I spoke with my electrician just now who told me that the original supply (when hp was installed) was single phase but was upgraded to 3phase just after. 

The upgrade to 3-phase was most likely initiated by your DNO.

It's possible that they did stipulate the need for this as a result of communications with your ASHP installer...
... but that he didn't appreciate the significance, and thus proceeded with the work before the supply was upgraded to 3-phase.

That's why we need the correspondence which SPEN sent to your installer.
It should've been included in the documents given to you on completion of the HP work, but there's no problem asking for a copy anyway.

I don't believe Grant offer 3-phase heat pumps.
So if that's what your installer favours, then it's possible he was wary of switching to a different model outside of his comfort-zone.

I’m looking for any paperwork related to the work involved. We had a rewire and a new supply connection just after the hp install. 
I spoke with my electrician just now who told me that the original supply (when hp was installed) was single phase but was upgraded to 3phase just after. 
As I said, I was unwell during this whole period so have not much recollection of the work. 
I’ve obviously been very lax with regard to all of this but 2024 was a terrible year for us, illness, death of a close family member, being sued by contractor and general daily life! 
Sorry for any misinformation, I am only realising now what occurred and when. 
Thanks again. 

customercare@spenergynetworks.com

"Attention Distribution Area Manager for Ruthin:

I have a 17kW ASHP installed at my address <state it here> on <date>

Despite the property having 3-phase available, the installer has fitted a single-phase unit.

Can you please say whether an LCT application was made for this work,
and whether a 3-phase unit was recommended?

Are you able to supply me with a copy of your Consent for the heat pump to be installed?

Many thanks"

DNOs are generally extremely helpful.

They will appreciate your concerns and respond promptly, giving you a case number and named contact.
This is likely to be the Network Planner for the engineering team which covers your area.

You can give them the URL of this Topic, and tell them that you are now following advice from experts within the Renewable Heating Hub membership.

It might help if you tell them that I have a Partnership Agreement with NGED, with access to their internal data.
Although I'm 'just' an ordinary member of the public, that means I am well-versed in matters such as phase-imbalance losses and demand surges. 🙂 

We want to encourage practices which are "grid friendly"!

There's a lot here for me to take in and i don't fully understand some of it so I will have a good read through and take a look at all of the issues you highlighted before I decide what action to take - as I said, I have a poor relationship with the installers so not quite sure where to go from here.

Many thanks again for your invaluable input.

I'm going to assume that what I write here will be shared with Grant and your Installer.
This Topic is 'evidence' in the event that a dispute proceeds and perhaps results in you taking action under the Consumer Rights Act (2015).

Let's see if we can avoid that!

1: The structural integrity of your house wall is compromised.

The material above the large hole is unsupported within the usual interpretation applied by a Building Control Surveyor.

I am a self-builder, with decades of experience across all 'trades'.
(Today I intend plastering an internal wall and fitting coving between it and the ceiling).

Whilst we could waste time delving into the clauses of Building Regulations Part-A (Structure),
I should emphasise that almost all tasks in the construction trades come down to common sense!

If a (large) hole is made in a wall through which pipes or cables are to be passed, then

• the wall above that hole needs supporting by material which can bear that weight (ie not the pipes or cables!)
• the hole should slope slightly downwards towards the outside; thus any rain/moisture is directed out of the property
• the external face of the hole should be finished with a weather-proof finish, no less impregnable than the surroundings (cement render in your case)

Sometimes I line a hole with an outer sleeve which is incompressible, such as a metal pipe.
Or I might take out sufficient brickwork or blocks to fit a cast lintel, which forms the top of the hole.

For a double-skin/cavity wall, whatever lines that hole must avoid allowing heat out, or rain in.

Does your wall have a cavity?

What is the wall made of?

2: We need to know the size of the pipes which pass through that wall, and their composition (copper, polythene?).

When dealing with the low temperatures available from a heat-pump, there is a finite amount of energy which can be transferred along the pipe!

There's no point insulting pipes which aren't of adequate size in the first place.

3: You need to consider what will happen when some aspect of your system fails.

The one we're facing today is the action which will occur if freezing conditions exist outside,
and the internal thermostats turn the heat-pump off because the house is 'up to temperature'.

Glycol is very often used as an additive,
but it has a lower thermal capacity than water.

The more glycol you add, the less heat can be transferred through your radiators.

I hope these issues are now becoming clearer.

I will try to address these issues.

In the event of the external pipe-run freezing, the anti-freeze valves will open and discard all the water onto the ground.

Was this specified?
Was the use of glycol discussed?

I have no knowledge of this so no, not discussed with me...

Thanks.

(external view on left)

external pipe run should be completely sealed against rain.

Should be in pipe diameter of at least 28mm.
The 17kW ASHP has 1¼-inch BSP pipe entry ports.

UV-resistant (solar) insulation wall thickness should be 19mm.
It should continue right through the wall, rather than stopping where expanding foam has been sprayed in.

Support pipe using Munsen rings fitted outside of the insulation.

The end of the insulation nearest to the external ASHP unit should be sealed using an acrylic polymer mastic,
and then covered with 3mm thick Armaflex tape.

The present arrangement allows ingress of water between the pipe and insulation.
This extracts the heat and discards it onto the ground.  😲 

In the event of the external pipe-run freezing, the anti-freeze valves will open and discard all the water onto the ground.

The external unit is protected from damage, but the house will be left without heating or hot water.

Was this specified?
Was the use of glycol discussed?

Frost protection settings are discussed on Page-40 of the Installation Instructions.