Can 3rd gen Nest thermostat take input from cylinder stat?

[fletch555]

I have a 3rd gen Nest Thermostat set up to heat my radiators and hot water.  I want to add a hot water cylinder stat to avoid the Nest continuing to fire when the tank is up to temperature.  Can the Nest accept input from a cylinder stat (like this for example https://www.screwfix.ie/p/honeywell-home-l641a-cylinder-stat/40051#product_additional_details_contai...)?

[DragosC]

Hi there @fletch555,

Thanks for reaching out. The Nest Heat Link can control the hot water tank with a programmer as well, as long as the programmer is kept on "Always on" mode. 

[fletch555]

Hi @DragosC 

Thanks for responding but I'm not sure I follow your suggestion and how it would help my use case.  I already have the Nest controlling the hot water as per a schedule.  My issue is that I want to stop the boiler firing once the water reaches the desired temperature.  Is this possible without an OpenTherm boiler?

[DragosC]

No worries. Let me explain.  Usually the way you were explaining works, but we cannot guarantee that it will be 100% compatible, depending on the product. In this case, we recommend you contact a certified heating engineer to check on that. 

[fletch555]

@DragosC 

Sorry to be pedantic but do you know if the heatlink can accept a signal from a cylinder thermostat to tell the boiler to stop firing? 

[DragosC]

No worries. The Heat Link is not an input device, it is an output device, and the signal comes from the Heat Link, goes to the cylinder stat, and the cylinder stat decides if the temperature is enough and stops the cylinder or if it needs to be increased. The Heat Link signals the cylinder based on time, not on temperature. 

[george_t]

Hi @fletch555. Just checking in, is there anything else we can assist you with at the moment?

[CristianC]

Hey there. I haven't seen any updates in a while so I'm going to lock this thread. If you're still experiencing issues, feel free to open a new one.