical GSHPs are more costly when there is not enough space to apply the pipes horizontally. 

This is due to the requirement of specialist equipment to create the borehole.

The boreholes must be at least 6m apart and range from 50 to 50 m deep. 

Open And Closed Loops Systems

An open-loop geothermal system pipes clean groundwater directly from a nearby aquifer to an indoor geothermal heat pump.

The water leaves and is expelled through a discharge well located a suitable distance from the first.

Depending on local regulations, the water may be directed into a local pond or approved drainage ditch.

Because open-loop systems utilise water on a “once-through” basis, they are often referred to as “pump and dump” systems.

A closed-loop geothermal method continuously distributes a heat transfer solution through the buried (or submerged if in water) plastic pipes.

These pipes connect to an indoor heat pump which provides heating and cooling.

Closed-loop systems are often cheaper to install because the loop only needs to be filled once. However, open-loop systems can achieve greater efficiencies.

Advantages and Disadvantages of GSHP 

Advantages

• Significantly increased seasonal performance over air-source
• A more significant reduction in associated carbon emissions
• The ground loop system enables seasonal thermal balancing.
• GSHPs require less maintenance than combustion-based heating systems.
• Low carbon emissions (no carbon emissions at all, if a renewable source of electricity is used to power them).

Disadvantages

• The process of drilling boreholes can be disruptive
• High installation costs
• More challenging to retrofit on a current site

Water Source Heat Pump (WSHP)

Water source heat pumps have been around since the late 1940s. 

They are often considered more efficient because heat transfers better in water.

Temperatures in water are generally more stable throughout the year. Therefore, water source heat pumps can reach reasonably high efficiencies of 300% to 600%. Air sources hit around 175% to 250% on cool days.

A WSHP can take two kilowatts of free heat from the water and one kilowatt of electricity to produce three kilowatts of heat. 

It uses a series of submerged pipes which contains a special fluid to absorb the heat from a river, lake, large pond or borehole. 

Advantages and Disadvantages of WSHP 

Advantages

• Seasonal performance can be better than ground-source
• A larger reduction in carbon emissions
• Works well with other heating systems
• Retrofitted
• Can use the water source to supply ‘free cooling.’

Disadvantages

• Must be near a sustainable source of water
• Special planning permissions needed

Heat Pump Maintenance

Commercial Heat pumps are reliable and require minimum maintenance, offering maximum peace of mind.

A well-installed, good-quality ground or air source heat pump will typically come with 25 years’ worth of performance, with no loss of efficiency.

Compared to the average boiler, they can lose up to 2% efficiency per year, with a life span of 12 years [Which? 2015]).

Your supplier/installer should provide details about your heat pump’s exact maintenance requirements and how it can be optimised.

As a general rule of thumb, to ensure proper functionality, you should have your installation checked annually by a qualified engineer.

Most ground and air source heat pumps come with a standard five to ten-year warranty on labour and parts.

Air Source Heat Pump Maintenance

Air Source Heat Pumps don’t need much ongoing maintenance. 

While each ASHP is different, there aren’t many maintenance differences. 

Manufacturers still advise owners about what their systems require regarding seasonal or annual maintenance.

Some maintenance tasks you can perform yourself to ensure that your system operates as intended:

• Clean fans and foils (if need be)
• Swap out or clean filters
• Clean the system’s supply
• Un-block Airflow debris (dust, leaves, etc.)
• Check and clean the fan blades

Before winter or summer, if you use your heat pump for cooling, it’s recommended to have it serviced by an expert. 

A qualified expert conducts a more comprehensive audit of the system’s components. The engineers can better pinpoint issues that could degrade a heat pump’s performance that users wouldn’t spot or diagnose.

These checks involve the following:

• Checking refrigerant pressure and levels
• Reviewing ducts and correcting them if required
• Measuring airflow
• Inspecting ducts, coils, filters and blowers for any debris that could impede airflow
• Checking for system leaks
• Examining electrical connections
• Lubricating motors
• Checking reverse cooling/heating controls and ensuring they’re operating as required
• Studying and testing thermostats under normal operating conditions

Unlike other types of renewable energy technologies, air source heat pumps generally don’t require the replacement of costly parts during their lifespan.

Ground Source Heat Pump Maintenance

Although ground source heat pumps require little maintenance, they still need yearly checkups by a professional. This is to ensure that they function within their tolerances.

Large commercial pumps are subject to stricter maintenance requirements.

Most GSHP will last for more than 25 years, with most continuing to operate without a hitch well beyond this period.

Although, an underperforming heat pump could lose up to 25 per cent of its efficiency in operating energy consumption.

If a ground source system’s thermostat is set very low, it can cause the system to use the costly auxiliary heater.

As a result, the unit will use more than the usual energy to operate.

The manufacturers will specify a unit’s recommended service and maintenance schedules in their documentation.

Here is an overview of the primary parts that need checking:

• The compressor – if it fails, the entire thing will have to be replaced as it’s a sealed unit
• The control equipment and electronics
• Above-ground pipes and connectors
• The water pump – which is the only movable part of the system
• The bleed system, radiators, and system fluid
• Coolant/antifreeze fluid in the ground array – it is advisable that you check if the chemical mixture is correct

It is worth noting that “F” gas certified engineers can only work on devices designed to contain or contain F-Gas refrigerants. 

Since ground source heat pumps have very few components making up the system, it is currently one of the most efficient heating methods.

Common FAQ’s

Varlowe’s Commercial Heating Service

Varlowe provides a nationwide Commercial Heating Service Based out of our head office in the West Midands.

Our commercial gas engineers can provide renewable heating solutions to help you reduce your carbon footprint and energy bills. They have the expertise to ensure you receive the highest service standards.

For more information, please visit our Commercial Heating Services page, or call us on 01902 861042.

We also have a blog post “Different types of commercial heating systems” if you want more information on heating types.