The installation of an air source heat pump is often completed by the installing engineer with the support of an electrician towards the latter stages of the install. Rob Dyer, Grant UK’s Technical Sales Support Engineer for the East of England and Midlands, shares a quick guide for electricians and what they need to know about working with heat pumps.
With the number of air source heat pump installations increasing as interest in this low carbon heating system grows, more and more electricians are expanding their skillset so that they can work with heat pumps. While an electrician’s role in a heat pump installation might only involve half a day or a day onsite, it is important that electricians feel confident about heat pump technology so that they can support with the correct set-up of these systems.
In this blog, we will share insight into what electricians should be aware of when they are involved in a heat pump installation – we will:
• share a brief introduction to how heat pumps work
• explain what an electrician’s role is in a heat pump installation
• answer some heat pump FAQs that electricians often ask.
How does an air source heat pump work?
An air source heat pump (ASHP) works by utilising the heat energy from ambient air outside and converting this into a higher temperature for use in a wet heating system. This is achieved through the vapour compression cycle which involves a number of different components. The diagram below outlines how an air source heat pump works.
In electrical terms, the key components inside a heat pump are the compressor and evaporator fan. In brief, the compressor is the component which does the ‘heavy lifting’ in a heat pump.
What role does an electrician play in a heat pump installation?
There are two core steps which an electrician will complete during a heat pump installation:
- Connecting the heat pump unit to the electricity supply – heat pumps will need a suitably sized supply cable and, for most heat pumps, this will be 16A to 32A.
- Connecting the heat pump unit to its controls and wiring centre – a heat pump will always be sited outside so controls wiring from the heat pump controller (located inside the property) will be needed. This may typically be a modBus cable or other cabling. Also located inside will be a wiring centre where any motorised valves, pumps, cylinder and room thermostats will all be wired into – most heat pump systems are similar to a W-plan so if you understand a Y-plan or S-plan heating system, then you will understand a W-plan.
The main stages of a heat pump installation include the removal of the old heating system, plumbing the new system, changing the hot water cylinder, and upgrading or adding radiators – these are the steps usually completed by a heating engineer. An electrician will typically come to an installation in the middle or towards the end of the job when all the components are in place. If you are interested in reading more about what is involved in a heat pump installation, please read our blog about the best practices for installing air source heat pumps.
Connecting the heat pump to the electricity supply
It goes without saying that any installer, heating engineer or electrician who is working with an air source heat pump must be familiar with the instructions provided in the product’s installation manual. With each of the manuals for Grant heat pumps, there is an Electrical section where clear instructions provide guidance for those responsible for completing the electrical connections and set-up.
When it comes to connecting the power supply to a heat pump, a dedicated power supply should be used with a correctly sized circuit breaker. The final power supply connection must be made from a weatherproof, lockable isolator located outside the property. And the cable should either be armoured or run in a flexible conduit between the isolator and heat pump.
In the manual, electricians will find clear guidance on what size of power supply cable they need for the specific heat pump model being installed, as well the breaker capacity.
What is the role of the heat pump controller?
As mentioned above, one area where an electrician will be involved with is the wiring for the heat pump controller. The heat pump controller is essentially the window into the entire heating system, giving heating engineers and the end-users visibility of the system’s operation. The controller will also manage most of the components in the system such as pumps, valves and room thermostat settings.
Given the vital role that a heat pump controller has within the system, it is crucial that it is correctly set up so knowledge of both the plumbing and electricals is essential. This includes understanding how to set up the controller and where to look if something is wrong. When it comes to heat pump heating systems, most issues tend to arise when something has not been correctly set up on the controller.
Grant’s Aerona Smart Controller has a very intuitive set-up with clear questions to guide electricians and installers. Once all of the steps in the controller’s in-built configuration assistant are completed, the controller’s screen can then be used to check the correct wiring and function of each component within the system.
We have a series of blogs and supporting videos which provide step-by-step guides to demonstrate the key settings for the Aerona Smart Controller – simply head to our Professionals Support Centre for heat pump products.
What should electricians be aware of during a heat pump installation?
An important thing to understand is a 10kW heat pump does not mean you need a 50A supply - 10kW is the heating output of the heat pump and not the electrical input. This is the difference between a 2.5mm cable or a 10mm cable.
It is also important that electricians are aware of any specific requirements for the type of heat pump being installed. For example, R290 heat pumps have certain protective zones around the unit where switches or isolators cannot be installed.
Another important thing to note is if RCD protection is being installed, the RCD must be the correct type as most air source heat pumps are inverter driven. A type B or type F RCD is usually required – type A and AC RCD protection are not suitable.
Notifying DNOs
Before an air source heat pump is installed, either the installer or the electrician needs to check with the relevant Distribution Network Operator (DNO) whether the electricity supply to the property has a suitable capacity for the addition of the heat pump. This step can be completed via the online ENA Connect Direct Portal where a few details can be entered and a response provided. If certain criteria are fulfilled, the heat pump installation can go ahead and the DNO can be notified afterwards (this is referred to as ‘Connect and Notify’). All of Grant’s Aerona³ and Aerona 290 heat pumps are compliant with ‘Connect and Notify’ which can make this process quick.
Heat Pump FAQs that electricians often ask
When onsite, the questions from electricians tend to be around the types of cabling required for the power supply, the connections to the heat pump’s PCB and the wiring and connections to the heat pump controller and wiring centre. These areas have been addressed earlier in this blog so here are a few more heat pump FAQs that electricians often ask.
What tools or equipment do electricians need to work on heat pump installations?
No special tools or equipment are required for installing a heat pump but the following items may be handy to have onsite:
• Bootlace Ferrules – these are useful for connecting small core cables to terminals
• Data cabling – some of the wiring for heat pumps is data cabling so having a box or drum of shielded twisted pair or data cable (cat 5/6) on the van is useful
• Multimeter – a multimeter is a useful tool for fault finding and checking resistances of sensors.
What training or qualifications do electricians need to wire heat pumps?
A formal electrical qualification is needed to complete the heat pump’s electrical connections and to sign off work to Building Control. Ideally, electricians should also be a member of competent persons scheme (CPS) such as NICEIC or NAPIT . In addition, having solid knowledge of heating system wiring is invaluable and it also helps if electricians have an understanding of hydronics and plumbing.
At the Grant UK Training Academy, we have a dedicated section about the wiring of our heat pumps on both the Aerona³ ASHP Installer Course and the Aerona 290 ASHP Installer Course.
How easy it is to install a heat pump if your background is purely in electrical work?
Plumbing and electrical are two very different disciplines but there is no reason why both trades cannot be learned. As well as the competency, there are the necessary qualifications needed to be able to carry out a heat pump installation. For electrical, this would involve being qualified to the latest version of BS7671 and with plumbing, you would need to have an unvented cylinder qualification, Water Regulations qualification, as well as the usual plumbing qualifications.
There are also heat pump specific qualifications available, such as low-temperature heating system courses – for example the OFTEC Installation, Commissioning and Servicing of Air Source Heat Pumps qualification.
Heat pump resources for electricians
If you are an electrician interested in adding heat pump installations to your offering, Grant UK can help. In addition to training, we also supply a wide range of wiring diagrams to suit different installation scenarios, and we have heat pump specialists available at the end of the phone to provide technical support.
There is also a webinar available on the Grant eLearning Academy which is for electricians, explaining more about how air source heat pumps operate and going into more detail about the electrician’s role in completing heat pump installations. Here’s how you can join the Grant eLearning Academy:
1. Visit the Grant eLearning Academy to create your account
2. Save your password for future logins
3. Enrol to watch our Q&A Heat Pump Webinar for electricians via the course catalogue.
You can also speak to your local Grant UK Sales Manager if you wish to learn more about Grant heat pumps.