Although heat pumps are still considered a relatively new form of heating, early adopters of air source heat pumps may now find themselves in the position of needing to upgrade it. Or, perhaps you are simply wondering what's involved when you need to upgrade yours in the future.
Most homeowners are fully aware that gas and oil boilers do not last forever and that from time to time it is inevitable that the boiler will need to be replaced. It's the same with heat pumps, but at the same time as replacing or upgrading the unit, you may also need to make additional changes.
From the cost implications to dealing with regulatory issues, heating expert, David Hilton, explains just what's involved when you upgrade a heat pump
What are the costs involved with upgrading a heat pump?
Unlike new heat pump costs, a replacement heat pump is not usually eligible for the Boiler Upgrade Scheme payment. Both the heat pump and installation costs will need to be covered by the homeowner, and as such some homeowners do opt to go back to a boiler system due to the cost involved.
That said, if (and it is a big if) the original heat pump was correctly designed and installed well then there should be very little that needs changing in the system, other than the heat pump unit itself and a small amount of wiring to connect the controls. The cost should therefore be a lot less than an initial heat pump installation.
However, if the original heat pump system was not installed correctly, the emitters (radiators and underfloor heating) were not sized, specified and installed correctly, and the pipework is not large enough, then the costs could be very much in line with the cost of an initial installation and conversion, which may not be a viable solution.
Planning and building regulations requirements
What you may not realise, is that just because you have already got a heat pump it does not mean you can automatically replace it, even if it seems to be like for like.
Heat pumps in many cases get get installed under Permitted Development Rights (PDR), meaning that if you tick all of the conditions required for installation then you do not need to apply for full planning permission.
However, this also means that if your original heat pump was installed under PDR, then any replacement heat pump must comply with up to date permitted development details.
The notable issue here relates to the sound assessment requirements. Sound assessments look at the proximity of an air source heat pump to the 'assessment position'. This is defined as one metre outside the centre of a window of a habitable room on a neighbouring property.
The sound assessment methodology changed in May 2025 which will mean it will have to be recalculated when you upgrade to a new heat pump. This could subsequently affect the outcome of an upgrade meeting PDR.
If any physical changes have taken place during the time that the heat pump has been in situ, then this can also impact the feasibility of replacing the unit. For example, if the neighbours have built an extension, new dwelling or annexe, that is now closer to the heat pump than the previous habitable room was at the time of installation, then that could be a hurdle.
The rules around barriers between the heat pump and the assessment position have also changed so that the fence between the home and the neighbouring property needs to be at least as high, and as robust, as the time when the heat pump was installed, possibly even more so.
All domestic hot water storage systems must also be compliant with Part G of the building regulations. Since 2010 that includes both vented and unvented systems (that’s gravity feed (low pressure) and mains (high pressure) systems to the non-technical reader). Your new heat pump installation must therefore be installed and be certificated by a competent person as compliant with these regulations.
Options when upgrading a heat pump
Heat pumps have certainly evolved in the last 15 years which means there are now more efficient models that are far more intuitive to your home and heating needs. This means if you're upgrading an older model there are improved versions to choose from.
But how does this look in operational terms?
Back in 2010 most heat pumps had a fixed speed compressor. This meant that the unit would only produce a fixed amount of heat. The heat pump was either on (at full capacity), or it was off. There was no in-between and the only way to prevent the heat pump stopping and starting in short cycles was to fit a large cylinder to the central heating system to store energy.
Modulating compressors (also known as inverter compressors) were soon introduced and now most, if not all, air source heat pumps have modulating compressors which allow the heat pump to deliver a range of outputs.
The heat pump tries to match the heat load of the home and modulates up and down depending on the demand and therefore does not need a large cylinder, often needing no cylinder at all.
The refrigerants have also changed over the years to comply with Global Warming Potential (GWP) rules. The latest refrigerants, such as R290 (which is actually refrigerant quality Propane) can achieve higher temperatures than most of the previous refrigerants that were used in domestic heat pumps.
Higher temperatures are less efficient than lower temperatures in a heat pump, but because the heat pump modulates it will only operate at higher temperatures when the demand requires it. So in other words, the colder the air temperature is outside, the warmer the heat pump flow temperature will be.
Many heat pumps also now have a full online monitoring capability. The manufacturer or the installer can remotely access the operating data from the heat pump and in the event of an error, or breakdown, the data can often provide a diagnosis of the issue which may negate the need for a visit from an engineer, but also allows the engineer to come prepared if the visit is required.
The data can be analysed by the engineer to interpret running patterns and they can make suggestions to optimise the operation of the heat pump. If certain rooms are triggering the heating system then this becomes very important information when readjusting the system for optimised efficiency.
The reality is that installing a replacement heat pump is not as simple as replacing a boiler. Many of the calculations need to be redone, and any regulatory or physical changes must be accounted for. The good news is that the answer to how long does a heat pump last is that you should get between 20 - 25 years of use before it does it need upgrading.
When choosing a new model, make sure you get a few quotes from reputable installers as they will be fully versed with the industry updates, and also should be able to advise you of any work that is required to optimise the heat pump as part of the quoting process.
Heat pumps work ‘low and slow’ and boilers work ‘hard and fast’ so the system must always be designed and operated with this in mind. More advanced heat pumps should be easier to optimise and monitor for maximum efficiency, making the decision to upgrade your heat pump one that will reap rewards in the long run.
