JohnMo

Sounds like loads of PV, battery and generator is required - if you an get mains gas run the generator from that, exhaust heat exchanger, to do the heating while generator is on. And some batteries.

That's a good spot - even Cool Energy say it's a mid point valve

Then don't ask questions you don't want a truthful answer too - which isn't what you want hear!🫣

Email them back and state what you did, they will update the U values etc. Then if you get a fail, get ready to install solar PV to make up the difference.

You have a Vaillant heat pump, I would just install an ESBE electronic mixer (VRG valve and actuator) at the UFH manifold (you won't need an additional pump). Set the controller to do 2x zones, each with its own WC curve. The zone for the UFH, the Vaillant controller will control the ESBE mixer as needed to follow your defined curve. What will happen is if the radiators call for heat heat pump runs at higher temp and controls mixer to UFH. If radiators aren't calling for heat the heat pump will reduce flow temp to satisfy UFH demand only mixer will be fully opened. I wouldn't add any zone valves, leave the radiator alway open and when they don't need additional heat they run just like they are now and it keeps the water volume engaged and full circulation path for flow rate. IVOR mixers are great, but you then need to run the UFH off thermostats, as it will receive a fixed flow temp and you always need operate the heat pump at radiator temps.

Plumbing wise nothing looks obvious. UFH manifold flow meters, do you have those fully open? Fully open allows the heat pump to vary the circulation pump flow to better manage modulation. Your circulation pump doing DHW is most likely running full speed, so 20+L/min. If you have the flow meters screwed down to 1.4L/min you flow will be hitting a brick wall with a small hole in it. This could be the reason for the thump on change over also.

Had a look at mine, and pump doesn't shutdown, it may slow down but doesn't stop. As the paddle moves it doesn't cut flow off, flow basically transitions from one port to the other, with both ports open until the DHW port closed. Assuming the UFH manifold is fully open it shouldn't see an issue. Do you have the piping all clamped up as it should be? No air in the system? If it's water hammer, the pressure wave need something to hit, and bounce back. A photo of the valve and the piping to UFH may help. Assume you don't get any fault codes?

I would look how this is reflected in room layout, some rooms may only need straightening out with self levelling compound, others may need way more, it also depends on the area of the floor how much needs to be corrected. We did all the correction that was needed a short time before floor covering went on.

How are you controlling the 3 port valve and pump - is all via the heat pump controller or something else? What valve are you using?

Did you finish this after topping up system pressure?

Woke this morning, after thinking I had a stable system, with flow temps bouncing about. The bouncing occur soon after a temp drop overnight. System currently looks like 4kW heat pump at min modulation 1kW, UFH with single fan coils (60L), volumiser (50L). UFH is within 100mm slab. Previously 6kW heat pump and at min modulation 4kW, the rest the same as above. For my previous heat pump volume was king to cycle control. Current setup not sure the volume adds anything positive, it adds to system inertia and leads to slow feedback to heat pump. Think the control system is looking for a more timely feedback to changes to running parameters. The thick screed, big water volume (via the volumiser) adding too much delay to changes, such as return temp staying stable for too long after a controller input, so control throws out a further command, feedback comes back (late), so the controller keeps over compensating. We get a yo-yo as witnessed. Luckily the volumiser is easy to bypass, so this was done earlier. Within 5 mins of the change, the flow/return and power input became very stable. Looking at yesterday and todays day time temps they are almost the same, but CoP has jumped from 5.2 to 5.4 during steady running. Will see overnight as temps swing about outside, if this has calmed the down.

Then once all working again, inhibit system with heating system inhibitor and biocide (same brand and type as previously used). Or if you have glycol, add glycol to the correct ratio.

As a country we seem to do A or B, it all too binary. Heat pump or gas, best bang maybe hybrid for a lot of the existing housing stock, 90% of the time running a heat pump, almost zero plumbing changes. Oil & gas, yes or no, we close refineries, export what we produce, then buy it all back at inflated prices. We just import a pretend net zero from somewhere else. The politicians all need a good sacking and be replaced by people with common sense.

Utter nonsense, currently working part time on a new field 20+ years design life, financially its a go, politically it may be stopped. Plenty of other proven reserves, but stopped mostly for political reasons. Same in the north sea. This will the third project I have worked on in the last couple of years, good production rates, all the others stopped due to politics. Existing field development has stalled also due to politics. Anyway most of the oil produced in the UK is mostly sold abroad. UK Production 31 million tonnes Imports 42 million tonnes Exports 25.4 million tonnes - we can't refine it Consumption ~60-70 million tonnes

It shouldn't rise too much, if it does that's an issue. Your system will have an expansion vessel this has a rubber bladder in it to absorb the extra water volume. Extra pressure doesn't aid anything, 1 bar is fine. You pressurise to help remove air from the system, any air vents or bottle traps should be opened to release any air a week or so after the start of the system, then closed again.

Turn off the isolation switch outside by heat pump. Leave it off for a couple of seconds and switch back on. Or if the controller is on its own power supply, switch that off and on again. Doing both will not hurt anything. Makes sense, immersion are generally 3kW so that plus any other loads in the house.

Flick on the immersion for hot water. Looking at the state of the filter/strainer, your system is full of crap. If you have zero pressure in system it will not bleed. But top-up water to get around 1 bar on the gauge you show. Then switch off power to heat pump, this maybe needed to reset the error code. Switch on and see if cleared. If so it should start up. If pressure has dropped again tomorrow you may either have a leak or you heat system expansion vessel has failed.

Milliwatts per km? That will be lots and lots. Think you mean MW per km

Looks like premium brand markings on any old pipe. Just get Pert-Al-Pert 16mm pipe. I got everything from Outsourced Energy. They do Ivor stuff which is good and good service. You only need pipe, manifold and 16mm euro cones, and staples. https://www.outsourcedenergy.co.uk/product-category/pipe/aluminium-core/ My £2100 Haier heat pump is working great, 4 degs outside CoP of 5.1. £500 for direct unvented cylinder

Way bigger per kW. Velocity through heat exchanger certainly seems a lot lower.

We are the same - but no AC. We are NE Scotland and no one needs Aircon in Scotland do they? Our UFH cooling went on mid May and was switched off in Mid September last year. Not as effective as AC, but makes life bearable. Without cooling in the first year, we got lounge temps in the late 20s any day the sun came out - don't matter if it was cold or hot outside. As soon as we had building sign-off, I installed a heat pump purely for cooling the floor.

That's a killer, motivation once in the house is hard to come by. Our roof was going on this time 5 years ago (where has the time gone), but was on mission, motivation was easy, I didn't plan or expect the build to take more than a year, which it didn't - year two would have been much harder. Lists helped me - a list of 10 achievable things, strike them off at the end of each day, anything left add to the next days list - even if you are not doing them and you are paying someone else, you see progress. Progress is a motivator on its own

Just went back and looked for a similar period of running for the Maxa heat pump, similar outside temperature, CoP here is 0.86 lower, doing the same heating. Flow temp was up to 30 degs to compensate for cycling. Haier is flowing between 25 and 26.

I have now been running for a couple of days, and have now got it running in a stable manner. Out the box settings are fixed speed pump and 100% speed setting. There is also a selection to be dT controlled and variable speed circulation pump. If you set to dT control the default being dT of 5 degs. Initial run was on a setting dT of 4 and variable speed. Problem I found was floor return temp was a very stable 23 degs and I had a target of 26 flow temp. So the controller was trying to get return temp to drop while maintaining a target flow of 26. A bit of a mess, plenty of overshoot, then undershoot outside was between 5 and 3 in the 4 hours window, CoP 4.17, ok but not great. Tried fixed pump speed similar results. This morning house was warmer than I wanted, so lowered WC curve and set to dT control and lowered dT setting to 3. Last 6 hours of running - 3 hours spent bring floor temp down a degree, think the spike maybe the energy integral adding energy to floor to catch up. When you zoom in, it's very controlled and deliberate. Then 3 hours running steady state and a CoP 4.96 over the 6 hours. Actually outside temp over the 6 hrs was between 2 and 4 degs. Defrosts, seems very resistant to freezing, only one defrost cycle so far. Took 4 mins and used 0.27kWh of thermal energy.