SBMS

Are you diy installing the ASHP or using an MCS accredited installer?

So we’ve just been down this route. Initially we were going 100mm pir but after looking into it decided to go blown EPS beads. I increased cavity to 150mm (should be fine if you’ve standard width foundations). Ours is also exterior facing brick. Cost difference: 272 m2 of cavity insulation required : about £4900 plus the labour for the brickies to fit. Pumped insulation by outside specialist contractor - £4200 - with a 25 year guarantee. Means the build will go up quicker (brickies just focus on laying block and brick) and have a much greater chance of a fully, well insulated cavity. FYI the beads are water resistant and don’t transfer water across the cavity. Water that does get into the cavity naturally flows down the beads between the balls rather than across the cavity.

You can apply the same logic to every single item you might put into a self build. PV? Battery wall? Solar water heating? Rainwater harvesting in case water rates go up? MVHR? 150mm insulation? 250mm? 500mm? It’s pretty much an endless list of options. With an unlimited budget - sure, I’d go for every single one. Unfortunately I don’t; so every single decision that we make weighs up the cost versus risk versus return on that capital investment. In isolation it’s probably easy to say ‘it’s only 1k’. But they add up and this was why I was asking those more experienced in electrical current loading whether this particular investment would make sense.

Out of interest @Carrerahill what sort of a load would justify 3 phase?

Thanks this is really useful and I’ve definitely learned something tonight. The person at the DNO did say they’d only had 3 properties in a year that could justify the upgrade to 3P so maybe it’s be ok?

FYI the DNO offer a scheme where if you can demonstrate an insufficient single phase supply owing to the installation of green appliances (ASHP, car chargers etc) then they will upgrade the supply to three phase free of charge. This is only relevant for an existing single phase supply. Would my scenario demonstrate this?

Sorry are you saying that in my scenario with those 4 appliances operating they wouldn’t draw 100A off the supply? Or are you saying the DNOs capacity calculations wouldn’t see this as a valid scenario?

I’ve been told single phase is 100A and 3 phase is 80A per phase for a total of 240A

Yes this has been my consideration. If i turned on: Oven: 13A Hob: 32A ASHP: 23A Car Charger: 32A then boom... I've maxed out my 100A single phase connection.

Thanks @PeterW. In North west - Electricity North West. £1500 for single phase connection, £2500 for three phase ?

We are in the process of getting mains electric to our site and are deciding between single phase and 3 phase. I am trying to work out the max current draw of our designated ASHP - a Nibe F2040-12. It has in its technical docs a max operating current of 23 Amps - Heat Pump 22 Amps - Compressor Does this mean the unit could draw 45 Amps or am I mis-interpreting?

Does a PV array to give a return on investment for offsetting ASHP electricity costs? A large proportion of running time will be when it’s dark so probably only a few hours offset with a PV array. Could use batteries but again, how many years before payback? I’ve heard that PV array costs have gone up with latest chip supply issues as well. It’s something I discounted when researching as I couldn’t make the maths work. But if electricity costs keep increasing maybe it makes more sense?

Generally you sign up to a supplier for 24 months and they transfer ownership of the tank to themselves. At that point only they can fill it. Once the term ends you are free to find another supplier and the process happens again.

Great source of what’s currently out there: https://forums.moneysavingexpert.com/discussion/1003291/bulk-lpg-cheapest-suppliers-supply-route/p381 Current fix price contracts are hovering around 40ppl. My parents are on 38ppl with a 4ppl surcharge due to rising prices to 42ppl (extragas, north west).

Interesting! How about nibe? We’ve been recommended them by our installer.

True, but ecodan/vaillant/nibe ~12kw variants aren’t. I often wonder what the difference between a 2500 and a 5000 ASHP is…

Is 11% adoption across Europe significant?

As I mentioned on a previous thread… a good 12kw ASHP is 4K+ (Nibe or similar). Unvented cylinder - 1k. 100l buffer - £500. Controllers and pipe work £250. I would argue this is a much more realistic price for a diy install. That doesn’t have a 7 year warranty. I’ve been quoted 11k for a Nibe install. With a 5k voucher the end cost is less than I could DIY install. That’s for a good, branded, warrantied ASHP mind, not a 2k eBay one.

I think you’ve probably hit the nail on the head here. I guess it’s more than just the economics of it, and comes down to balancing the type of house we want to build, predicting future energy costs and how much we dedicate to greener technology.

Agreed, I guess it’s like all things - the greater the demand, the cheaper the supply. And they are still a minority technology that isn’t deployed at the same scale as traditional boilers. So I guess one way to shortcut mass market deployment is to subsidise. The same cycle is happening with electric cars - more expensive technology is being subsidised by the government with a target ban date of the old technology (ICE vehicles). In the EV market it’s pushing mainstream adoption of electric vehicles - which pushes private companies to innovate and scale up and bring the cost down. Same thing will no doubt happen with ASHP but someone (government) needs to nudge behaviour to create the demand.

Agreed that there are bad apples. Wait for big players like octopus to do ASHP installs (they have invested massively in training thousands of engineers in readiness) and are gearing up this year for mass market installs at close the the price of a gas boiler. Now that’s a market force that will really correct the behaviour of SOME installers over charging.

I think the problem is that most people buy based on economic factors. The fact remains that an air source heat pump (at least a good one), buffer, and cylinder costs a lot more than a cheap combi. So economically there is no incentive for the average purchaser. It’s a different game when we are talking on his forum, as self builders, that generally are not as economically constrained and want the ‘best’ not necessarily the cheapest. One could argue the scheme shouldn’t benefit self builders who could afford an ASHP and probably don’t need the grant to make their decision. But I suspect that of the 450million being provided in grants, the number provided to self builders is vanishingly small. My parents for example, living in a well insulated new build with a combi boiler have zero incentive to swap to ASHP or renewable heating - without a grant. In actual fact the problem is that the market has set the price - and hydrocarbon based heating is way cheaper. Market forces often encourage the opposite behaviour that we might want. I can say this as someone who is absolutely being driven by this force! Do I go for the, ostensibly ‘cheaper’ solution - and stick a gas system in or do the ‘right’ thing and choose greener heating. Well the decision becomes much easier knowing that the capital outlay is nearly balanced between both with a £5k voucher. Were it not for increasing electricity costs it would be a no brainier for me at this point to go ASHP. Like all things self build it’s probably not as massive a decision as I think it is, but I find myself agonising over these elements of my build!

If you have a look at page 33 of the previous document the government response states: “We maintain that hybrid systems – a system comprising of a heat pump and fossil fuel boiler – will not be eligible for the Boiler Upgrade Scheme.”

Hybrid systems aren’t eligible for the Boiler Upgrade Scheme.

I believe the consultation closed last year and the government response confirming the scheme published here in October: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1026446/clean-heat-grant-government-response.pdf