Hot water problem with Nest thermostat

[rscollard]

Hi, 

my hot water is coming on intermittently regardless of nest hot water settings.  I have deleted all hot water timing settings and still my hot water comes on at various times of the day and night. The boiler fires up but the nest thermostat control shows that the hot water is off even though it's heating up.  .  I have had heating engineers out twice and they are baffled.  Is it a problem with the heat link?  Obviously it's getting a voltage intermittently from somewhere.

Thanks all 

[AlexD]

Thanks for reaching out to us here @rscollard . Sorry for the late reply, I would be happy to try and assist you. 

It's possible that this is the Bacteria prevention feature. You can read more about it and how to change the settings here: https://goo.gle/2WTVgRK but in short, it activates the system from time to time to reduce the chance of Legionella bacteria growing in the water. You can turn this feature off, just to test, and see if this changes the behavior of your system. If it does, you can then decide if you want to keep it on or off. 

[Ssb83]

Hi,

Many thanks for the info and link. I did read up on this and that was the exact problem. Since disabling the Bacteria prevention feature, the boiler no longer runs out of schedule. 

If however I left the function on  and the criteria of no hot water being heated for 2 consecutive hours was met, do you know how long it leaves the boiler running on for to heat the water? Assume it's 2 hours?

Also, is there a way on the Nest thermostat / app to see when the hot water has been heating and for how long?

Thanks

[AlexD]

Thanks for letting me know. It is great to hear it is behaving as expected now. Yes, it should stay on for about 2 hours once activated. The hot water is not recorded, like the heating history. Usually most water tanks have a separate thermostat on them, where you set the water temperature. So it can turn off even though the hot water schedule is set to be on. You can only see the set hot water schedule that you set.

[AndaD]

@Ssb83

Hi there again, hopefully the answers my colleague gave you were helpful. Please let me know if you have more questions, I'm happy to assist you.

[george_t]

It's been a while since this thread was last updated so I'll go ahead and lock this thread. If you're still experiencing problems, please feel free to start a new thread and we'll be happy to help.