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Return home1.5. Heat pump myths
In this section we look at popular misconceptions about heat pumps from both a consumer and installer perspective.
Heat pump myths
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A heat pump system can be designed for lots of types of homes, even those without much space. There are three main types of heat pumps, all with slightly different space requirements.
An air source heat pump requires a small amount of outside space, positioned somewhere where air is flowing.
A ground source heat pump requires a space accessible to digging machinery as underground pipes need to be installed. Once installed, the trenches are filled, and the space is returned to its previous use. People with smaller gardens can bury the pipes into drilled boreholes (which may be 100-150m deep).
A water source heat pump requires access to a body of water, and its pipes are submerged underwater.
Indoors, the home will require space for a hot water cylinder if you don’t already have one.
Each heat pump type has different indoor space requirements.
The air source monobloc system needs a compressor and controls. An air-to-air system needs an internal air circulation system. An air source split system, ground source, and water source heat pump all require space for a compressor and controls. An internal unit is also needed and is often smaller than a standard boiler.
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Underfloor heating isn’t essential but installing it can help improve the efficiency of the heat pump.
A heat pump operates most efficiently when delivering lower temperature water than a traditional boiler would (up to 45°C). A larger radiator can operate at a lower temperature and provide as much heat into the room as a smaller unit, however it won’t be as warm to touch.
The larger the radiator surface area, the lower the water temperature required to provide the same amount of heat into the room.
If the home has underfloor heating, the whole floor is emitting heat into the room. The heat pump can run at an even lower temperature because underfloor heating offers a more extensive surface area than large radiators.
However, neither underfloor heating nor oversized radiators are essential. A heat pump system can be designed to work with smaller radiators by using a high temperature heat pump.
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Hot water requirements need to be considered when designing a heat pump system.
Many heat pumps can provide hot water over 60°C consistently (the minimum temperature the hot water cylinder will need to reach to kill harmful bacteria).
However, it’s often more cost-effective to run the heat pump at this temperature periodically and this is called a sterilisation cycle. An electric immersion heater (or even solar hot water heating) in the hot water cylinder can top up the water temperature when needed. For instance, most heat pumps will heat hot water to 50-55°C very efficiently then the sterilisation cycle raises the temperature to 60°C and holds it there for a certain period.
High volume hot water users may need a different design to low volume hot water users.
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This will depend on the type of heat pump. Air-to-water heat pumps (monobloc) will circulate heated water to the outside unit. Consideration will need to be given to the type of pipe used, for ie pre–insulated pipe and the level of insulation. A split system will circulate refrigerated gas which can be easier and more efficient to site further away from the building.
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This will require a detailed site survey to confirm the pipe and sizes. The microbore pipe (8, 10 and 12mm) may need to be replaced with larger diameter pipes (15mm) to allow more heat to flow to the radiators.
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Heat pumps do work nicely during winter, so your customer can heat their house during the coldest of snaps.
One of the key benefits of ground and water source heat pumps is the consistency of temperature. The seasonal performance factors of ground and water heat pumps – an efficiency measurement – is often better than their equivalent air source heat pump.
Ground and water heat pumps are a good option for areas that regularly experience very cold air temperatures.
Underground temperatures are constant year-round (typically around 10-13°C). The earth’s geothermal warmth provides a ground source heat pump with all the heat it needs to work, no matter how cold the air temperature outside.
Watercourses such as a river, stream or loch offer similar, stable annual temperatures (7-12°C).
An air source heat pump can still draw heat from the air when temperatures drop as low as -15°C. However, its efficiency will reduce slightly as air temperatures fall.
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Heat pumps do have significant upfront costs, but these can be offset by:
Financial support: For example, the Home Energy Scotland Grant and Loan offers Scottish homeowners support to help with heat pump installation costs and the Scottish Government’s SME loan scheme offers Scottish businesses support to help with heat pump installation costs.
Reduced energy bills: A heat pump uses electricity so your customer will continue to receive energy bills. But they will save on the fuel they are replacing, especially if they are replacing an electric heating system.
Costs will vary depending on the size of the house or building, ease of access, the number of radiators to be replaced, the type of underfloor insulation to be installed and reinstatement work.
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A heat pump doesn’t need to be on all the time, but the best way to heat a home with a heat pump is different from traditional systems.
Most gas or oil heating boilers run at full output when they first come on, producing very hot water to heat the home quickly. With a heat pump, it’s better to have the heating come on earlier and run for longer, heating the house slowly and keeping it comfortable. Using the heat pump at lower temperatures for more extended periods prevents the heat pump from stopping and starting and having to produce hot water.
If the householder goes out for a few hours, it won’t be worth turning the heating off as this would mean the heat pump has to operate at a high temperature to heat the home when they get back.
The heating can be automatically controlled by thermostats or zone controls — so your customer doesn’t need to worry about changing their heat pump settings.
Many manufacturers also include wifi-enabled controls so the heat pump can be controlled remotely.
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There are many examples of heat pumps running successfully and cost-effectively in older properties.
The heat pump will have to be designed based on the customer’s heating needs and property type. There are many heat pump models, so select one that best matches their needs. It’s good practice to discuss options to increase insulation and draught-proofing, as well as potentially upgrading radiators to get the most out of the new system.
Sometimes, it might be challenging to install a heat pump in a property for practical or financial reasons. In that case, a hybrid (also known as bivalent) system, which usually involves installing a fossil fuel boiler along with the heat pump, may be an option.
The homeowner should always check with the local planning authority if they require planning permission, especially if they live in a conservation area or listed building.
Always check with the Distribution Network Operator (DNO) to ensure the building electrics can take the increased load.
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Heat pumps are energy efficient and can produce 2.5 – 4 times more heat energy than the electricity needed to run them.
In 2020, renewable energy sources generated 97% of Scotland’s electricity. Heat pumps offer Scotland the chance to warm its homes and business using power from renewable energy rather than burning fossil fuels.
When providing a cost for your customer, MCS requires that an Energy Performance Estimate is also provided. This will allow you to work out financial and carbon savings.
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Once installed, a heat pump requires very little maintenance. They are safer than gas, oil or LPG systems because they don’t use flammable fuels, and there is no risk of carbon monoxide accumulation.
Your customers should always follow the heat pump manufacturer’s recommendations about system maintenance. This may be annually to ensure the warranty remains valid.
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Many heat pump installations may not require planning permission. However, always make sure the homeowner has checked with their local authority if they need planning permission as the heat pump may be permitted development.
People living in conservation areas, national parks, listed buildings or commercial customers have more restrictions.
Water and ground-source open loop systems require a water abstraction license, separate from planning permission. In Scotland, abstraction permission comes from the Scottish Environment Protection Agency (SEPA).
