Idle consumption?

[muryoh]

Hi there!

I'm wondering if anybody's seeing the same idle consumption?

That's a 14kw R32 unit - not sure if the consumption would be lower with a smaller one

1.8kwh per day seems crazy to me - I've tried looking this up, people seem to mention a heater in the outside unit to make sure the oil stays warm enough...

Is there data I could confirm this with in any of the existing sensors?
What do you guys do about it in summer?
I imagine for somebody not having DHW, they'd probably shut it down
But with DHW this idle comsumption seems quite unreasonable 🤔

I was wondering how safe/healthy it would be to turn it off outside of DHW cycles

[gekkekoe]

it's 'normal'. How do you measure consumption? The reported daily numbers by the heatpump itself can be a bit off. You really need to split the consumption based on the operating mode. I am seeing around 0.5kWh - 0.8kWh a day.

I just leave it on, since it's such a small portion (using cooling/heating/dhw).

[bwduncan]

I'm looking at ~0.6 kWh a day, measured with an SDM630, on days when everything is prohibited (I'm a very light DHW user). It's a bit frustrating, I don't understand why it needs to spend £40 a year to do nothing. If the electricity price goes silly high (>£0.50/kWh) then I do turn it off, but it's a major pain, and in the summer when I'm hardly using it, the consumption is free because I have solar PV, so no, only rarely.

Obviously the thing is designed to survive a blackout, it's safe to turn it off, but I wouldn't leave it turned off if it's at risk of freezing. That's going to cost a lot more than 10p/day.

[RSDynamics]

I found a workaround for the high idle consumption.
In our case the idle draw is about 10W measured with a Shelly EM.
When you power down using the switch in home assistant, after about 15 minutes the idle power drops to around 3W.
At that moment you can turn on the heat pump again and the idle power stays around 3W.
Of course I have an automation that handles that for me.

I don't think our unit has crank case heating so it seems some sort of bug in the FTC firmware. I have not found any reason for the higher consumption.

[gekkekoe]

The power inverters do have crank case heating. But I would expect that they also need to apply heating for SUZ units. The SUZ manual does mention:

1.4. Before starting the test run
Caution:
• Turn on the main power switch of the outdoor unit more than 12 hours
before starting operation. Starting operation immediately after turning on
the power switch can severely damage the internal parts. Keep the main
power switch turned on during the operation period.

This implies that some heating is needed and that you should not do cold starts. You can achieve more meaningful optimizations than these micro optimizations that could be harmful

Also, every power cycle puts stress on your PCB and components in the outdoor unit and probably will cause premature wear. I would just leave it on as the manufacture intended it to be used.

[muryoh]

Unfortunately so far I've only been relying on the heat pump internal reporting
I hope they're off by more than just a bit - the numbers seem crazy to me: some days it goes up to 2.8kWh, with no DHW cycle!
I do agree with your analysis though, it seems risky to just shut the heat pump down everyday to save a bit of electricity. I'm just really surprised by the numbers I'm seeing. Ideally I'd use actual on wire monitoring but that seemed a bit expensive and was hoping this would be reliable enough

[gekkekoe]

The internal reporting is an estimation if there's not a pulse meter wired into it. They also like to add the idle time to the operating mode. So probably it estimates 2.8kWh for dhw today without dhw.

But it's can be quite off, my numbers (energy meter) and @bwduncan seems reliable.