MikeSharp01

I need to look at the Agile tariffs to help once I get it settled down and have the full BMS integration details. As it is I only have the read codes for the Modbus link. So although I can turn it on and off using the call for heat contact I cannot switch modes to DHW other than at the controller itself so not much good for the agile tariffs.

I think the 70T is the whole structure without the cladding or insulation. The slab is 100m2 at an average depth of 200mm so 20m3 of concrete. Which interestingly is what it says on the slab concrete bill IIRC. So 50T inc the steel or there abouts. Its been too hot in here for the last two days. I have added no heat in since the 10th and what with solar gain, high local temps, and me working at plaster boarding, the temperature today is 0.7 oC lower than it was on Tuesday when I turned it off. 19.9 when I turned the heat pump off and 19.2 now! Can I be impressed with that? The slab has lost 2oC over the same period and is now at 19.44oC so perhaps some charging will be needed as the whole house drops together.

Yes I get that and I was only Joking anyway. Yes I am being now as the house is too hot for heavy plaster boarding so I have left it off while I await the technical curve setting details. Even leaving it off is quite instructive though. the slab has lost 1 degree in 24 hours with an external temperature (OAT) of 10 degrees form 21.5 - 20.5 while over the same period the room temperature has dropped slightly less - could be because I was working in there today.

@Jeremy Harris played with those although I think he just used them to boost the hot water at the end of the HW run. I dimly recall he gave it his best shot but in the end removed them as they didn't meet his need.

Ours is 1.2kW at -3, half that is 600W is there such a Heat pump? - I think your latest goes down to 1kW, ours only goes down to 1.8kW. We are still a long way from COP of 6 although today I was playing again and I managed a short run at 5.

Whole house Audio one presumes, is that for making sure the same music is everywhere.

We are always interested on here. Sometimes driven by pure schadenfreude but mostly because we know we will go, or have already been, there.

Yes I recall now you mention it. To be fair the heat pump is, for the most part working well. The house is over warm now, so I have turned it off until I can get some more info from the manufacturer about controlling the curve. As it stands although I thought I had control of the two endpoints on the 'custom' curve I don't so I am awaiting an update on how to get control of it. I did think today, in the midst of my frustration with this, that now I have my MCS certificate I should just pop a Willis heater in to run it when the output required is less than the heat pump minima - how cheeky would that be?

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.

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.

We did have some sediment when we did the original pre commissioning wash through but not a great deal. I did that earlier this week first backwards, as you suggest, and then forwards. The flow rate was prodigious both ways at 12L but of course that was at 4 bar pressure, the pump measures just over 0.6 bar. I then ran Sentinel X800 for a couple of hours and flashed that out, then put X400 in and have left that to see if it can do any more. The long and the short of all this work, and taking out any Glycol, is that I have improved the flow rate a little in the long run and so across the UFH by, well, nothing really, about 30l/hr and most of that improvement is probably due to the higher flow temperature changing the viscosity of water (you can see the effect of this in chart below). Anyway I am not too downhearted because we have managed to find a stable operating point at COP of 4.0+ and got the house up to temperature. At the end of that group of runs the slab temperature reached 23.8 deg C and so turned it off because that is about what we want in the final event. Next week I will connect a slab temperature probe directly to the EMON so I can watch it all in one place. Zooming out to now you can see that the house temperature lags the slab by 7-8 hours! Obvs the period of inactivity hist the overall COP but I am not displeased by even that. I am not sure I need to reach for an industrial pump as I think @SimonD was correct in urging patience while the system settles down and I think we have clear evidence that approach worked here. One more thing I found when making adjustments is that the Control on IN / OUT switch actually refers to using external or internal sensor but has no effect, when set toe external, unless you also turn on Weather compensation. So where to from here is my next question. I need to either switch on weather compensation and see if I can tune that or run the UFH in much lower flow temperature chunks against a stat that could be room temperature but looking at it might usefully be slab temperature given the way the system (house / slab/ heat pump) performs although I am not sure.

Yes and perhaps the question is who supplies the gravy for this train.

Some might argue that although this appears to be the case in fact the real thing in the driving seat is perhaps vested interest, but once removed, so the vested interests that focus the governments interests. Long may it continue.

How did you control it.

How do you control it