Heat pumps for building heating are a new technology to most of us, so it is important to know what to expect of their operation and to know what you can do to optimise it.
The day-to-day
Like boilers, heat pumps need to be serviced annually by a specialist who is accredited by the manufacturer. This ensures that the system is functioning safely and the warranty remains valid. Consider setting up a maintenance contract to cover both the planned maintenance and reactive maintenance in the event of problems.
Maintaining a maintenance logbook can be useful, particularly if responsibility is passed every few years amongst a committee. As well as service dates, the log should record details of any issues reported, the resolution of them, spare parts used and so on, to help track changes and improvements to the system over time. It’s also important to update the operation and maintenance manual when changes are made to the system or it’s recommissioned.
During the handover, the installer should have explained what to expect as “normal” or “unusual” behaviour. For example, it’s normal for the heat pump to defrost for a short time during cold weather, but if users report loss of heat every half hour, that could mean there is a fault with the defrost cycle. If something seems wrong, report it to the maintenance team so they can check it out. The installer should clearly explain what normal operation looks like.
Heat pumps and their control system have lots of settings, all of which can be tweaked to improve the system over time. Even if your installer did a good job, there’s always room for improvement. Small tweaks can lead to big energy savings, especially in larger buildings. It’s worth paying attention to how the system works and sharing your observations with the installer or maintenance contractor. Think about things like rooms that don’t heat up well, how the heat pump behaves in different weather, and if the thermostat in one room is affecting others.
Keeping track of energy use and efficiency is key to getting the most out of your heat pump.
Metering
Alongside your electricity supply meter, it’s useful to have an electricity sub-meter to measure the power being used by the heat pump and, in the case of air-to-water heat pumps, a heat meter to measure heat production. These meters may be basic, allowing you to record a reading every week or month. The meters may also be more complex, including loggers allowing you to get half-hourly data, and they may be automated, allowing you access via an app or manual.
Whether you choose to use an automated app or manual reading, it’s important that you record the energy consumption of your heat pump and heating system.
Recording the data and looking for trends can help with:
- spotting faults in the system
- spotting a failure to deliver on efficiency expectations
- optimising efficiency
- understanding your electricity bills
- determining the benefit of adding solar PV if not already installed
- billing for the use of the space
- understanding the best tariffs for you, including variable ones.
If you plan to record monthly totals, you can easily record them in the operation and maintenance manual. However, if you’re collecting half-hourly data, you’ll end up with a lot of information quickly. It’s important to have a plan for summarising this data for committee reports and making sure the next person in charge can use it effectively.
Expectations for energy bills
As part of the project planning, you’ll have examined your previous energy consumption and estimated the energy usage of the new heat pump. Since the efficiency of a heat pump efficiency is lower in winter than in summer, the electrical energy required to generate a unit of heat is higher in winter. In the figure below, which plots the cost of generating a unit of heat over a year (based on weather data for North East Scotland) there is a swing of around two pence between the warmest and coldest times of year.
Health and safety issues
You should ensure that your contractor is following all the relevant health and safety regulations and that a certified installer signs off any electrical works.
Depending on the type of refrigerant and the location of the heat pump, there may be other maintenance issues to consider with respect to leaks, including working in confined spaces, risk of explosion and toxicity. Potential risks should be discussed with your installer and be covered by the operation and maintenance manuals.
As with any heating system which generates hot water for domestic purposes, you must ensure that it is maintained according to the Approved Code of Practice and that your system can generate and maintain the necessary temperatures to avoid bacterial growth.
If things go wrong
There’s always the risk that part of the installation may experience a fault, either through wear and tear, a faulty component or poor workmanship. The operations and maintenance manual should describe how to troubleshoot basic things like loss of power and how to shut down or isolate the system in the event of a fault, and you should familiarise yourself with those processes.
Before reporting a fault, try to identify what it might be and build a clear picture of the problem:
- Is the power to the heat pump on?
- Is it cold in one room but not another?
- Is the air temperature in the space with the control thermostat lower than the setpoint on the room thermostat?
- Is the control system set to automatic or manual?
- Is there a leak somewhere?
Knowing the answer to these and similar questions can help the installer to suggest likely solutions over the phone and plan their visit if a call-out is required.
In theory, wear and tear should be limited if you are following the maintenance procedures. The operations and maintenance manual should describe the maintenance and highlight those parts of the system which may need to be replaced at intervals. If it’s obvious to you that the problem is wear and tear, and you have a maintenance contract, it should cover call-outs to repair this type of fault. Otherwise, you should contact the installer or other specialist.
If you think that the problem may be caused by faulty equipment or poor workmanship, then your first port of call should be your installer (or main contractor). Where the product and the installer are MCS-registered, there is a clear process to follow to alert the installer to the issue, to raise a complaint if they do not resolve it and to escalate the complaint to MCS if they do not respond adequately. See ‘What to do if things go wrong‘ for details.
If your system or installer is not MCS-registered, then you should still follow the same procedure of alerting the installer to a problem, but the support to reach a resolution may be different, and we recommend contacting Citizens Advice Scotland or Home – Trading Standards Scotland for advice.
Know what your equipment warranties cover and when they expire. This way, you’ll know what you might have to pay for and what is covered. Make sure this is clear before your installer does any remedial works.
Finally, bear in mind that a fault may not necessarily be a breakdown. If the system consistently performs less efficiently than expected, then it may be that the likely performance was oversold to you. In this case, the installer is still required by their consumer code to deliver on expectations and the same dispute resolution support will be available to you.
