After 6 months of research and headaches I’ve finally got my heat pump successfully up and running. It’s been quite an adventure and there have been some pitfalls along the way I’ve had to avoid. I thought it might be worth sharing my experience in the hope it helps others make the best decision for them.

Background and Deciding on a Heat Pump and Installer

I moved into a detached house (built 1980s) back in spring, with heating and hot water provided by a large LPG tank in the garden. This fed an old Vaillant boiler. As part of the house purchase we learned that the boiler was not functioning and would need replacing. There is no mains gas in the village, with most homes either on LPG or Oil.

This led to me researching options for replacing the boiler. The LPG tank had been moved as part of an earlier house extension and was currently an eyesore in the middle of the garden so I was keen to look at ways to remove it. This led to me investigating the possibility of air source heat pumps, where the government had recently uplifted the grant from £5000 to £7500.

I did lots of research online and quickly realised that the efficiency of a heat pump depended mostly on the competence of the installer. I was now prepared to get an installation done, but had some key concerns:

• It is a large house (200m2) with a double garage converted to a large home office, as well as a newer attached garage built on the opposite end of the house. It's got double glazing, loft insulation (which I upgraded) but no cavity insulation. I was hoping that I wouldn’t need to go down the buffer/low loss header route because of the size of the house, understanding that many of the issues people had with poor efficiency were down to this. 
• Pipes to the radiators were 10mm microbore. I felt that some of these could have stayed but as we are planning on spending a long time in this house, I was prepared to have the entire house upgraded to 15mm copper.
• I hadn’t yet had an official heat loss survey done, but by playing with the app myself, I’d judged the heat loss to be around 9kW. This could have meant a 10kW heat pump which would have needed planning permission, which would take 8 weeks for a decision. I needed the heating fixed by winter as we were currently without any heat whatsoever, relying on an electric shower and dishwasher for the essentials.

I then contacted three different installers who came to the house:

1. The first was a local company specialising in heating and renewables. They indicated I would need a low loss header, didn’t know that the Boiler Upgrade Scheme (BUS) grant had recently increased, and wanted to charge £33,000 for the work. At this point I cancelled removal of the LPG tank in panic!
2. I contacted the second from a map that Heat Geeks had one their website (it doesn’t seem to be available at the moment). He came over but when I spoke about wanting to change the pipes he didn’t seem so keen. By now I was getting worried as we were entering July and I was no further forward.
3. I’d been impressed by the Heat Geeks videos and they’d recently upgraded their website when you entered your postcode, a few more details, and got a breakdown of costs and – critically for me – a guaranteed SCOP. The price was almost 1/3 of the first quote, so I paid the initial £300 for a heat loss survey which was done a couple of weeks later. When the installer came over he spent about 5 hours doing the survey and when I discussed the system with him it was clear he was the first person I’d met who knew more about heat pumps than I did! He was confident no zoning would be required, was happy to change all pipes and replace every single one of the 17 radiators. Even though the heat loss was 8.5kW, after doing some calculations he felt that 10kW would be overkill and there would be enough headroom with a 7kW Vaillant AroTHERM Plus. No planning permission needed! I also wanted to go for a 300L Newark cylinder and Open Energy Monitor for maximum efficiency.

We agreed to go with the Heat Geek installation, with the cylinder and main components to be sited at the back of the garage, with the heat pump sitting outside on the wall immediately behind that. This meant the flow and return valves were literally as short as possible, again maximising efficiency.

I’d seen some horrendous installations on YouTube with exposed internal and external pipework and cables and was adamant that everything had to be hidden – even in a couple of places replacing old boxed-in pipework with new pipes channelled into the wall. As we had only recently moved in I didn’t mind having walls channelled out, but accept that’s not feasible for everyone.

The Installation

It took a couple of months before the installation started, I got lucky with the Newark cylinder as demand (and price) was shooting up but it didn’t end up impacting on the start date. On the first day of the job everything turned up nice and early, and the both of the installers got to work on replacing radiators and replumbing. As we’d expected, it was a big job and took a couple of weeks for them to do, but it was cleanly done. I also took pictures of the exposed pipes which will be useful to check in the future before I accidently drill into them!

At this time I spent a harrowing day in the two loft spaces, fitting 300mm of insulation over the old 100mm. We’d included this in the heat loss survey but I’d been putting the job off for a long time.

Fitting and commissioning the heat pump took another few days, this included building the base. They also put demineralised water into the system to keep it as clean as possible. The house seemed to quickly heat up and we had hot water in the taps for the first time in six months!

The system has been designed with a flow temperature of 45^oC with each room heated to 21^oC for a minimum efficiency (SCOP) of 400%. Most radiators are inoffensive type 21 or 22s, with one type 33 in the kitchen where space is very limited (as it’s under a countertop).

I’ve been using weather compensation with a heat curve between 0.60 and 0.70. The weather’s been quite mild the last month so it’s not had to work hard and I could have had this lower but am aware that you want to avoid cycling. It is, quite literally, a steep learning curve.

It’s been great to not have to worry about managing the heating – the house is constantly comfortable. If anything it’s slightly too warm at night – I’ve tried setting the temperature to fall back from 21^oC to 18^oC at night but I believe the weather compensation overrules that…

I’ve also been tinkering with domestic hot water (DHW) – I’ve always had a combi boiler in the past so never had to think about this before. As you can see above, I’ve got it to heat to 52^oC in the early morning which gets us through morning showers. Then it’s set to go again in late afternoon if needed, just to top up. This was initially set for 50^oC water temperature but wasn’t quite lasting if anyone needed a lunchtime shower after a run. The Newark cylinder seems impressive but because I’ve no experience with tanks in the past it’s hard for me to compare.

Cost

The total cost for us came to £13,000 (Heat Geek took care of the £7.5k BUS so we didn’t have to both with that). Considering the effort of replumbing the house, 17 radiators plus the heat pump, expensive Newark cylinder and monitoring hardware, I was content with the cost. It’s worth noting that there’s currently 0% VAT charged on heat pump installs so it’s a good time to do a bigger job as you’re saving on VAT for all the piping etc.

The heat pump installation probably cost us an extra £10,000 over simply replacing the boiler, but then I’d have had LPG deliveries to arrange, standing costs for the unsightly LPG tank, and wouldn’t the positive environmental impact. I’m getting solar PV installed in the next few weeks as well which I expect to lower our heating costs further in a way that is simply not possible with gas.   

Issues

Costs: still much cheaper and easier to go with Octopus or British Gas, but a cheaper install tends to have a trade off with increased running costs. I expect as more installers become more competent this should be less of an issue. In my opinion Heat Geek training should be certified by MCS or someone and have a proper Heat Pump qualification to give consumers confidence, and guaranteed SCOP is a big step forward.  

Monitoring: I have got Open Energy Monitor (OEM) running but am not sure how to access the detailed metrics that I’ve seen other people use. I definitely don’t feel like I’m using this to its potential yet and it would be helpful to have a full walkthrough somewhere.

Conclusion:

I’ve no regrets about getting a heat pump fitted and some of the articles I’ve read in the press have been verging on ludicrous. The industry is still not very mature and the BUS grant, like solar grants before it, draws some of the most unsavoury characters out of the woodwork. As long as you take the time to find a knowledgeable install, preferably backed by a scheme like Heat Geeks’ guaranteed SCOP, it can be relatively straightforward. The challenge is that compared to fitting a new combi boiler, there’s an awful lot for the standard consumer to understand.