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Are the multiple and frequent changes in power input to a heat-pump considered to be detrimental to compressor longevity????
I assume it is due to the control electronics trying to do it's thing in these shoulder months. I'm plotting it via a Shelly EM on the mains supply to a Daikin 6kw on pure weather compensation.
I wonder if this represents cycling, and if so how long the cycles are. But I don't see cycles on the water temperature curves, so that's strange. Although it probably reports temperatures with 1°C precision so something could be hidden in the rounding error.
That could also be a sensor bug causing bogus power readings.
Can you zoom in on this mess? Screenshots are free, you can post several at various levels of zoom, so we can see what patterns hide in that solid block of blue.
Leaving water temperature is on the plot, can you add HP water return temperatures please. This way we can see if it is producing heat.
We recently had the 8kw Daikin installed and this was on my radar after watching my shelly data (way too much 😆).
I have observed similar behaviour.
As far as I can tell we have had very little cycling in the 6 weeks it's been installed.
However I have noticed the power consumption fluctuates by quite an amount. It never sits at steady(Ish) rate.
Ours seems to fluctuate by about 50% most of the time.
For example today the HP would consume around 250W for about 30-40 seconds, then creep up to about 400W for a similar amount of time then creep back down to 250W. This behaviour seems to happen all the time.
Only on a handful of times have I seen the HP shut down (I assume this is classed as cycling), drawing around 40w as the pump circulates the system.
I have wondered if this normal behaviour, or a sign that the system isn't as optimised as it could be.
I am running on pure weather compensation and underfloor heating setting with a delta of 5 (even though we only have radiators).
I have tried the fancoil setting and this fluctuating behaviour was the same.
@bash Hello, we have a Daikin EDLA08 monobloc controlled via a Homely smart controller; I am attaching a plot of today’s power consumption so far. I don’t know if this will assist or not but, for what it is worth…
Regards, Toodles.
Toodles, heats his home with cold draughts and cooks food with magnets.
@bash Hello, we have a Daikin EDLA08 monobloc controlled via a Homely smart controller; I am attaching a plot of today’s power consumption so far. I don’t know if this will assist or not but, for what it is worth…
Regards, Toodles.
Thanks Toodles,
This is very similar to what I can see in our Shelly app, however the original poster (and me) are looking at the real time data, which updates every few seconds. This shows how the HP electricity consumption fluctuates quite a lot.
When averaged out over an hour it is unnoticeable, so you have to look at the real time data as it updates every few seconds to see what is happening.
Do you have access to the real time consumption data so can watch how it changes in real time?
@bash Sorry, no, no Shelley, no higher resolution plots available (as far as I know) so apart from what I can see on my Tesla app when it fluctuates every ten seconds, I have no further details. Regards, Toodles.
Toodles, heats his home with cold draughts and cooks food with magnets.
Thanks. I suspect this is normal behaviour, so not particularly worried, but you never know with these heat pumps as there are so many settings and variables!
So on this question of compressor longevity, I have a Daikin Altherma 3 11kw installed by Octopus and I found that when the weather was a bit warmer the other day, but cold over night, that the blue light on the MMI kept going out and the power consumption of the heat pump dropped from c.1kwh to a few hundred w/h. I could hear water circulating, but when I went out to the heat pump, it was silent/the fan wasn't running. This persisted for about five minutes before the blue light came on again and the power consumption increased to c.1kwh. The pump is set to run using weather compensation (fairly optimised), but also using the temperature setting on the Madoka thermostat. The modulation was at 5 degrees and the overshoot was set at 2 degrees. I asked Octopus whether the compressor had stopped when the blue light went off as I was concerned about it's longevity and why the heat pump had shut down. Their answer was to recommend increasing the overshoot to 4 degrees. I have tried this and the heat pump still doesn't significantly overshoot the set temperature. My questions are as follows:
Am I right in thinking that the compressor has shut down when the blue light on the Madoka goes out and this is a bad thing?
If the heat pump knows what it's target temperature is and it has scope with the modulation and overshoot settings to adjust, why isn't it doing so?
