JohnMo

Just put the inverter in the loft, terminate direct to the inverter, then an AC isolation switch and then down to consumer units. Then you have PV array plugs and inverter plugs nothing else on DC side. Or just use longer DC cables and take then direct to the inverter location planned?

Really depends on heat loss - start with the basics do a heat loss calculation. Then you will know what size you need. 19 radiators in a heat seize of a house and 19 radiators in a low heat loss house require different heat inputs. This will give you an easy means of getting somewhere close https://heatgeek.com/articles/heat-loss-calculations

The reason I said in the first place was, that the flexibility comes from having a big energy store, then you can play tunes with how you heat your house. Pure weather compensation is fine with thin and thicker screeds, batch charge can only be done with thicker screeds. Batch charging can be useful with time of use tariffs. A few on here only heat on cheap rate periods. 40mm is more like a big radiator.

I would size heat pump based on a few criteria Over size ashp approx 1.2 to 1.4 for region of +5 to 0 to allow for defrosting. Make sure heat pump puts out a genuine minimum of 7kW at you design temp. Take note also of oversize to cover defrosting. Get a heat pump with good modulation. Size system volume based on 20L per kW output at minimum modulation of heat pump. Exclude in volume calculation any radiators with trvs and their pipe work. Exclude any UFH loops with actuators. Any volume needed, add by volumiser not buffer.

Pretty rubbish in a premium price point ASHP!

Put in 0 rather than empty. Put 0.3 to 0.5 in the ACH. This figure isn't airtightness its ventilation heat loss calculation. Airtightness does have an impact but its small if you are doing airtightness detailing.

Took my insulation at the wall edge out as far as the inside edge of the skirting. So bottom image but wider. I would do 200mm PIR and increase screed depth.

Via the same search, but direct wording from the Emneti website. The Tecno-Varia vent valves allow for automatic air evacuation, but with the patented Tecno-Varia version and the extra manual vent, it is also possible: - monitor the valve's regular operation; - accelerate air evacuation in specific conditions (e.g., system filling). Those were my words

You really should do an image search and let AI tell you Operation: For normal automatic operation, the top cap should be left slightly open. It also includes a manual vent function, which is useful for rapidly bleeding air when filling a new system. So is left slightly open to self bleed. Side to quickly manually bleed.

The trouble is, ASHP installer comes along and allows air into system. If air isn't fully purged after they finish the piping you get the situation described by @Nickfromwales. For me the ASHP installer should have revisited the purging.

Do you use a second pump (on the heater circuit), or does the system rely on buoyant flow across the heating element - similar to the original design for cylinder heating?

I used something similar on a 2kW heater it has a melt down after about about a month. You need a relay rated more like 20A, to put up with the switching loads. Build or buy something like this, this is what Grant Boilers use on heat pumps to switch immersions. Choose this link because it shows the inside of box. https://ebay.us/m/iXxCKs

So was system off while away, or running normally? What is your normal system pressure?

Not sure if the heat pump installers did the purge, from the answer? Last person needs to purge air and then inhibit.

Your system looks manky. Delete the strainer and install a proper filter is step one. Is system correctly inhibited? Not a fan of glycol if your system is filled with that. If not needs a suitable inhibitor and if a low temp system biocide.

No when it starts, air will come out first. It should collect at the high point. The flow indicator will start to move You need a screwdriver turn the brass bit. Water/air will come out the plastic bit - there should be hole.

To me you don't want Willis on without pump on. So drive a suitably rated multi pin relay from pump switch in wiring centre. Drive and Willis from relay. How you control zones doesn't matter after that. Your flow temperature will be by inbuilt thermostat, but add overheat protection with a pipe stat downstream of Willis interlocked to pump Willis power. So mains to pipe stat, then relay, input. So if pipe too hot Willis is off.

But don't you find the reporting and investigation behind the reporting is lacking. Most nights you get two news articles that should feed into each other, but never do. The other night, one article was about new doctors not being able to find jobs in NHS, being paid for by the NHS, the next not enough doctors to reduce backlog. Why aren't they questioning this state of affairs? Same is true for every sector including energy security. They let people off with news grabbing headlines, that may or not be true, and they just report it without due diligence.

Mine are roof mounted and they wanted a design approval from structural engineer - as a new build that was all done at design stage of the building.

Didn't ask me anything about the components, bit of a tick box exercise really. Structural, electric install certificate, G98 certificate. Would avoid, mine had a melt down after about a year. Plenty of cheap new ones on eBay. Various makes and models. 3.6kW inverter can take huge arrays, if you choose well, some will take double that. Most 3.6kW inverters have 2x MPPTs, below that generally have one.

All your numbers are below, just apply them to your house and then balance the the flow and extract.

Why not make your wet radiators in bathroom dual fuel (electric element) or add another/bigger radiator? A thought for later. I would add a couple of degrees leave for 24/48 hrs see affects and go from there. If you have already tried that go further. One thing with ensuites, if bedroom is cool the ensuite will never be hot, as the cool bedroom just pulls the heat from the ensuite.

Posts and postcrete? I did mine with 15mm thick galvanized plates concreted in place. The end near the house sits on a blockwork ledge formed when we did the foundation. Secured with brackets.

I would unscrew the brass bit and see if that frees things up the brass bit may be so far down they have fully closed off flow and pin has nowhere to go?

Just been revising this thread and looking at pay back, we are now at about 2/3 point of payback at just over 2 years, so will be cost neutral in year 3. Looking at the costs PV panels have dropped in price quite a bit. These panels (second hand) including the fuel costs to collect, came in at £740. Same size array in bifacial 500W panels £525. So the whole system would have cost almost exactly £2000.