Hey ​@AliSmi,

I’ll tag a few of our heat pump users to see if they can offer some advice! 

​@juliamc, ​@nealmurphy & ​@Peter E do you have any suggestions or insight you can help with?

I'm not an expert on ASHP and the hysteresis setting but my best guess is that it prevents excessive cycling of the unit which would otherwise significantly reduce the efficiency of the unit with start up periods.

I need to ask why you need to change the hysteresis. Is it because that the house is getting alternately too cold and too hot at times? If that's the case then maybe reducing the hysteresis will stop that without the ASHP cycling too much when the house is presenting a much bigger load on the unit.

It's only a guess. I'll see if there is anything I can find out on that

Peter

Not sure I can help - I don’t set hysteresis on the Daikin except for hot water reheat. It could be an installer setting, but not one I know about.

Thank you both for taking a look anyway! ​@Peter E ​@juliamc 

​@AliSmi I came across this thread on another Forum which might help - https://forum.buildhub.org.uk/topic/37184-best-thermostat-hysteresis-for-ashp/ from what I understand from it having a smaller hysterisis would cause your system to run more often to maintain temperatures. 

Thanks all for coming back to me and ​@Chris_OVO for the link, I’ll continue to investigate.

FYI ​@Peter E the house temp is fine so there aren’t any issues per se, its just when it’s this cold (and w/ a hysteresis setting of 0.2 degree, if the temp is set to 20, and 19.8 the heating will start heating again, however in these temps the house temp will often drop another 0.1 (before the heating has had any impact on the house temp) so it needs to heat 0.3 degree rather than 0.2 which takes longer