Heating pump running when boiler off

[Nick1865]

We are finding that the pump starts running at random times of the day and night when the boiler isn't running. We can't stop it except by switching off the power supply to the pump.

[AlistairL]

Hi Nick1865, Are you seeing a ‘curious’ icon on your thermostat? I have the same behaviour when the heating and water are off but the thermostat shows a yellow circle with a black teardrop on the screen. I mostly notice it during the night when all else is quiet.

I posted a query about this a couple of weeks ago, someone called Jake responded but I’m sad to say I didn’t follow up on it (sorry Jake). Maybe Jake could reopen my query and ponder them both?

[Markjosephp]

Hello folks,

I’m sorry to hear you’re having trouble with this. I'd love to know more about this.

@Nick1865, what type of Nest Thermostat do you have? Did you enable the heat pump settings? Also, does it occur on a specific time?

@AlistairL, I was able to review your previous thread and saw a picture of the icon you're seeing on your thermostat screen, which appears to be a humidity icon. You might have enabled its schedule and adjusted the level, which you can find in your actual thermostat's "Equipment" settings.

Let us know how it goes.

Thanks,

Mark

[AlistairL]

Hi Mark, thanks for getting back to me. I’m not aware of having enabled any humidifier settings and can’t find any schedule for it in the Equipment settings. However, a trawl of the internet turned up that it might be Bacteria Prevention, which is On.

My main issue is that the pump is running (and ‘wasting’ electricity) for several hours in the middle of the night. I think I might disable it and see what happens. Hope we don’t catch Legionaires.

Any thoughts?

[AlexD]

Hi there @AlistairL . You are correct, the icon you saw there is for the Bacteria prevention feature. 

This is something that is present on EU thermostats and not on US ones.

You can read more about bacteria prevention here but in short, this feature activates the hot water heating if the hot water schedule did not have an active period across two days of at least 2 consecutive hours. If the feature is enabled and the hot water is not on for at least 2 consecutive hours across the last 48 hours, it will activate, keeping the system on for some time, to reduce the risk of Legionella bacteria developing in the system.

See how the system behaves once it is disabled but I would recommend you either enable it or set up a schedule so that every 2 days the hot water schedule is on for 2 hours during the day when it does not disturb anyone. 

[AlistairL]

Hi AlexD, thank you for your feedback on this. We usually run our hot water for 1 hour each end of the day, which provides sufficient. Prior to getting our Nest thermostat we used the same hot water schedule, so I think I will leave it off for a while. We managed to dodge Legionella in the 15 years before Nest so will take the gamble.

Nevertheless, glad I understand this better and thank you for your help.

AlistairL

[UanaC]

Hey @AlistairL, I am so glad that this helped. @Nick1865 are you still facing the same issue?

[OannaCG]

Hi there! Just wanted to check if there's anything else I can assist you with. 

[AlistairL]

Hi OannaCG, thanks for getting in touch. I think I am all sorted. I’ve not re-enabled the Bacteria prevention option on my Nest. I’m going to wing it, nothing untoward has happened for the past 15 years so hoping it will stay this way.

best regards

AlistairL

[OannaCG]

Great! Should anything else come up, we're just a message away. Have a great day ahead and stay safe!