Posted by: @tasos

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Is the WC "tweaked" ?. Because that would explain this behavior. 

No. My auto-adapt script (tweaks WC end points based on actual vs desired IAT) logs its activities, and, looking at the log, no changes to the WC were made at or around that time. That also fits with the IAT on the chart, steady and where it should be, at 19 degrees.

Posted by: @cathoderay

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Posted by: @tasos

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Is the WC "tweaked" ?. Because that would explain this behavior. 

That also fits with the IAT on the chart, steady and where it should be, at 19 degrees.

I am really surprised that the IAT is steady, whereas LWT is fluctuating a lot. How can this be ?

Posted by: @tasos

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I am really surprised that the IAT is steady, whereas LWT is fluctuating a lot. How can this be ?

High thermal mass, plus that chart is very zoomed in. If you look at the 48 hour chart (the one with the compressor frequency on it) you will see the IAT did fall as the defrost cycles degraded performance at close to design conditions (-2 OAT). Also note this period was before 'big bang' on 25th Jan 2025, when I opened all the lock shield valves as far as I could (plenty of documentation in other past posts). Before big bang, my heat pump did fail to maintain the IAT in cold outside conditions.   

Thanks- interesting and useful observations and I did notice that the set LWT was pretty much the line of best fit, so to speak, through the oscillations.

I do find myself wondering what I did with all my time before I started studying my heat pump graphs on a daily basis.... 🤣 

@cathoderay I was also sceptical but my installer was very keen to integrate a Homely onto my 16kW gen 6 Samsung. I have to say I’m loving it so far, it runs my  (probably oversized by at least 2kW) ASHP extremely leanly, the flow temp is 25C at the moment and modulates down to 0.6 kW input as measured by both the heat pump and Tesla PW3. It maintains the room that the hub is installed in to within 0.2 and 0.5 C of my target temp and immediately reacts to any solar gain. Getting a monthly COP of 4.9 so far in September. So easy to use, I have to do nothing at all. I don’t run on smart+ mode as it’s being powered through the home battery,Tesla (and net zero app does the clever stuff to maintain the battery permanently charged with the cheapest possible power through a TOU tariff.
I would like to see the data, but I can see the power used through my Tesla app, so I know what it’s doing wrt to power anyway. I’ve registered as an installer, so can get the data if needed, but not seeing any value in doing so at the moment. I’ve also compared it to the systems on heat pump monitor and it’s outperforming those by a considerable margin. 
So far, very impressed at its performance and ease of use and I’m not even on its subscription service. 

Posted by: @papahuhu

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So far, very impressed at its performance and ease of use and I’m not even on its subscription service. 

Thanks for the feedback, we do like to present a balanced view here on RHH! I am glad to hear it works well for you. Maybe report back after a period of cold weather? 

Will do, I nearly refused to get it as I’d picked up on so much negativity. if it plays me up it’s getting turned off immediately and I will dial in my own weather comp. But so far, my cycles are longer and my flow temps lower than those on heat pump monitor, so I’m taking that as an effort free win. We are in a house that all the big installers refused to touch without switching to 3P, nearly 300m2 and 25 rads, all but 3 were changed out. 

The installer has commissioned dozens and swears by them, I carefully “supervised” the install and it really was a case of plug and play, very easy for them and couldn’t be any simpler for me. It’s akin to having a dial thermostat with a timer on the wall, but on my phone.

@papahuhu I too have Homely control but do not use Smart+ thus do not use the subscription service. In fact I found the Smart+ tended to lose some control of the comfort level as it always endeavoured to maintain the HIGHEST set temperature despite other settings requiring lower temperatures. I note you are using NetZero with your Tesla setup, are you on their subscription service for this and do you feel the extra cost pays for itself? Regards, Toodles.

@papahuhu quite normal to get a cop of high 4s in September. Nothing outstanding that homely is doing there.

At the moment without homely ours is above 5. Homely same time last year was achieving around 4.8 to 4.9 so a tiny bit lower.

Of course this is only one measure of performance, and early days for us testing without it. 

Agree that homely is effort free, and app controls are decent.

@toodles 

Although I’m still connected with net zero it’s not strictly true that it’s currently managing my battery. I haven’t run agile for a while so it wasn’t necessary to pay the net zero subscription. The PW3 management controls are a bit clunky as what the Tesla  AI considers correct doesn’t always correlate with what I consider to be in my financial best interests, but if you significantly exaggerate the tariff structure I can get it to discharge and charge when I want it to and according to a fixed TOU tariff.
I’m in a dilemma at the moment, last week I switched to Cosy (from intelligent flux)  as I figured a guaranteed 13p Kw, three times a day, together with my 14ish kW of storage would get me through cold spells on off peak rates. However, this morning, octopus mailed me that they are increasing prices to 15p/kWh in October. I suspect my heat pump will chew through 50-70kWh a day when it’s very cold, we are up in the hills in the Peak District and it gets a bit fresh. 

So, I’m reconsidering agile again. I may hold my nose and pay monthly net zero subs for peak heating months of Dec, Jan and Feb. That also coincides with my minimum PV output so I will get the maximum gain. By end of March I’ll be back on intelligent flux (or the new Tesla power offering). 

@benson 

Possibly but when I looked on heat pump monitor the highest performing identical unit was running a COP of 3.5 for the same period. I was just comparing like for like as that’s all I can do. I’m only running an old generation Samsung as it was cheap. Time will tell, but my original concerns from reading all the negativity have not been realised, yet! I’ll get ready to eat my hat. 

Just come across this video on youtube

We have all radiators/no UFH. It isn't clear whether this setting would be beneficial with rads when on occasion set flow temps are under 35. Anyone able to advise at all?