Very likely, yes. Or more specifically, the heat pump is too large for the emitters you have. Ensuring you have as many radiators open as possible will help. I’m not sure balancing will necessarily improve things, unless there are a couple rads short-circuiting hot water to the return. Restricting lock shield valves too much could have a negative effect.
There is an optimal flow temperature for your system where your heat pump will settle into a steady state, when the radiators can emit the heat that the heat pump is producing. The more (bigger) radiators you have, the lower that flow temperature will be, and better performance.
These are the settings that can influence Auto Adapt:
Dropping the Lower limit and/or increasing the Interval can increase the time between cycles, allowing the system to cool down some more and potentially perform better. Probably not enough to make a big difference, TBQHWY.
My own 11.2 kW system (link in bio) also has a minimum flow temperature of about 40°C.
Just a quick reply without looking in any depth… I guess you have a fixed-speed circ pump. (not one that adapts to dt), so the dt will vary with heat-ouput power. Its normal, and not a problem. The rev-up is annoying isnt it? why speed up so much, then stop, then re-start so quickly after. What model is this? I think Mitsi realise they set the algorythm with too much ‘panic’ for adequate heat, with not enough concern for running costs. This should be able to run in a steady state.
I have been experimenting with controlling the pump to try and achieve a constant dT but very early in the tuning of the PID controller. That’s why I was experimenting with Weather Comp again.
You’d think the ramp up at the end of the cycle could be beneficial in increasing the gap between cycles a bit but doesn’t appear to do that.
It’s a pitty there doesn’t appear to be software updates to refine the algorithm.
I still don’t really get why the heat output is low to start with then suddenly jumps, it doesn’t look like the return is going up just that the flow temperature starts ramping up. Seems to happen before the HP decides to up the input power.
I keep coming back to a thought about how the flow and return temperature sensors connected to the FTC would effect performance / behaviour of the system (in my general clutching at straws to try and explain the difference in performance of different Ecodans).
ASAIK the thing the controller is controlling is the flow temperature from the outdoor unit, and also maybe the dT between that and the return? If so the temperature sensor placement and how they are installed could be very significant.
So I’m wondering if in systems like mine, @Timbones’s and others, where the outdoor unit is quite a distance from these sensors whether the lag in temperature measured on the flow when the compressor modulates and the potential heat loss between the return and flow sensors could have an impact on how the algorithm used by the controller acts and reacts to changes.
If there is significant heat loss from the pipes between the sensors the unit will also potentially be measuring a different dT to that at the outdoor unit.
I might be wasting my time thinking about this as the controller might account for variation in the position of these sensors in the system and might react to these readings slow enough that it isn’t an issue.
My sensors are probably around 8m of pipe away from the outdoor unit. I believe @Timbones yours is about 10m away.
I think the distance isnt a problem. Surely Mitsi have thought of this, and they dont specify a distance restricion. I recall seeing one at a great distance, and no obvious control diffrence.
My old 2009 ecodan (fitted on a friends house) seems steady as a rock, and i do feel that in trying to ‘improve’ things, in certain conditions, there seems to be problems. I will be meeting Mitsi in a couple of weeks, and yours is actually a good example for me to discuss with them.
Oh excellent, good to hear they are engaging.
Let me know if you need any information about my system or if it would be useful for me to try any settings to get data to show them.
My DHW woes (where heat output collapses but while the compressor still draws power before having to resort to immersion) have come back again now that it has gotten a bit colder at night again. I have it in Eco hot water mode that I don’t think helps. I did raise a ticket with them about it and after we ruled out flow rate haven’t heard back again.
I’ve always had the black SD card icon with white letters, indicating abnormal behaviour, rather than the white one with black letters indicating normal behaviour.
I replaced my SD card on Wednesday and the icon has gone white. Will see if AA gets better at adapting using a longer history.
