I’d love to know what is going on here. Noticed it a bit more recently, about 15 minutes before a hot water cycle, there’s a little spike in the circulation pump for 30 seconds… Only noticed it because the Mrs said the radiator in the bathroom (smallest in the house) was warm… I almost couldn’t believe that the pump running for barely a minute would do this.
the pump operates every 23-24 hours for 30 seconds to prevent seizing when not in operation for 23-24 hours
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Ah great to know… I’m guessing that’s a setting somewhere…
I’ve seen no setting for that
Same for my gaz boiler
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Thanks - now I’m looking back at recent days and weeks, on the days after a DHW cycle that only runs for 45minutes, a pump does the 24 hour anti-seize run. Whereas on the days when it goes for over an hour, the following day doesn’t have one.
German engeneering 
Very clever
I have let my heatpump decide for itself as to whether it needs to run or not over the summer. It has kicked in the odd day here and there, which is better than the years of the gas boiler and having the house feel slightly chilly the very odd day. It’s great now that it is all just automatic
Periodically but almost randomly my aroTHERM+ 5kW seems to cycle or circulate briefly (perhaps 20 mins) then stop. It’s been doing this for months or more. No errors being reported. I have HA logging data from ebusd which picks up heat pump power use up to 50W tapering to 25W then off during these periods of usually 1 cycle/day but three in last 24 hours. Vaillant flow/return temps climb from ~25º to ~50º swiftly and then taper off over hours. I have the heating/cooling and DHW all switched off and my DHW is coming via solar PV charged SunAmp UniQ HW 12+i- VT heat battery. I think the flow/return increasing is coming from a small amount of hot water being pushed out of the SunAmp when the cycling begins. I have various Shelly temp sensors on my SunAmp system which behave exactly as though the heat pump is running a little circulation cycle. I don’t have a DHW cylinder and don’t run legionnaire cycles. I’ve spoken to Vaillant renewables tech support who didn’t really understand my system or issue. Wondering if anyone else has seen this phenomenon or knows what might be happening? Have charts I can share if need be.
20 min would seem long, but for a few seconds each day the circulation pump runs to prevent it getting stuck. 50W sounds like active standby + pump, then 25W is approximately what the heat pump uses when it was recently active. After a few hours.mine drops to 10W in “passive” standby.
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Thx Andre 20 mins was a guess tbh and I just looked closely it’s more like 5-7 mins peaking briefly at 49kW and settling at around 11kW passive. That explains it perfectly and I suppose this becomes unnecessary in winter when it runs daily for longer periods.