Octopus Heat Pump Installation 1930s Semidetached house Chippenham

Octopus Heat Pump Retrofit 1930s Semi Detached Langley Road

Our Octopus Heat Pump journey started in late October 2023. We’d been with Octopus Energy as an electricity and gas supplier for a couple of years and made good use of their Intelligent Octopus tariff. We wanted to decarbonise our house, and the last significant step on that journey was to get rid of gas.

Our house is a 1930s semi detached in Langley Road, Chippenham, and we’d already undertaken a number of mostly DIY energy efficiency measures.

Our existing heating and hot water was through a combi gas boiler which was about 12 years old, and though perfectly serviceable, was old enough we felt to justify a heat pump replacement.

In order to qualify for the Government’s £7500 Boiler Upgrade Scheme (BUS) grant we needed to demonstrate that we had no outstanding Loft insulation or cavity wall insulation recommendations on our Energy Performance Certificate (EPC). This is demonstrated by having an up to date EPC for your house. An EPC is relatively cheap to purchase, costing between £50 and £90, Octopus will even help arrange one. We used a local assessor – Chris Hunt, the EPC guy. It involves an inspection of your house and loft space over a couple of hours with lots of questions on the construction, and measurements of room sizing. You can check if there is already an EPC for your house on the government’s website here …https://www.gov.uk/find-energy-certificate

Our 1930s house had an EPC of B, which was very good for the road. Though in terms of insulation we hadn’t done anything extraordinary. We had cavity wall insulation that had been installed arounds 20 years ago of the fluffy fibre type. We had loft insulation which we’d installed ourselves, and a number of simple draft seals on doors, double glazing, and a chimney sheep. But like most houses of nearly 100 years old, any DIY we undertook would find holes in walls, old pipes, and bits of missing insulation. So it was by no means an airtight Passivhaus; i’d call it a ‘shallow retrofit’. It wasn’t even mouse tight let alone air tight!

So we went online on the Octopus Website here …

https://octopus.energy/get-a-heat-pump/

entered our address, and received an instant online quote of

£2180 to pay after the Government’s BUS grant of £7500 had been applied.

After some discussion with my wife (who was somewhat sceptical on heat pumps) we both agreed that this was a very good price and we should sign up before the available grant or pricing changed. The price included all necessary radiator changes, a Daikin Heat pump and installation, hot water cylinder, thermostat and controls. It doesn’t include re plumbing of your your house if needed or additional radiators.

We had some concerns that our plumbing was 10mm micro-bore, but this wasn’t an issue for Octopus, though they can’t at the time of writing go as small as 8mm micro-bore.

So we paid the £500 deposit to guarantee the quote, refundable up to the day before installation with no obligation.

We arranged an initial phone talk through with Octopus, and this confirmed things like the 10mm micropore, EPC and insulation levels, initial thoughts on where we might put the cylinder and outdoor unit. This all went smoothly and the next stage was a site survey. I was initially told this might be in December 2023, with a potential installation in spring 2024.

The Long Wait

…and so the seasons passed… Winter turned to Spring, and Spring turned to Summer. We enquired a couple of times about our survey and were told it would happened sometime soon, but there was huge demand. We weren’t too bothered about the delay so long as the price was maintained, and we did have a fixed price quote. We speculated that perhaps Octopus simply didn’t want to do the job on such an old house, but I don’t believe this to be the case. I believe the change of the government grant from £5k to £7.5k hit a tipping point for many potential customers and they simply got overwhelmed.

The Survey

Eventually in June 2024 our survey day arrived – hurrah!

The surveyor was very pleasant and went about measuring our room dimensions, asking questions about insulation and construction, and noting existing radiator sizes and locations.

I knew from photographs i’d seen on the ‘Unofficial Octopus Heatpump Facebook Forum’ that a large amount of inside space was needed, not just for the hot water cylinder, but for the expansion vessel and Volumiser cylinder, and the necessary pipework. Consequently rather than try fitting it in the cupboard where the Combi boiler was, we’d decided on a new location in our utility room. Whilst this would mean considerable removal of old cupboards and making space for a cylinder and plumbing, it was on an outside wall where we thought the outdoor unit could go, and was easily able to pickup the 22mm heating pipes and water pipes running from the kitchen along the wall.

I would recommend thinking about where your cylinder and plumbing can possibly go before the survey. Consider where your existing radiator heating pipes run from your boiler, and how the very large 28mm copper pipes can get from your outdoor unit to your indoor Hot Water cyclinder. Also consider where your electrical supply and cabinet to your house is as Octopus will spur off here and avoid touching your existing electrical distribution board.

Noise Requirements and Permitted Development

One of the possible gotchas regarding positioning the outdoor unit is the noise level at your neighbour’s nearest habitable window. We wanted to the put the unit to the side of our house behind a gate. Under Migrogeneration Certification System (MCS) requirements the noise at the nearest habitable window needs to be 42dBA or less. As the Daikin Altherma is rated at 60+ dBA at its noisiest, the nearest habitable window needed to be a number of metres away in for the noise to reduce to 42dBA. In reality they are incredibly quiet, but if you can’t meet this requirement Octopus won’t proceed without Planning permission. Our neighbour’s landing window was opposite, that was OK as it wasn’t habitable, so we needed to measure to the bedroom window. This involved some checks with a laser measuring pointer, but fortunately we were at just enough distance that the noise requirement was met. I wanted to avoid going the planning route as I knew this could involve a noise assessment, and it would be easier to move the outdoor unit and have longer pipework.

The Second Survey

We finished the first survey having reached all the necessary criteria we felt, and waited for the proposal. However after two weeks Octopus contacted us to say they wanted to cross check some items on the survey as the first surveyor was relatively new. So we duly had a second surveyor and an assistant come out.

I wan’t sure why this was necessary, and thought that perhaps they either couldn’t believe that a 1930s house had an EPC of B, or that our heat loss couldn’t be as low as determined, or it couldn’t possibly be as easy a job as it appeared. I’m still not sure, but perhaps it was simply a measure twice install once check.

So we answered all the same questions again, yes the bathroom really is that small, and measured the distance to our neighbours window multiple times eventually resulting to google earth. The second surveyor highlighted we needed to put a new radiator in the kitchen and would need to pay for plumbing to do this. I said I didn’t want to do this as we had run the gas boiler at 50 deg C for the past two years and were fine with the temperature.

So we agreed that we would refit the interior doors between the living room and kitchen such that it could be classed as non living space and treated differently in the heat loss survey. We agreed to do this and the survey completed.

Top tip

Most combi boilers allow their radiator flow temperature to be reduced, for our Worcester Greenstar this was the left rotating control knob on the front of the boiler. Reduce your boiler flow temperature to say 50 deg C, this can be checked with a kitchen food temperature probe on your boiler radiator hot outlet pipe. If you run your boiler for a few weeks at 50 deg C and you’re happy with it, you know you’ll be toasty warm with the properly sized radiators you’ll get with the heat pump install.

The Technical Proposal

Finally some nine months later the Octopus team finally gave birth to the technical proposal for our heat pump installation. It was worth the wait! Below is a snapshot of the radiator schedule.

Octopus Heat Pump Schedule

Octopus Radiator Schedule

Octopus work out the heat loss for each room and calculate the required radiator size

Based on the room by room heat loss calculation we needed a total of five new radiators with three remaining. In many cases these were taking the existing single depth radiator and replacing them with double depth radiators. Though as you’ll see later, in my mind this translated to physically much bigger radiators. The reality was the radiators were deeper, but not a bigger footprint.

At this stage if there are any radiators that aren’t to be changed, but you’d like them changed, it might be worth asking how much this will cost. I ended up changing one additional hall radiator during the installation and i’m glad I did for appearance reasons. You’ll know you have a house full of plumbers so that’s the time!

We duly signed our technical specification and agreed to the pre-conditions of refitting the kitchen doors and preparing space for the cylinder in the utility room.

Finally in September we were offered an October installation date, which being nearly a year from our initial enquiry we accepted immediately!

Preparation

As we were having so much equipment installed in the utility and it hadn’t been decorated since we moved in – we decided to give it a spruce up. As the bathroom was directly above and the ceiling had suffered from leaks over the years, we took the decision to take down the old Artex ceiling which had previously been water damaged, and replace it, allowing us to check the state of joists under our bath above the cylinder.

One of the preconditions Octopus can apply is checking of Artex for asbestos content. As a precaution we had taken a small segment of the ceiling and sent it off to a testing lab for analysis (cost circa £45). This tested negative so all was good.

Once the ceiling was removed. We spotted the insulation wasn’t as thick as anticipated in our flat roof kitchen extension, so I bought some more and pushed as much in the cavity as I could. I also filled in various holes in brickwork with expanding foam to help insulation, and fixed the seal on the bath. Cabinets were removed in preparation for the cylinder and the washing machine drain replumbed. So it was a worthwhile exercise.

It’s not necessary to take down your ceiling for a heat pump installations, it’s just something we did as we didn’t want to decorate with the equipment in situ.

Utility Preparation

The Installation

Day 1

The delivery van turned up at 7-30am in the morning and waited a few minutes for the Octopus Installation team to arrive. The team had travelled from Essex the previous day but were fortunately staying locally in the Premier Inn.

Karl and Jake introduced themselves and helped the delivery driver to unload. They were friendly, chatty, and a nice introduction.

Our gravel driveway caused a few issues and everything needed manually unloading from the truck. The heat pump itself had to be lifted manually down the driveway.

The Octopus team used electric vans which was excellent, but did lead to some range anxiety as the journey from Essex had required on the way charging and every fast charger in Chippenham seemed to be out of commission. I offered the use of our own EV charger but the team politely refused.

It was pouring with rain and consequently the unload and delivery was a little challenging. Fortunately the rain soon stopped.

It appeared that a volumiser and drip tray were missing from the delivery, or possibly lost at the back of the delivery truck (who had two other deliveries to do), and these needed to be ordered. There was a little confusion on my part on the radiators delivered as they seemed a lot smaller than I imagined. I had to admit I hadn’t checked the physical sizes of the ones specified with a tape measure against our room size, and though they were as per the schedule, I had in my mind that the radiators would be physically much bigger.

In all cases the radiators were deeper, but in most cases they were physically smaller. Karl did query one radiator and said he would see if there was an alternative as though as specified, he felt it wasn’t aesthetically sensible to put such a small radiator under a high window.

After a walk through with the radiator schedule, checking which radiators went where and how the unit and cylinder could connect, the team cracked on with draining the system, installing the first radiators, and starting the cylinder work.

At lunch time the Octopus Electrician arrived, having driven all the way from Essex. He too had range anxiety! I gave the electrician a quick run over of the electrical cabinet and how I understood the installation would go. He seemed very competent and worked extremely quickly putting in the new board ready to connect via Henley Block into our meter tails, and a separate mini distribution board near the heat pump location.

The team left us with hot water restored from our combi boiler and temporary fan heaters for heating. All in all a very good first day and an excellent friendly team.

Days 2 to 4

Early Tuesday morning Ian arrived from Octopus Swindon to remove our gas meter and cap it off. This was a momentous moment and signified the end of a six year journey to decarbonise our house! Yay!

The installation continued with Karl, Jake, and Dan, arriving each morning and generally tackling items in parallel. Karl was the lead installer and so took on the more complex aspects whilst Jake diligently worked his way through the radiators. Part way through Karl swapped to allow Jake some of the more complex plumbing.

I was pleased we were able to make space in our utility and Karl said he would try and keep the cylinder in the corner to allow as much storage space as possible. I hadn’t anticipated just how complex the pipework is and it’s testament to the skill level of the installers. This was Karl’s 25th Octopus heat pump installation.

It was necessary to be present for most of the installation as questions did arise as the installation progressed. I also kept the team supplied with tea and biscuits as I appreciated working away from home in a hotel is a strain.

The team went the extra mile where they could, replumbing our outdoor drain piping to make the whole installation look tidier and offering to change an additional hall radiator if I could collect and pay for it. I appreciated this as this was the one you saw immediately as you entered the house and I hadn’t thought of asking previously.

By Thursday afternoon the system had been filled, powered up, pressurised and the first tests were carried out. As Karl was doing this he ran through the controls and explained some of the set up.

Handover

Karl talked me through the setup of the Daikin Onecta app on my phone, the internal control panel, and the use of the room thermostat. We also talked through hot water schedules, I chose to run at 4am to 5-30am to take advantage of the 7p/kWh intelligent Octopus tariff, and the weekly anti legionella cycle which uses an immersion to get the extra 10 degrees required on top of the heat pump to kill any bacteria. We set this for 2am on a Saturday morning.

I initially didn’t set up a heating schedule but decided to do this later as we prefer slightly cooler bedrooms at night.

To test the system Karl turned off weather compensation and set a fixed set point of 24 degrees C. I was left in no doubt that the heat pump would keep us toasty warm when needed!

Though Karl could have left that night, due to the distance of the install he popped back the next morning to check all had run well and there were no issues. He also arranged for a replacement for a damaged radiator top grill.

Living with the Heat Pump

Though it’s early days we are very happy with the heat pump. So far we’ve turned the thermostat down a little as the house was initially warmer than we’re used to. We’ve also had hot water each day, all day long from the night time schedule, so all good there. Though we will undoubtedly use more electricity, we won’t use any gas, and as the meter was removed by Octopus have no standing charge.

With our night time electricity rate of 7p/kWh i’m now thinking that overall energy costs will be less than with gas due to the efficiency of the heat pump. But time will tell.

Octopus offer a Cost Tariff especially for heat pumps and I will probably download our usage from Octopus and work out if this could potentially be a better fit for us. Though 12p/kWh in three dips, as our house battery is quite small this may be an economical way to run all day.

I’ll either update this post or add a new one on running costs in a few weeks time.

Overall I think the Octopus experience has been slow, but excellent value for money, and well worth the wait. The installation team were professional, friendly, and willing to go the extra mile. I’m very pleased with the overall installation and with the government grant I think it’s amazing value for money given the amount of work done.

I think the biggest barrier for most people will be where to fit the internal equipment. The myths about noisy heat pumps that won’t keep you warm really are just that, myths!