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This could just be the shift settings need adjusting but at the moment, if you've got min set to 28 and max at 32, your curve is definitely too flat. What's the calculated flow temp and min outdoor air temp? And what is your calculated heat loss at this temp? You can simply calculate your heat co-efficient W/K to establish a baseline curve at all relevant temps.

Cheers, I’ve got more in now (but only 5 per length) only put three in last night as I thought the neighbours might not enjoy the impact wrench! also glued with expanding glue. I’ll either bang some more in or get some nut and bolts in aswell before I get the sheets down. thanks all

You can work it out knowing your heat loss and then W/m² Just use this as a baseline, you may need to extend the W/m² and the MWT - mid way between flow and return temperature.

Yes. I have now turned it off to let it settle and then tomorrow I will set much lower points and I was wondering if I had the numbers too high perhaps even the wrong way around because there is a hint the heat goes up when the temperature goes up but that may just be surmise as finding those set point parameters was somewhat guess work.

My two cents worth: I've been comparing ASHP specifications for far too long in the process of making a choice for my build. One of my criteria is the quality of the manuals and NIBE are good in this area. As mentioned, a lot of manufacturers don't give much info about the minimum outputs, but this data is in the NIBE installation manual (at least for the F2050 that I was looking at). My concern about the NIBE was that it doesn't seem very DIY-friendly. It can obviously do everything (smart grid, inverter integration, machine learning, integration with MVHR) but only if you have a compatible inverter, MVHR and a bunch of NIBE smart controls. I prefer systems that support a more open approach e.g. modbus or volt-free contacts to control these functions, but that may not be relevant for everyone.

Looking at room temperature the line is steady climb, which is good, but suspect your flow temperature is way to high. A 2 Deg rise over 12 hrs is very fast for thick screed. Your +15 degs I would be setting sub 25, maybe 20 to 23, your -5, 28 to 30. Start low, and move up. A hot house is a horrible place to be, especially when it's a thick floor and it doesn't cool for an absolute age. At 10 degs your house will not need or very unlikely to need heating, when dried out. Your running 30 degs, that is nearer what you will need at -5.

Yeh i think my last place had poor form factor it was a T shape and a bungalow. Also the cold bridge at truss to wall wasn't great as didn't go with eco trusses so insulation was quite tight here. Air tightness was great but mvhr was over ventilating I did diy commission then paid for someone reccomend by bpc to commission, they were clueless. Anyway forgetting windows for now because I'm just looking at whether its worth increasing insulation width. I don't think it is.

Some interesting diagrams. First from UK gov https://assets.publishing.service.gov.uk/media/6887aa04be2291b14d11b01d/Energy_Flow_Chart_TWh_2024.pdf And Lawrence Livermore labs. Some notes - the UK gov is 2024, LLL is 2017. The LLL diagram use Peta Joules whilst UK uses TWh Conversion is 1,000 Pj is 278Twh The reason I included the LLL diagram is that it shows wasted energy (heat) And the crucial bit is the useful energy for the UK is around 2,800Pj or 775Twh. A lot of people concentrate on the left side of the diagram, primary energy which is somewhere around the 2,000Twh of fossil fuels at the moment (the diagrams don't match up exactly so that is a round number) That is around 20x our current renewables - so people rightly say "hang on a minute, we have to build another 20x wind turbines, solar parks etc.? That seems alot....." But renewables don't have as much inefficency so we should be looking at the 7-800Twh useful work. For example transport uses ~650Twh of delivered energy (primarily petrol/diesel) but only around 140Twh is actually used - the rest is heat. So if we could double our current renewables (+100Twh) we could replace about 2/3 of the petrol and diesel we use. Domestic heating uses around 275Twh useful. If we used heatpumps with an achievable 2.75 SCoP we could replace the vast majority of domestic heating with another 100Twh of renewables. So we could replace 2/3 of our petro/diesel and almost all of our gas heating by 3x our current capacity - not impossible.

Nibe (and others) use an energy integral, so if they are cycling they use a fancy time, to degrees of heat delivered calculation, so they can provide a higher than target temperature, to get a decent run cycle and time off, while still managing the energy delivery to house. Basically ensure short cycling is never an issue and energy delivery is on target.

Ok I have set up Weather compensation on the CE-iH6+ heat pump with its Carel controller using the Huilian App. It's a bit of a faff because the manual does make it clear what the various settings are that control that start the end points of the curve (line). Getting ChatGPT and CoPilot (I like to use both so they check each others work!) to hunt around and a bit of experimenting it all became bit clearer. It is clear that two of the values are fixed - you can do nothing about them in this system. The minimum Outside Air Temperature (OAT) is fixed at -5 oC the Maximum OAT is fixed at +15 oC. The curve runs between these two values in X and you can set the Y values as flow temperatures for them both. So for anyone who is using this same heat pump: To set a custom curve (one you can play with flatten / lift / drop) you need to select Curve 9 in the User Para menu via the Huilian App. Then for the top of the curve, lowest Outside Air Temperature (OAT) which is fixed at -5oC, flow setpoint you use "Heat Set temp" parameter and I set mine to 32oC and for the lower setpoint (OAT fixed at +15OC) you actually use the "Auto set temp" parameter and I set mine to 28oC. The Graph is interesting on a number of fronts. The heat pump has been running all day - no cycling or defrosting, although as you can see as I took this screenshot things are happening! I will take a look when I have finished this post. Over the day it has been modulating down the output and the COP has not been bad. The Delta T is now under 5 (approaching 3 at the very end - which is thumping the COP) and the slab temperature (not on the graph has climbed from 19.62 to 23.31oC so a bit further to go and we will hit the hard limit on the slab temperature. Not that I have implemented the stat for that as not sure how best to do it I will just turn the thing off. The best thing today has been the sun shine so for most of the daylight hours we were getting all the heat for free! Perhaps the worst is that looking at how the house performs I really need a much smaller heat pump, might have to think about following in @JohnMos steps. Finally looking at the very end it looks like, for some reason (I have not changed anything), it has jumped (modulated) the output down to 2.6kW and is running it down more slowly from there. Minimum we can go is 1.8kW on this unit! It must give up eventually trying to limbo under the wire. At which point it will go into short cycling. Need to get the BMS connection up and running so I can get some more intelligence into it from there.

Your form factor is good, it's a rectangular box. So U value effect is different from a poor form factor (like our house). I would look at a slight bigger scale than just the walls, so floor windows/doors and roof. Get a bigger picture. Note: Passivhaus required U value changes with form factor.

Yes, thanks to this group, this is almost my first question to the supplier. If I’d became clear they didn’t understand modulation (some didn’t), then they ruled themselves out. The Nibe I’m considering does have good low level modulation.

Was weighing up this choice recently leaning towards 200mm cavity. I've built last 2 houses at 150mm. I plumbed the numbers into Google AI just to see what it thought on a 8x11m box 2 storey house. If the info it gave me back is right then I'd probably stick at 150mm. I thought it wouldn't be too much dearer but I think things will add up. I do remember someone @Mr Punter? Saying it was best to internally insulate the additional 50mm to keep everything more standard, footing width, ties, closers, lintels etc. The energy savings just don't seem worth it 50+ year payback and if you are constrained on overall size of dwelling your losing 2 or 3% in net floorspace. Anyone else make this decision and why?

Less romantic, but I’m a married man so will take whatever I can get 😜

Plus, Im more of a Laurel and Hardy theme type of guy.

Where’s your sense of adventure? And anyway, I’ve got a multi tool and a lump hammer, so what could go wrong? (Opens window for small Screwfix order…..)

Only with consent, or a face mask and rubber suit, don't want to leave 'evidence'.

Well, this is just plainly naive, isn't it? What about all the infrastructure and energy required to run all the cloud functionality? That is a really good point and one I have not thought about. A very quick web search seems to show that 1 TB of data uses between 40 and 70 kWh/year. If each 'user' has 1 GB of data, that is around 0.055 kWh/user.year, or 6W. A Raspberry Pi, running headless uses about 3 W, with a bit of tuning, about a watt (what mine uses. An ESP**** about a tenth of that. To that figure, the energy usage of 'smart switches' needs to be added, regardless of if it is cloud or locally connected. Another quick web search gives a result of 1W for a Shelly Relay. So that could be another 10W for a few connected devises, or ~90 kWh/year. With a cloud connected service, the energy usage of the data transport has to be taken into account. So a local router, a share of the local telephone exchange (or 4/5G), 3 to five internet servers etc. So it is probably cheaper to use a local service, that is hard wired if possible, but not as good as a manual switch. Food for thought.

I say look at modulation - can it run all day long at most weathers? As in not cycle?

We had to go and poke the sleeping bear with a filthy stick now, didn’t we…..

Hold that thought for a moment, and get 1x of that fitting and see if the plastic centre will go into the 15mm compression connection, and THEN we can pucker up. I’m thinking Officer and a Gentleman theme playing in the background for completeness.

Any drawings of your roof and wall interface? If it's complex then I would recommend moving your airtight layer outboard of the rafters.

(expletive deleted)ing ? pricking ? sucking ? mofo ing ?

Yeah that’s all wank . The entire point of automation is you don’t do anything .So lights / heating etc come on automatically. 1 button push ( SWMBO friendly ) causes ust projector to come on , shelf slides out , amp turns on , 120” ( I’m big ) screen goes up and the pants ( blinds ) come down . User interface if you must have one must be simple and intuitive - anything other is poor design . You should see what I’m working on ….. people need simplicity even if under the hood it’s a bitch . Anyone care to look under my hood 😉

We’d have a very comprehensive and long thread….if it was tilted “future planning of heating now for, but must also encompass foresight for future moving or removing of walls, and its downstream impact…..”. yes, I’m a pedantic tosser. I’ve already been and grabbed my coat.