Hot water not always following schedule

[BeccaC]

We’ve found recently our hot water isn’t always following the nest schedule. It seems to be completely random that some mornings or evenings it doesn’t switch on. 
Has anyone else experienced this or does anyone know why it wouldn’t just heat at the same times every day? 

[AxelD]

Hi BeccaC,

Thanks for posting in the community! Sorry to hear that your Nest Thermostat isn't following your Hot Water Schedule. No worries, help is here! I'd like to ask you some questions to gather more information about this:

1. What type of thermostat do you have?
2. Do you have a system or a combi boiler? Is the control On/Off or Opentherm?
3. What's the status of the Heat Link's LED light
4. Have you checked this article about Domestic hot water control? It contains some troubleshooting steps. 
5. Is there a pattern to the hot water activating? Is it happening every day, or at the same time each day? 

Keep me posted.

Regards,

Axel.