No problem, I’ll answer what I can.
I’m not 100% confident that my energy monitor is accurate. It is supposed to be pre calibrated, but it could be under reporting. I’ll get my alternate clamp meter up and running to compare tomorrow hopefully.
I wasn’t aware of the preheating thing, I can’t explain it. Can you show me an example of a system preheating?
I haven’t done anything very much different to you two I don’t think. I set underfloor heating to get DT3 and the ability to set overshoot to 2. I started out with a leaving water temp of 26 to dial in the curve and use home assistant to adjust the offset up and down. Currently the daytime offset is +5 and night time +4.
Whilst Octopus changed ten of thirteen radiators from type 11 to 22, I was able to swap the remaining three and bumped two up from their original size (type 21 to 22 and type 22 to 33). I’ve also balanced them properly. Total output before the last three were swapped was 7556W. edit I think that’s at DT26.5 or whatever Octopus use, it’s what’s printed on the radiator schedule
My radiator schedule shows a design temp of 50 degrees at -2.2 but I’m sure their air change calculation is way off. Other than the cat flap the house is draught free and decently insulated. Cavity insulation was increased on April 17th from a partial fill to a full fill.
My flow and return pipework is quite lengthy, I suspect when it gets colder I’m losing heat there. Perhaps that explains why when it gets colder performance drops quite a bit.
My heat loss could be wrong, one of the plumbers told me and it was either 5.6 or 6.5 I forget exactly. I’ve adjusted to 6 for now to avoid confusion and checked the data issue flag until I confirmed power usage.
I have a volumiser in the loft, the standard 20L Octopus one. edit I’ve removed buffer from my profile and left volumiser checked.
BTW Matt I read through your giant thread when you had issues with the 9kW unit. I was also supposed to get the volcano unit originally and managed to convince Octopus to fit the 8kW unit without any pushback. Many thanks!