JohnMo

Sounds like a plan. Mist spray joints and use expanding foam. Allow to gel and push together this should give bridge free joint. Forming a single wall of EPS. You could use a similar method to stick to substrate plus mechanical fixings.

First thing that jumps out is the lounge is small compared to other rooms, the hall looks bigger. Maybe move stairs towards kitchen diner would balance things a little and possibly a narrower hall, would give a nicer lounge. Utility looks a little small to be practical. Office looks wrong in the corner of the kitchen. The island in the kitchen looks a little close to the door, so is a bit of a pinch point. From a practical perspective would the kitchen in a L shape be better or even swapping kitchen and dining rooms around? So not filling a whole wall. Washing up against a blank wall is just sad, so maybe re-home sink. Have a trip to a beach and draw each floor in the sand full size, walk through the build to see how it really feels. Make changes as needed, photo update plan. I found that to be best for our build.

Pretty much what @Beelbeebub did, but with some flashing to joint to tiles system. Looks way more adaptable/flexible to different sizes of PV panels. Especially if the panel has reduced in size like I found.

This video shows you what you need and how it works https://youtu.be/iHRdlLeqm7Q?si=R62xc2Xma48Hjr-U

After you have done that you need to address a few other things to get best efficiency. Assume a mixer valve and additional pump are on manifold, look to remove them so you can operate on WC. The mixer will always add distortion to system as there is always mixed in return water to flow. If you have a buffer you need to delete or ideally modify to be a volumiser on the return line only. Then look at your circulation pump logic. You need to it switch on off with the ASHP compressor, not be on 24/7. Look at you 3 way valve that diverts flow to cylinder or heating, check make and model, then find kvs value from manufacturer datasheet. You for a kvs no lower than 6, but the bigger the number the better, if 10 or above that is great. Strainers in system, replace with a low pressure loss central heating filter. Strainers have a pretty huge pressure loss, ball valve strainers are the worst.

Simple way is remove actuators. Set target temp in any room to max, so you always have a call for heat, this will ensure pump on manifold runs, or just join the call for heat wires together if there is no pump. Use the room stats as an easy reference room temperature for the next bit. Open all the manifold flow meters to fully open. This will allow the ASHP to work at target dT without fighting the closed meters. Any room that is always hot trim down the flow to the loops in that room. If all rooms are hot, trim ASHP target temp on the WC curve.

No they didn't do it as good as I wanted, so went DIY.

That should read kW. Are you sure that's correct - you end up with a very small number. The number I have seen is to simply divide kWh of gas used per year, by 2900 for gas or 290 for oil. This used the assumptions as stated by @marshian. But the rules in addition to that are This assumes your dwelling (flat or house) is in the southern half of the UK (i.e. South of Manchester) and that you set your thermostat to 20 °C. If you live between Manchester and Edinburgh, increase your estimate of heat pump power by 10%. For each 1 °C above 20 °C that you set your thermostat, increase your estimate of heat pump power by 10%.

Had noticed I haven't been billed yet since moving to Cosy, in mid July. I started to do something similar a couple of days ago, after finding I was taking in grid then an hour later the sun came out. So I have 3x charge slots in the afternoon 70, 75 and 90%.

That is not necessarily always true. You can take a common sense approach to air leakage. 1. Do you have open fire places? 2. Are rooms drafty, can you feel a breeze around closed doors, both internal and external. 3. What sort of build is the house. 4. @JamesPa favourite, what was or is your current operating regime for your heating system? What are your gas/oil usage. Use that to back check your likely heating requirements.

Sorry not read the thread - but an observation this is all G3 related stuff being discussed - should you have a G3 certificate to be playing with this?

About £6500 delivered in Feb 2023. https://gardenhouse24.co.uk/

Not sure BCO will give a monkeys. If the SAP report says you pass go, you are good to go. It's what the SAP assessor wants really. Mine wanted manufacturers calculations for U value for the whole window.

The kit was pretty easy overall, the additional insulation added a bit of complexity but it's very solid, pretty much keeps noise out, so quite overall. Only downside is overall airtightness. Better sliding doors would help. But at the end of the day with the dMEV fan ticking over, it's humidity stays nice and low. Heating - doing it again I would do a through wall Aircon unit for heat and cool, instead of tying into the house. The experimenter in me, would do a Larson strut if doing it again.

That was my thoughts also, one of the key selling points is you don't need steel, other than rebar. Other thought was why do you need an 8.4m wide opening. Other was this, for an 8.4m opening?

Not really you should have a 3 point actuator, so it will have power to move one direction and power to move another, plus it will need to read flow temperature

The word should is what makes people nervous, "should" and "is" are very different. Plus all the talk about fires starting from the MC4, it's more likely a "should" than "is", for safety. I prefer to be on the safe side and know when I come to pull the inverter, it can be completed without live high voltage DC kicking about.

To get a notification sent to someone type "@" and continue with no spaces to type the person's name. You will get a drop down list, choose the person - done. Comes up like this in the message @Nickfromwales

Couple of things to watch for. UFH works well with plenty of insulation and with zero insulation, but works very differently in both systems. Different flow temps are needed and different running regime. So don't let loops cross the two different floor build-ups, have dedicated loops in each section. You may want to to run two different manifolds and mixers for each section. They may need very different running temps. The zero insulation build up will require a very low and slow running regime, if you switch it off you will have reheat the whole sub floor each time, which will use loads of energy. The way to operate is to switch on at start of heating season and off at the end of the season. If you really don't want to do that install radiators.

Sorry have never bought in to that. The inverter DC isolator is fine for working on the PV array. But not fine to allow replacement of the inverter. You really need to be able to positively isolate the array, and AC sides to safely remove the inverter. I have 3 arrays and each has a dedicated DC isolator for the array as well as a DC isolator in the Inverter.

Limited head room already, I really would explore the big room feeling of a vaulted ceiling, will make your life so much easier, the additional headroom will make room feels way less cramped. Make a central flat section for running MVHR ducts.

By far the easiest is to put the insulation on top of the rafters, is that possible?

Looking at the drawing, not sure how you will be able to assemble without loads of joints. The material between the rafters will be fine, just a pain cutting. The under drawn sheets you will never get them in big sheets in place there isn't the space. Needs a bit of a constructability review

Depth for depth, done perfectly PIR on paper out performs mineral or natural wools and cellulose. But getting PIR to fit perfectly isn't the easiest job. So realistically natural or mineral wool may out perform PIR by a country mile. Plus there is decrement delay - how quickly the insulation allows heat to penetrate in to the room. The denser the better PIR is pretty rubbish.

Good luck cutting that straight and square. I would fill with cellulose or mineral wool. A drawings may assist visualisation. Why not make it vaulted?