Hi,

My Grant Aerona was installed under the ECO4 scheme by Eco Providers Ltd (assume they are the same - in Lancashire), and they did an 'okay' job and I suspect limitations might be as much around the Grant advice on how to install ASHPs.

I'll run through what I got, what they did, and my thoughts on good and bad points, which might help you. I suspect to some extent it'll depend on who (which individuals) you deal with within the company.

They installed:

• additional loft insulation
• 100% new pipe work (I had an LPG boiler with microbore piping) in 15 and 22mm (29mm from the ASHP)
• new radiators downstairs (4 x K3, 1 x K2, 1 x P+)
• Grant 10kW ASHP
• new unvented HW cylinder (i.e. the rest of the stuff needed with an ASHP installation)
• fitted trickle vents to windows that didn't have them; added 'always on' silent fans to kitchen and bathroom

The process was:

• phone calls and paperwork to get the ECO4 funding approved (it's based on a "letter of intent" from your local council - once this happens companies swoop in for that government cash and you might get several companies cold calling you, based on your EPC rating)
• initial survey and measurements taken to do heat loss calculations (this assesses what is required to make house work with HP, and you sign things to say you'll take all or nothing - this is an ECO4 requirement; it's not pick what you want)
• second survey to discuss layout and changes required (e.g. pipework, location of HP, radiators)
• loft insulation fitted (2 guys for 1/2 a day)
• heating engineers turn up to isolate old boiler, rip out and lay new pipework, add radiators, HP, etc. (7 or 8 men for 2 days)
• electricians turn up to connect up HP, fit ventilation, and do handover (2 men for 2 days)

Good Points

Loft insulation was very well done (sadly the heating engineers ran pipes thru loft space, so most of that good work was undone). New pipework obviously very disruptive, but fitters mostly polite, cleaned up, and put in long days. Radiators fitted well, and TRVs etc on all save one per zone where room stats located. HP works and the house is warm; HW ample (for me).

Communication with office was good, in that they responded to phone calls, but they weren't HP people, more office/admin.

From start to finish it was 2 months for the whole process (initial survey to installed). I was without heating and HW for 7 days.

Bad Points

Some things mentioned in the two initial surveys didn't happen e.g. extra in room/ceiling insulation for flat roof extension.

The house was split into two zones, and I didn't find this out until it was done. So double pipework, and Zone 2 is a third the size of Zone 1, so the HP is over-powering that zone when it's the only one active.

The two biggest issues are probably evident from the process - when the heating engineers left, there was no power to the HP, so it hadn't been commissioned; the electrician was the one who actually turned the HP on, and the handover consisted of "here's the room thermostats - if it's too cold press the + button; too hot, press 'off') and a stack of manuals left on the HW cylinder. I'd asked for the heating design but only got a pencil sketch of pipework, altho the heating people seemed to have schematics and spreadsheet like data on their phones, so I suspect correct heat loss calculations had been made, but they just weren't shared with me. I didn't feel that involved in the installation. They were in and out as quickly as possible.

Secondly, most everything was left in a "factory default" set-up. Weather compensation was off (fixed LWT of 55C); 3 x 1 hour DHW periods per day; pressure was set at 2.5 bar (by the electrician); HP output flow at maximum; internal pump at maximum; flow regulator at minimum; auto bypass valve set to minimum.

My advice

There should be a return visit by a trained heating engineer once the HP had been switched on to configure the system to the designed flow rates; balance the radiators; set up the heating controls, etc. None of this happened, and I've had to figure it out for myself, post install (partly my fault as I would probably have insisted on these things had I been paying, but I was mainly just happy to get rid of a 30 year old LPG boiler and the connected rusting gas tanks).

Be forceful and demand to see the designs, ask for the heat loss calculations (they definitely did these as the rads are correctly sized), design temperature (and flow rates these relate to), controls to be used, and any zoning plans.

Make sure it's actually 'commissioned' rather than just 'installed'.

@mikefl this is really informative, and echoes many of the experiences of those of us who have had Grant ASHPs installed. So you're yet another Grant install where the WC was not enabled. I had exactly the same, plus primary and secondary pumps on max, thereby unbalancing the low loss header with far too high a primary flow, DHW on two timed periods morning and night when you really want the heating to be on, and when the outdoor air is not at the daily highest temperature, heating controlled a very clunky and inappropriate HIVE thermostat, DHW on a even clunkier and quirky digital timer. It could all run off the Chofu controller. And that was how the Grant commissioning technician left it! He couldn't get out fast enough, there was no handover as such.

It's all running nicely now 'open circuit' on pure weather compensation, and running with a reasonable SCOP, despite sub-optimal and unnecessary hardware like the secondary pump and LLH. The TRVs are simple overheat limit devices in each room, HIVE rad valves simple zone control valves, either on full flow to rad or set back to anti-frost.

Thanks for the replies folks, especially @mikefl. All these points are really useful. I appreciate what you say about the commissioning etc, however I'm more concerned about the installation than the commissioning. I feel like that is something I can research and learn to run properly myself, whereas installation issues are obviously something much more complicated. Please correct me if I'm wrong, and I'll definitely push them for schematics and proper setup info. I'm fortunate in that I'm completely renovating the house currently and all the plasterboard etc is off so I can push them to install pipes inside walls, and put rads etc in the most economical places. It also means they can't make mess of the walls etc.

If anyone has any further comments on installation things I should push for (such as controller in a specific place etc) that would be helpful.

Now to learn what all these terms and concepts mean!