JohnMo

At those spacing and if well insulated 25 to 28 will be all you need to flow at. So do have mixer and pump as you are running an oil boiler? Not sure what you mean? 80m loop divided by 40 is 2L/min. You set the flow meter for that loop at 2 etc. Start with the loops at the calculated flow rate. If all open loop you then have to tune the system. If rooms are to warm decrease the loop flow rate, if to cool increase flow rate.

This took 4 weeks, two of us never done it before (working 8 hrs days in Dec in NE Scotland), 70m perimeter, up to 3.5m high at front. Then there was a break over Christmas and new year and roof materials arrived 12th Jan First week of Feb roof on. If you exclude the Christmas break, 9 weeks, not sure where the savings of 3 months come from.

No idea, no idea if the house size etc and how many people live there. MVHR you really need an airtightness of around 3 or your wasting money. Worse than that I would only do dMEV or MEV based humidity control. After moving away from intermittent fans, that are noisy and perform rubbish, wouldn't go back to them. A well thought out MEV or dMEV will yield lowest lowest ventilation heat loss and best control of humidity, with almost no running costs. So humidity controlled inlets in dry rooms, humidity driven fan from a MEV or dMEV system, all doors under to allow ventilation cross flow with doors closed.

I would Self install the PV Pay octopus to do self installation export, which is £250. Then not worry if you are using or exporting. You need an electrical.install certificate, as well as G98 etc, you may need a structural certificate depending how you mount the panels. Keep it all simple.

This does as well https://coolenergyshop.com/products/cool-energy-solar-power-diverter?srsltid=AfmBOoqhPEOh5honAnsCyw0EYcVA8sIS74Zkpt_ENnLL5pn1vo1dzyRM Most don't do two outputs Spending big on diverters is a waste of money, so buy carefully. Pay back can be huge, especially if spending £400 on an Eddi. If you are thinking about a battery, a diverter make no sense and can it other ways more efficiently.

We had similar for our roof, no materials would be delivered until full material payment had been received. We agreed I would pay when the lorry arrived and before it entered the gates. A bit of back and forth, this was agreed upon by all parties. It all worked that, lorry arrived, I did a bank transfer, they check and released the lorry to be unloaded. Push back, say install balance will not be given until install has started and agree a payment schedule. Buying things is a two way street, you have just as much control, you have the money. If you don't get what you want move to another supplier, their loss, generally a few tens of thousands. My windows and doors were all paid on completion of works, except a 10% deposit.

You always have a reserve you can't touch, called depth of charge, my battery is rated at 13.5kWh and has a depth of charge of 100%, so in reality the actual battery is slightly bigger than that. So you need to look at the data sheet and see what you are actually getting, Bit like heat pumps, battery rating isn't always black and white

You have to idiot proof builds, and do what's done locally to great extent or be prepared to do it yourself. Would be my view. Around us it's timber frame kit and brickwork, which I didn't want, so went wood crete ICF and did myself. No walls collapsed or any blow outs encountered.

With enthalpy heat exchanger it should be at a steady 50% humidity. So are you sure it's plumbed correctly - i.e. all extracts to extract manifold and to correct nozzle on MVHR? Go around each terminal 2 sheets of toilet roll. Extracts should hold up the toilet roll, supplies will not. Confirm every one is correct and report back.

Do a factory reset on them first, then a recalibrate on them (it may just be a recalibrate you can do - haven't seen the instructions for a long time). That may kick them into life.

Only up to either a CT clamp on export says no or the inverters limits (e.g. G98) say no Not sure that would work, as the heater would be hot all the time, so hot 24/7 - is that want you want? You have a heat pump, assume that is set up to do the heating/DHW. I would heat DHW to the highest setting the heat pump allows at lunch time each day and also boost central heating around the DHW heating to coincide with peak generation - around 11am to 2pm for both jobs each day. Anything else dump to immersion. Don't get carried away with array size, otherwise you just have a job managing it and it will be wasted. Look at it as a back filler for your normal loads only. Anything above G98 limits can be full time job in summer.

First comment is to do buffer in a 2 pipe configuration - not 4 pipe. Use a 28mm tee at a top and bottom connector of the buffer and the then pipe away from there. You don't need T&P relief on the buffer, but you need it near or part of the expansion vessel (robo kit). You will need a pot water expansion vessel on the DHW cylinder. I would add a filter to cylinder return as well or at least a strainer. Not sure you need a check valve of the hot outlet of the buffer? 30kW is a massive boiler are you sure you need one that big? Control of boiler would be to manage buffer, so sensor from buffer goes to boiler. You do this by selecting a flow temp that suits your floor. So set you buffer about 10 degs higher than the UFH flow temp this will give mixers some authority, your different floors may need different flow temps. Set the mixer on the UFH at say 35 circa start. Over shoot too much trim the temp back. Takes days to get up to temp increase temp - couple days you will be just about there. One adjustment per day otherwise you chase your tail. As the floor takes more heat away on a cold day, the mixer allows more hot water in to manage that. So don't over think it.

You need to check your attachments, as one is a safety cert

As I said earlier, so why come here and look for a rubber stamp, you know what you are going to do.

I followed your lead on this, exact same, fill battery over each cheap cosy slot, if there is excess PV it just gets exported. Doing a predictive charge may save a few pence here and there, but life's too short. The batteries own control does all the work.

Because the work is subject to planning, so a couple of reasons Planning breach: You could be in breach of planning law if you begin work before all pre-commencement conditions are satisfied, even if you have a planning approval. He has zero idea if there are any ore-comme cement conditions or if it will be approved. Your first BR inspection will prior to concrete pour into foundation, no point doing this early as you risk collapse etc. Must have nice weather down south, we are at zero at the moment and it's not been much better for the last week, plus very wet.

It's your call, your risk.

This is nothing to do with pump and it's output, just the static set pressure of the system. So set pre charge pressure at an appropriate setting prior to filling to system and fill until to 1.5 bar on the gauge on you fill loop gauge. Bleed system and then top up. Run system for a week and you will have to top up again as air is removed. But I am operating mine at a pressure of 0.5 bar without issue. The pressure is set that high to make sure you have no air bubbles which render the flow meter useless.

Air test is small fry in the total cost of the build, depends on what you declared on the drawings, anything better than a 10 would demand an airtest I assume (living in Scotland - it was a sign off document for the completion certificate). So look at the requirements for BR sign off

if you want

ICF is easy, and I quite enjoyed the process. Other options worth consideration, block work with external insulation or Larson Truss with dense infill insulation. Both should give thermal bridge free build and great protection from heat and cold.

That's just an expansion cylinder, used to take up space when the heating is on or off to save bursting pipes. The white one does the same for the cylinder. My previous comments assumed WC and modulating ASHP, ASHP will modulate the ASHP circulation pump flow rate to help manage dT. If actual flow rate is capped by a load of flow meters being part closed, that doesn't work well.

I did this last March on mine, basically batch charging floor with excess PV. Most heat pump are able to do two different flow temperatures, normally for an UFH and radiator zone, so radiator zone calling for heat resulting in higher flow temp. Anyway use the zero volt contacts for second flow temperature to force ASHP into action. I did it via home assistant, there are other ways. Currently doing something similar based on outside temperature, if average temp is below 5 outside, I boost flow temp in the middle of the day when CoP is best for a few hours. Then the ASHP site idle for a few hours while floor cools. But this is driven from a signal from a UFH controller so nothing smart going on. If you have a diverter that can do two immersions, use a timer relay to give a decent cycle time for heat pump to one of the immersion outputs. But I think Panasonic can integrate quite well itself given the correct feedback.

We have an ICF house, (wood crete, not polystyrene), it's silent, the only noise comes through the triple glazed windows.

Not sure what the other disc is , but it's the red one you are looking at at the top of the spring. If you are running without a buffer, and secondary pump, you would just open all the valves fully, only closing in one where rooms get too warm. Then let the heat pump controller do the flow rate it needs. You end up with a variable UFH heat output controlled by heat pump.