Boiler turning on when Nest says heating & water heater OFF!

TVR450

I woke up last night at 2am to find the boiler on, I checked my Nest thermostat and it was showing heating off but it had a yellow symbol displayed. I checked it out this morning and it turns out there is a new feature to heat your hot water to kill Bactria, even if hot water is not scheduled.

To adjust this setting, go to your Nest thermostat and press it in, turn the ring until you see EQUIPMENT press it in and then pres in again on CONTINUE. Next select BACTERIA PROTECTION - here you can disable or enable this feature.

MoneySaver1974

Hi, adding to this post as we got a nest gen 3 for xmas 2019. All working well - installed myself (thanks YouTube) but yesterday I noticed that the boiler was firing when no heating or water should have been on. Very disconcerting I must say, we have an normal oil boiler Y Plan and a 3 way control valve. I noticed a yellow droplet icon on the stat, and this is the legionaries setting - even though we have the water set to an hour in the morning and an hour in the evening.

Bit worried that nest sent out engineers to people before checking this simple software setting. Does make you wonder about so called professional service.

Hope this helps people like it did me. I like the nest system in general though.

siany42

Hi, can you tell me if you resolved this issue as we are having the same problem! Thanks 

ImranQ

siany42 said:

Hi, can you tell me if you resolved this issue as we are having the same problem! Thanks 

Hi - Yes we finally resolved the issue. Yours could be a different issue but I will briefly describe our problem...
It turned out that the the electro-mechanical switch that turned on the hot water in the heating system had died and was kept coming on randomly. To replace the switch the whole system has to be drained but funnily enough, it was only the electrical part of the switch that died, saving us a huge expense. Once the electrical part was replaced (there are two parts to it and the electrical part can be replaced without draining the system) everything worked normally.
A few months later the heating switch (there are two in the system - one for the hot water and one for the heating) also went and had to be similarly replaced!
Good luck - Imran

JQ2

Hi - for those of you still having this issue - I found this and it seems to have worked. 

Lacala_3

Turn OFF the "bacteria" setting in Equipment option.

FreeBear

Necro posting on a thread that was started way back in 2018, and resurrected a couple of times with the same "advice" from one post wonders....