I’m still getting to know my Daikin, and experimenting with the various parameters. One thing that’s confusing me is that it’s continuing to heat despite already being at the target room temperature.
I’ve been using the cloud API to get stats for now…
(The power measurement is coming from one of Zappi’s CT clamps.)
So despite reaching target room temperature of 20.5 by 10:47 am, it continued heating all day until I intervened and turned down target temperature at 15:48
At 11:17 the power of 112 means condenser was off and it was just the pump - lwt=42 must be the max - but it still started heating again as soon as the water had cooled down.
I do have a relatively high modulation (8) and overshoot of 4 - I’ve been trying to find best way to get it to warm up overnight during cheap rate.
If you have set 20.5c it will heat until the room gets to 21c (0.5c above set) and come back on at 19c (1.5c below set), Maybe just 0.1c to go as it was already at 21c at 14.38
The heat pump probably turned off the compressor at 42c because it exceeded the set lwt by 0.5c plus the 4c overshoot.
And later at 40c.
I guess you have a wdc and it was getting warmer outside so the request lwt went down?
Ah, okay, that explains that. I do find it a bit annoying that the schedule only allows setting whole degrees, even though the Madoka can set the target temperature to half-degrees (and can report it to 0.1 resolution).
In principle, if the weather curve could be set accurately enough, it would just sit at 20.5 without actually going above.
yes, weather curve would have set it to 34, I think, and overshoot is 4. And I also have the lwt offset set to 3 (because, as I said, I’m experimenting with parameters). So that would make 41 the max.
Yes, though the description in Daikin Monobloc Heat Pump - User guide - #4 by Arnold suggests that it doesn’t anything until it more than 0.5 degrees away from the target temperature. Maybe it’s a bit more finegrained…
I don’t use HA. By Onecta integration, is that the one that uses the cloud api, rather than p1p2 or espaltherma. I am using the cloud API, just through python scripting, but I’ve not immediately seen a way to set the lwt adjustment via the API.
What I was thinking was to just set a high target temperture, and that should get the modulation to provide the necessary increase to the lwt. (And that has the advantage of happening locally, rather than requiring that the network is actually working to send a config change through the API.)
I think this is the other way around (with regards to the hysteresis amounts above and below target). It’ll come on when 0.5C below target and will stay on until 1.5C above target.
E.g. my target temperature is 20C, the heat pump will begin heating when the Madoka is reading 19.5C and will continue until 21.5C.
I’ve actually got Home Assistant to intervene because the 1.5C above target seems like an unnecessary use of energy to me (especially when raising the temperature by 1C takes a loooong time at low flow temperatures), so I have an automation that’ll turn off heating when the Madoka is 0.5C above target.
Interesting… I had been thinking that 1.5 degrees was a long way to fall before turning the heating back on.
It’s also a very significant overshoot while heating. Though if the weather curve is set up just right, you want to remain on, emitting heat at just the right amount level to maintain the target temperature without actually increasing it. And has mentioned, if it does drift up, modulation should kick in an reduce the lwt.
In an ideal world, you don’t actually want the thermostat to have to step in to turn off the heating. (My room temperature was rising because I’m still messing with the lwt settings while discovering how the various parameters interact.)
I wonder if there’s merit in using the automation to adjust the lwt offset down, rather than actually turning off the heating ? ie doing what the modulation could/should be doing. Could possibly step in when room temperature has drifted only slightly away from target.
Actually room temperature modulation does already step LWT down if room temperature is 20 minutes above target (and steps LWT down more if 0.5C above target). However when LWT is lowered, this may trigger an LWT overshoot, so to avoid overshoot you may want to allowed a maximum overshoot of preferably 4C (and for hybrid systems this is unfortunately not possible as it is fixed to be 1C).
The problem with the Daikin Altherma’s is they can’t modulate to particularly low temperatures and, especially during these shoulder months with outside temps between 8C-15C, my flow is already as low as it can go. Also the lowest energy draw my 6kW Altherma can run at is ~350W (I know the 9-16kW has a much higher minimum draw, somewhere around 900W!!!), so having the system run for additional hours is not an insignificant use of energy.
I’m aware that the wisdom is to run the heat pump continuously but I think that is the wisdom for achieving highest COP, not necessarily the wisdom for lowest running cost. Have a look at all the Daikin’s over the last 90 days on heatpumpmonitor.org ordered by running cost and I’m top of that chart whilst keeping an always warm home and abundant hot water for a 4 person household.
