Engaging homeowners: messaging that drives earlier boiler replacement planning

We are grateful to the MCS Foundation for supporting some of the research and marketing activities in this project.

Summary

Last minute boiler replacements can cause stress and inconvenience for homeowners. More broadly it can also frustrate government plans for the transition to new low carbon electric heating as homeowners are likely to need time to consider their options and make the practical arrangements needed to switch to a new form of heating.

This research sought to identify the messages that are most likely to engage homeowners and encourage them to plan ahead for the replacement of an old heating system. The three message themes that were most effective in engaging homeowners:

1. Messages that reduced immediate barriers such as cost -“Government grants and loans could make upgrading your boiler to a heat pump more affordable”
2. Messages that highlighted tangible risks of delay, like losing heating or hot water - “Planning ahead for your next heating system means you won’t be left without heating or hot water when it matters most”
3. Messages that framed planning as a practical, manageable step -“Planning ahead your boiler replacement means it can be done when convenient to you or alongside other major works”

Our findings suggest that combining the first two messages above - information about financial support and avoiding the disruption of a last minute replacement - was the best way to engage the most homeowners (85%). 

If messages about financial support were excluded, the three messages that achieved the highest homeowner reach combined (73%) were those that highlighted tangible risks of delays, that reframed planning as a practical manageable step, and that included moving on to a heat pump for sustainability reasons. 

These messages worked across most groups of homeowners, with some small exceptions. For example, families are more motivated by messages that highlight the cost and lack of choice a last minute boiler breakdown can incur. 

Which? is calling on governments and companies to: 

• Support initiatives that enable targeted engagement with homeowners at key decision points, for example homeowners with older boilers who are approaching the point where they will need to replace their boiler. 
• Use regular communications to encourage early planning for boiler replacement, helping homeowners avoid last-minute distress purchases and creating a natural opportunity to consider electric heating. 
• Focus messaging on what matters most to homeowners. Our research suggests that affordability, reduced disruption, and convenience, are the themes that are most likely to drive engagement.
• Provide accessible information and advice to support decision making. Linking to independent sources of advice can increase consumer confidence and support informed decisions.

Introduction

Although home heating can be a hot topic in the winter months, generally homeowners don’t give much thought to the boilers that heat their homes - until they stop working. 

Which? research found that three in four homeowners with older boilers (over eight years old) had no plans for replacing their boiler. Six in 10 (60%) told us they service their older system annually, which may reassure them that any issues will be addressed. However even amongst those homeowners whose boilers were showing signs of wear and tear more than half (53%) had not made any plans for its replacement. A quarter (27%) say they will just ‘wait and see.’

In many ways this suits busy homeowners who already have enough to think about. However, not planning ahead doubles the risk of an emergency replacement, which in turn reduces the chance the homeowner can organise the replacement at a time to suit them, or choose the installer, or the type of system they want. Emergency purchases also tend to create more disruption, time without heating and hot water, and negative emotional and practical impacts.

Our research also shows that planning ahead can have benefits for homeowners. Installers told us that fixing a problem early can prolong the life of a boiler and talking to an installer before a boiler stops working enables homeowners to consider making changes to their new system that will make it more efficient in the long run. 

More broadly, last minute boiler replacements are also frustrating government plans for the transition to low carbon electrified heating, as homeowners do not have the time to research their options and make arrangements for switching to a new electric system.

A new context

Over the next ten to twenty years, the UK government is encouraging all households to consider switching from gas and oil boilers to new electrified heating systems such as a heat pump. This is part of the Warm Homes Plan, a national programme to cut energy bills, improve energy security and cut carbon emissions.

In 2024 approx 60,000 heat pumps were installed across the UK. Whilst this represents an increase on the previous year, the UK still has a mountain to climb to meet the targets set by the Climate Change Committee (CCC) in support of the 2050 net zero commitment. This would require the installation rate to rise to 450,000 per year by 2030, and by 2040 half of all existing homes must be equipped with a heat pump.

In order to encourage more households to consider switching the government has launched a campaign to raise awareness about heat pumps, and introduced the Boiler Upgrade Scheme (BUS) grant to help households with the upfront cost of installing one. It has also started to cut electricity prices to reduce energy bills for households that switch. Our research suggests that government policy and growing awareness is having a positive impact on the number of homeowners open to considering a heat pump. The number of heat pumps being installed is also increasing, though not at the rate required to meet the target set by the CCC. 

Central to the UK’s ability to meet the target set by the CCC is the expectation that homeowners will switch to heat pumps as and when their old systems need replacing. This will be more efficient as there is no need to rip out working boilers and it will provide for a gradual transition from gas and oil to electric. However this approach sits uncomfortably with homeowners' current behaviours around replacing their boilers. For most homeowners a heat pump is a relatively new technology for home heating and they need more time to consider their options. They will also need to address practical issues such as getting a heat loss survey, understanding any additional changes that may be needed in the home and identifying an installer. This means that a homeowner who is making a last minute decision because their boiler has already stopped working is very unlikely to switch to a new electric system.

Purpose of the research

In order to encourage consumers to plan ahead for the replacement of an old heating system the government and businesses need to nudge consumers towards a new behaviour. This can also be an opportunity to provide the information and advice that consumers need to make an informed decision about their next heating system. This research aimed to find out whether that was possible and which messages were likely to be most effective. 

Methodology

We conducted an online survey with 1,190 homeowners in the UK who had responsibility for their heating systems. The research was conducted between 24th to 26th October 2025. 

Using a MaxDiff (maximum difference scaling) exercise, respondents were asked to evaluate eight different message themes, selecting the most and least compelling message that would encourage them to plan ahead for their next heating system. This method allowed us to rank the different messages according to their relative appeal among homeowners. 

In addition, a TURF (total unduplicated reach and frequency) analysis was conducted to identify the combination of messages that would reach the largest proportion of homeowners.

To understand which message themes resonated the most with homeowners, we developed eight message themes using the insights from our previous research, alongside evidence on the slow uptake of heat pumps to date (see Figure 1). 

Figure 1: Table of Message Themes (MT)

The most compelling messages were about financial support and planning ahead to avoid disruptions

Our research found that homeowners ranked heat pump financial support as the most compelling message that would encourage them to plan ahead for future boiler upgrades. This was followed by planning ahead to avoid disruption (loss of heating and hot water), which ranked second, and planning ahead alongside home improvements which ranked third (see Figure 2). We found that messages that focused primarily on future-proofing, guidance, or sustainability were less compelling overall.

Figure 2: The most compelling messages for encouraging future planning and boiler upgrades (share of preference out of 100%)

The strongest performer by some distance was MT2 Heat pump upgrade - financial support with 24% of homeowners preferring this message theme the most:

“Government grants and loans could make upgrading your boiler to a heat pump more affordable”

This suggests that affordability does play a central role in heating decisions and, while we know from the limited uptake in heat pumps, that money alone may not trigger early action, it may continue to be a powerful hook for capturing attention and encouraging homeowners to plan to upgrade their boiler.  

The second most compelling theme was MT7 Planning ahead to avoid disruption (e.g. losing heating and hot water if your boiler breaks down), with 15% of homeowners preferring this message theme:  

“Planning ahead for your next heating system means you won’t be left without heating or hot water when it matters most”

This suggests that homeowners are highly motivated by the prospect of avoiding disruption at critical moments. It may reflect the lived experience of boiler breakdowns, which according to our previous research is often stressful and difficult to manage, particularly in the colder months. 

The third highly ranked message theme was MT1 Planning ahead with home improvements with 13% of homeowners saying this was compelling: 

“Planning ahead your boiler replacement means it can be done when convenient to you or alongside other major works”

This theme framed boiler upgrades as something that can be done at a time that suits the household, or alongside other major works. Its strong performance suggests that presenting early planning as a way to maintain control and convenience for homeowners (rather than reacting in a crisis) can help shift attitudes towards more proactive behaviour. 

In summary, the most effective messages are those that:

1. Reduce immediate barriers, such as cost.
2. Highlight tangible risks of delay, like losing heating or hot water.
3. Reframe planning as a practical, manageable step.

Combining financial support with avoiding disruption messages drives the widest reach 

A TURF (total unduplicated reach and frequency) analysis was conducted to identify the combination of messages that would reach the largest population of homeowners. 

The MT2 heat pump financial support message alone would appeal to around 71% of homeowners. When combined with the MT7 Planning ahead to avoid disruption message, which highlighted the risk of losing heating or hot water if a boiler breaks down, had a potential engagement rise to reach 85% of homeowners (see Figure 3).

Figure 3: Impact of combined message themes using Total Unduplicated Reach and Frequency (TURF) - all messages (%)

After combining the two strongest messages - MT2 Heat pump financial support and MT7 Planning ahead to avoid disruption from boiler breakdown - adding further message themes delivers only small additional gains. 

The third largest increase comes from adding MT6 Help & advice to upgrade, which adds another 4% to the reach (88%). Other messages only add small incremental reaches and are not as impactful.

The TURF analysis shows that a small number of well-chosen messages could engage the vast majority of homeowners, while adding more messages beyond these few provides limited extra effect. 

Two messages resonate widely, but the third depends on the audience

We examined how reach changed across different groups of homeowners. In every subgroup, the same two messages - MT2 Heat pump financial support and MT7 Planning ahead to avoid disruption - delivered the strongest reach, engaging between 78% and 89% of each group. 

However, the third message that extended reach varied depending on the subgroup. MT6 Help & advice to update was most common, followed by MT1 Home improvement planning. This worked for all subgroups except young adults (homeowners aged 18-34) and families (those with children at home) who were more likely to be influenced if the third combined message was about MT5 Planning ahead to avoid costs and limited options (see Figure 4):

“Waiting to replace your boiler until it has broken down could mean rushing big decisions, higher cost and more limited options. Better to prepare now”

The other subgroup that had an exception were homeowners who were undecided about whether to get a heat pump. For these people, the third message that was most effective at reaching these people (alongside the other two messages) was MT8 Sustainability reasons:

“Your next heating system could be a more environmentally friendly option - plan ahead and find out about heat pumps”

Figure 4: Cumulative reach of message themes across subgroups

Reach when the heat pump financial support messaging was excluded from the analysis

To understand which message themes could encourage advance planning without relying on financial support, we looked at the reach when MT2 Heat pump financial support was removed. This is particularly relevant for businesses that do not offer heat pumps and therefore are unable to refer to the BUS grant, or offer a range of heating options where the BUS grant may not be available. 

When MT2 is excluded from the TURF analysis we found that MT7 Planning ahead to avoid disruption was the most compelling message theme. It reached just under half (47%) of homeowners (see Figure 5):

“Planning ahead for your next heating system means you won’t be left without heating or hot water when it matters most”

Figure 5: Impact of combined message themes using Total Unduplicated Reach and Frequency (TURF) - excluding MT2 Heat pump financial support (%)

When MT6 Help & advice to upgrade was added to the first MT7 message it increased the total reach to nearly two-thirds (64%) of homeowners - that’s an increase of 16 percentage points:

“Most people don’t know where to start with upgrading their boiler. Get Help & advice here from trusted experts and organisations”

The third message theme to maximise influence was to include MT8 Sustainability reasons,  pushing reach to 73% of homeowners:

 “Your next heating system could be a more environmentally friendly option - plan ahead and find out about heat pumps”

The remaining message themes contributed to smaller incremental gains.

Tailor messages for homeowners with children and those undecided about heat pumps

We examined how reach changed across different groups of homeowners when financial support was removed and found that MT7 Planning ahead to avoid disruption consistently had the greatest reach across all subgroups. 

In most cases, the second highest reach was MT6 Help & advice to upgrade, which was true for 18 out of the 21 subgroups, this included demographics such as age, employment status, urban/rural dwelling, household income, age of heating system, and expected stay in current home.

For homeowners with children, MT5 Plan ahead - risk of cost/impact on breakdown emerged as the second most effective message theme with 63% reach once combined with MT7. It suggests that families with children may be particularly sensitive to the potential disruption or costs associated with an emergency boiler replacement (see Figure 6). 

For homeowners who were undecided about, or had previously rejected heat pumps, MT8 Plan ahead - sustainability reason ranked second with a respective 60% and 67% reach once combined with MT7. It indicates that sustainability messaging may help engage and motivate homeowners who are hesitant about adoption of new heating technologies, framing the decision as a positive and forward-looking choice.

Figure 6: Cumulative reach of message themes across subgroups - changes / deviations from most common messages are highlighted

The third highest reach message varied by subgroup, though MT8 Plan ahead - sustainability option was the most common. When combined with the previous two messages - MT7 Planning ahead to avoid disruption and MT6 Help & advice to upgrade - the reach increased to between 69% and 75% of homeowners across the different subgroups.

These differences suggest that while most message themes perform similarly across the population, tailoring content to specific household circumstances or attitudes towards heat pumps could enhance engagement and encourage early boiler upgrade planning. Overall, even without the government grants message, a carefully chosen set of messages can still reach the majority of homeowners and encourage early planning.

Conclusions and recommendations

Encouraging homeowners to plan ahead for the replacement of an older boiler has the potential to significantly reduce the stress and inconvenience associated with last-minute purchases. More importantly, as the transition away from gas and oil heating accelerates, early engagement gives homeowners the opportunity to consider low-carbon alternatives such as heat pumps. While this may not yet be the right option for all households, it will become an increasingly relevant consideration for more households.

Using messages that are more likely to engage homeowners with older boilers and signposting them to useful information about changing their heating system offers a number of benefits in addition to more general awareness raising about heat pumps. 

• Homeowners with older boilers will be aware they need to make a decision relatively soon so the information will feel more relevant and useful to them.
• If homeowners have been considering switching to an electric heating system this is the point at which they will need to do further research and make firmer plans. 
• Changing a heating system is best done when the old heating system is reaching the end of its life as some disruption is unavoidable when replacing an old boiler, and it is likely that the old system will be less efficient than a more modern system.

This research considers the messages that will be more effective in engaging homeowners. Governments and businesses should also consider how they can most effectively reach consumers who may have older boilers and for whom these messages will be particularly relevant. For example proposals have been made for using GasSafe registry data to identify households with boilers that are more than ten years old, encouraging heating service engineers to discuss options with homeowners that have older boilers, or the possibility of using EPC data. More work is needed on each of these ideas but they could allow for more targeted communication.

Based on our research the right combination of messages can give homeowners the prompt they need to look ahead, consider their options and start planning their heating upgrade before a breakdown forces their hand. 

The three message themes that were most effective were:

1. Financial incentives: government grants and loans could make upgrading your boiler to a heat pump more affordable
2. Avoiding disruption: waiting to replace your boiler until it has broken down could mean rushing big decisions, higher cost and more limited options. Better to prepare now
3. Convenience: Planning ahead is more convenient and allows work to be done alongside other home improvements

The first message alone would be engaging for 71% of homeowners and adding the second message increases the potential interest exposure to 85% of homeowners. Adding additional messages only increased reach by a small percentage.

These results help the government and businesses identify the messages that are most likely to engage homeowners. However, they also highlight a broader challenge for the transition to heat pumps. If homeowners’ priorities are to reduce costs, reduce disruption and increase convenience, it is essential that heat pumps are not only well-promoted but also genuinely affordable and easy to install. Effective messaging can encourage planning, but without addressing these practical barriers, many homeowners may still opt for a like-for-like boiler replacement. 

Recommendations for government and businesses

• Support initiatives that enable targeted engagement with homeowners at key decision points. In particular attention should be given to homeowners with older boilers who are approaching the point where they will need to replace their boiler. This might include the use of data about the age of boilers or using boiler servicing visits. 
• Use regular communications to encourage early planning for boiler replacement, helping homeowners avoid last-minute stress and creating a natural opportunity to consider heat pumps. Nudging homeowners towards new behaviours will help to change established patterns that may not be in their best interests. 
• Focus messaging on what matters most to homeowners. Our research suggests that affordability, reduced disruption, and convenience, are the themes that are most likely to drive engagement.
• Provide accessible information and advice to support decision making. Homeowners are more likely to engage with information and advice at this time. Linking to independent sources of advice can increase consumer confidence and support informed decisions.