@derek-m im hoping they do, they asked early on Friday for my MPAC or whatever the number is on my bill and this was passed on, not sure of having 2 numbers on my bill makes it worse, 1 for standard electricity and 1 for economy 2000, got a phone call at 18:00 stating it was delayed or cancelled  due to unit being too big, I explained it was going from 12kw down to 5.3kw, they said they put this across but peak current is too high. 

It was to late in the day to contact Grant to find out what Peak current is of the 13kw model,  I have since read as above the 10kw ASHP can be installed so if I cant get the 13kw unit I will ask for the 10kw hoping it will be sufficient.

@waylander

Did your installer carry out a heat loss calculation detailing the before and after improved insulation?

This isn’t overly helpful, but as a comment I find it disturbing that the UK announced its bold electrification plans where air source heat pumps are key to actualising the vision, and we have scenarios where DNOs aren’t approving installations. Instead of saying no and rejecting the application, should this not prompt DNOs to upgrade networks so that they can handle peak draw? 

Specifically on the subject, Scottish Power are our DNO, and we had to apply for approval for our 18kW ASHP - it took six months, but we did get an approval to proceed.

@editor

I do believe that both National Grid and the DNO's are gradually in the process of upgrading the electricity distribution systems, but you must realise that this is not a 5 minute job and the costs are quite considerable. I suspect that the politicians and probably their advisors don't fully understand the complexity and timescales involved. Whilst I was working for National Power in Pakistan, a Unit Transformer developed a fault and caught fire, a replacement from Brazil had a lead time of 18 months.

It is also not just a matter of installing thicker cables, but also upgrading the switchgear and transformers on the system, which get larger and more expensive the further you go back up the distribution network.

Whilst the politicians may think that it looks very good in their manifesto's to champion heat pumps and EV's, along with solar farms and wind farms, I do believe that they think that energy gets from the generator to the consumer in some form of magical way.

I still maintain that they are putting the cart before the horse, and should instead be championing energy efficiency first, which should reduce the need for much of the system upgrades that are hopefully being planned.

The powers that be should also be encouraging battery storage systems, both domestic and within the electricity supply networks. This would allow the peaks and troughs of the supply and demand to be smoothed out, and hence once more reduce the need for extensive upgrades to the distribution networks. 

As I have stated repeatedly, if you don't need the energy in the first place, then it doesn't need to be generated and transmitted.

Let's have some grown up thinking for a change.

You can check the ENA database and it will tell you what the max demand is as well as if it is connect and notify or not.  

easiest solution is to switch to an alternative ASHP. You can check the alternatives, again on the ENA database.  

ENA Database link at bottom of page

Here’s some feedback from the Heat Pump Federation on this topic:

On the Energy Networks Association (ENA) data base the Grant Aerona 3 HPID13R32 is not a "connect & notify" model, but there is likely to be other air-source units of this capacity that are "connect & notify". There is a significant degree of confusion around what DNOs will do for free. The Department for Business, Energy and Industrial Strategy (BEIS) has said in the past that all DNOs will upgrade fuses to 100A for free, this is not currently the case. DCP 205 (under the Ofgem governed DCUSA Agreement that governs DNO activities in this respect) sets out what is currently socialised costs. This is all likely to change in April 2023 when the new EDII charging period starts.

Bottom line is that a great deal of work is being done in the background to ease heat pump deployment at domestic level. In the short term, it's worth installers and homeowners seeking out devices that are "connect & notify" where possible.

Another reply from an experienced engineer on the subject. Very interesting: 

I've had a pantomime with my DNO Northern Powergrid - very similar issue. I had planned to install a Grant 13kW ASHP, needing a 32A MCB and isolator even though the maximum full load current is 23A & inverter soft start compressor. The DNO wanted to charge me about £800 to upgrade their incoming fuse from 63A to 80A. Our village has a 'fragile and ageing' DNO infrastructure (I choose my words carefully mindful of the number of power cuts we routinely suffer)

We've got round this issue by revisiting the heat load calcs for the property, and reselecting on a 10kW Grant ASHP (actual capacity 11.5kW). This unit requires a 20A MCB with a max FLC of 17.5A. That is compatible with a 63A incoming main fuse under the 'connect and notify approved method'. The DNO only considers the size of the circuit protective devices added when reviewing their fuse rating, and the 13kW Grant unit drops onto a 32A MCB/isolator.

Update, installers came out and did a max current flow check, ie everything turned on, they are passing this to Scottish power, tbf they are really on the ball.

Bit of bad news my huge 12kw tank has srarted leaking at the bottom, nothing major but floor is wet, think its trying to tell me something.

I had no idea the complexity of getting an ASHP, im quickly learning,  once I get the Ok from SP I can get my internal walls insulated.

Fingers crossed, 

@waylander, good luck.

I’ve just been informed via a credible source that they heard a “rumour that Northern Powergrid are now charging for processing DNO notifications, the only DNO to start doing that. I've not got confirmation that is so, but it came from a Project Manager in the renewables who does a lot of install work with them. Totally contrary to the Government's stated objectives of rolling out renewable solutions such as heat pumps. Contrary to the ENA's policy as well.”

Great news, I just received news im good to go, new insulation and some pipework next week with ASHP the following week,

By current boilers leak is getting pretty now, going to drain it on Sunday unless leak gets really bad.

What a difference a week makes. 

Posted by: @waylander

Great news, I just received news im good to go, new insulation and some pipework next week with ASHP the following week,

By current boilers leak is getting pretty now, going to drain it on Sunday unless leak gets really bad.

What a difference a week makes. 

Did you get your original ASHP or did you have to go for a smaller one?