I just sent the below note to Daikin, but does anyone here know the answer (or can point me to what I missed already here!)?
I have a Daikin Altherma 3 M (Monobloc) EDLA04E2V3.
I have been running it with a 5A continuous power limitation since May to keep demand well within what my Enphase battery can support when making DHW. That combination works exceptionally well and has allowed essentially zero grid consumption for DHW since then!
However, I would like the ability to have that 5A limit apply *only* for DHW, or *not* to apply during defrost.
I today disabled the 5A limit to avoid conflicting with the wording in P685228-1B 2023.05 “Set a minimum power consumption of 3.6kW to guarantee … Defrost operation.”
Can the firmware be upgraded to allow this finer limit control, please?
This feature is not available in the existing system, and there are no planned updates in our current roadmap to enable this functionality.
We truly appreciate your innovative approach to optimizing your system and your valuable feedback. I’ve passed your suggestion to our product engineering team for consideration in future developments.
There is a Demand PCB (EKRP1AHTA) which has 4 digital inputs which expands the single power limitation to 4 different levels of power limitation depending which of the 4 digital inputs is toggled. It would require a little bit of external control to make it work but would do what you want. I wonder whether one of the inputs could be tied to the 3 way valve switching to DHW for example. Its detailed in section section 6.6.2 of the installers manual.
There’s also the Smart Grid module which is intended to be connected to an electricity meter to match heat pump input with solar production, this could also be manipulated to do what you want. Again still needing some external control. Section 9.2.14 of the installers manual for this one.
I can see the issue with substantially limiting input power being an issue during defrosts. This will also apply during DHW production won’t it?
Yes, thanks, and I have considered going the whole MODBUS card route to get more data and control also.
And this almost could just be something local in the outside unit that if the outside temperature is >~10C (so no danger of frosting up) impose the lower limit.
The 5A limit worked fine for DHW from May until now, smearing demand nicely, and allowing my older grid-coupled battery to cover it entirely, and merely slowing generation of DHW a bit.
I’ve been running my 9kW Daikin with power limitation, for several reasons: to try and keep under battery power limit, reduce noise, and to ‘tame’ the beast
I typically run with an 8A or 9A power limit. I did find during the cold snap last January that the heat pump wasn’t able to hit the target flow temperatures between defrosts. So I upped the limit to 10A and that was enough.
Interesting thank you! My battery’s maximum power output is ~1300W/5A, so setting to 10A would at most guarantee about 50% of DHW heating in summer (before the first user gets up) covered from our own solar/battery.
Did you find any problems with defrost failing with an 8A limit? I want to avoid a frozen/split heat-exchanger! Discomfort is easier to work round, and our 4kW limit is about twice our ~2kW peak space-heat demand, which probably only needs about 1kW in to cover.
(My model is the 4kWh/6kWh/8kWh, so may be substantially different to yours on this point, of course, but still … data points!)
If you look at defrost cycles on heatpumpmonitor, I don’t think they need a lot of input electrical energy. As far as I understand it, the defrost cycles involve pumping the already warm water back through the heat pump to extract heat from it to defrost the condenser.
Similarly, the anti-freeze protection just circulates water around the system. (I have both booster and back-up heater disabled.)
I think my experiments showed a current limit of 6A was too low for my 9kW unit to get up to useful temperatures in cold-ish weather. And at some current limit (4A or 5A maybe) the compressor wouldn’t even activate.
Of course if you are worried, you should operate the heat pump in accordance with the manual.
