How to get your home ready for a heat pump

Heat pumps operate and cost less to run in well insulated homes. For some people, this might mean they need to make upgrades to their property. In this article, we look at what this involves.

Why do heat pumps require home modifications?

To understand why you may need to make changes to your home, it is useful to learn a little bit about how pumps work – and how they’re different to traditional boiler systems.

When a home is heated by a boiler, it burns gas (or other fuels) to quickly warm water. The water is pumped through to the radiators, usually at a high flow temperature (around 60-75°C). Therefore, people tend to run gas boilers in short bursts.

With a heat pump, water is usually heated to a lower temperature of around 35-45°C (which still feels very warm – like a hot bath) to maximise its efficiency. This means the radiators are ‘cooler’ to touch, while still being warm. For this reason, you’ll usually leave them running for longer periods to keep the home warm in a more comfortable way.

At lower temperatures, smaller radiators wouldn’t emit as much heat as they would if you used a boiler operating at a higher temperature. So, for heat pump systems, it is recommended that radiators are sized appropriately for the design flow temperature, which in some rooms may mean a larger surface area is required.

Heat pumps are also far more cost-effective in insulated homes. They can still heat a poorly insulated and draughty building, but the heat pump would have to be larger, therefore costing more to buy, and it would require more energy to heat the home, therefore costing more to run.

Who needs to upgrade their home when getting a heat pump?

Not everyone will need to make significant changes to their property when getting a heat pump. As a rule of thumb, the newer the building, the fewer the changes – if any – that you’ll need to make.

  • Homes built since the 1990s should have sufficient insulation throughout, double glazing, and may even have features like underfloor heating.
  • Homes built between the late 1970s and the ‘90s typically have lower levels of loft insulation as standard and single glazing.
  • Homes built from the 1930s to the ‘70s typically have cavity walls, single glazing and minimal loft insulation.
  • Homes built before the 1930s typically have solid walls, single glazing and no loft insulation.

Of course, many homeowners have already taken steps to reduce the heat loss of their property, such as upgrading to double glazing, fitting cavity wall insulation or increasing the loft insulation. If you or a previous owner have already upgraded the home, then there will be less work to do.

How to get your home ready for a heat pump

Depending on the age and current set-up of your home, the extent of the changes you need to make to get heat pump-ready will vary. Here are the main things that most homeowners will have to consider.

Insulation

According to Ideal Home magazine, about a quarter of an uninsulated home’s heat escapes through the roof, between 35% and 45% goes through the walls, and 10% is lost through the floor. By insulating the building, you’ll ensure that your heat pump doesn’t have to work as hard to replace that lost heat.

  • Loft insulation: Insulating your loft is a quick and easy way of trapping in heat. As noted above, most homes built since the 1990s should already have a good level of loft insulation. For older buildings, laying insulation is often very quick and easy.
    If you’re happy doing DIY, insulation material is inexpensive, and it is fairly straightforward to lay out yourself. The Energy Saving Trust has more information on loft insulation.
  • Cavity wall insulation: Almost all homes built since the 1930s have cavity walls, which is where there is a small air gap between the inside and outside layers of brick. Cavity wall insulation involves filling that space with insulating foam or beads which help with heat retention. You will need a specialist to do this – they will make small holes in the wall and inject the material into the space. The National Insulation Association has a directory of installers.
  • Solid wall insulation: Pre-1930s buildings typically have solid walls. To insulate these walls, special insulation boards can be placed either on the inside walls or the outside walls. These are then painted or plastered over so they look in keeping with the rest of the house.
    Interior wall insulation tends to be cheaper, but you will lose a couple of centimetres of floor space. Exterior wall insulation is more expensive and would require scaffolding when attaching the insulation to higher floors. Again, the National Insulation Association lists experts in this field.

New hot water cylinders

A hot water cylinder stores warm water for showers or for washing the dishes. Some homes may already have a cylinder, but if you get a heat pump, you will likely need a new one.

Radiator upgrades

Because most heat pump systems have a lower flow temperature than traditional boilers, they are most efficient when combined with radiators with a large surface area. Depending on the type and age of existing radiators you may need to replace some of them.

Having a radiator with a larger surface area does not mean you’ll need to give up more of your wall space. Modern double or even triple panel radiators increase surface area to emit heat. They may be deeper than traditional radiators but can be sized to take up less wall space. A qualified installer will do the necessary heat loss and sizing calculations and will be able to advise you.

Heat pumps are also very well suited to underfloor heating systems. Installing underfloor heating is more expensive than wall-mounted radiators, but depending on the level of work you are undertaking, might be worth considering.

Window upgrades

In UK homes, around 18% of heat is lost through windows according to government research, but that proportion almost doubles for single glazing. So, if you have single glazing, it may be worth upgrading your windows to reduce heat losses and reduce energy consumption of your home.

Fix draughts

In 2018, the Energy Saving Trust reported that some 44% of UK homes have draughts. These currents of cool air bring the temperature down in your home and means that you are wasting energy from your heating system which will work harder to maintain the desired temperature.

The good news is that fixing draughts is usually relatively easy with a bit of DIY – fitting foam, metal or plastic strips over gaps around doors can go a long way to preventing many draughts. For more complex draughts (such as gaps in brickwork, or in older buildings), it is best to consult a specialist – the National Insulation Association would be a good starting point.

Financial support for home upgrades

While getting your home ready for a heat pump may require some investment, the good news is that there are a variety of grants available across the UK where the government or your local council will provide money for some – or even all – of the upgrades.

Getting ready for your heat pump

Across the UK, tens of thousands of people have already had heat pumps installed. Although some homes may need upgrades to get the most benefit from their heat pumps, the level and extent of the changes may be less than you might expect. You can also tackle these upgrades one at a time – it does not need to involve one huge upfront layout.

To figure out exactly what upgrades you’ll need to get your home ready for a heat pump, speak with a qualified installer. The Microgeneration Certification Scheme lists certified installers who have the experience and expertise to advise you on exactly what changes your property will need.