Safety on Hot Water

[Mwpioneer]

Can a hot water cylinder thermostat be connected to a Nest controlled system to ensure that hot water in the tank is not overheated? If so, how?

[CoolingWizard]

First of all, tell us more about your system. What is a hot water cylinder ? What kind of “thermostat” is it currently using?

[DragosC]

Hi there @Mwpioneer. Thanks for reaching out. Could you tell me please what type of heating system do you have? Is it a system boiler with a separate hot water tank and thermostatic hot water control or is it a combi boiler with hot water on demand?

[Mwpioneer]

Replying to both "Cooling Wizard" and DragosC

I have just had a replacement boiler fitted and the engineer fitted a Nest Learning thermostat. It was a more efficient replacement for a boiler with a separate hot water tank (often called cylinders in the UK, from the normal shape) which had a simple on-off thermostat in it, together with a simple timing control to control heating of hot water. The cylinder/tank is retained but he does not seem to have connected the thermostat. We also have solar water heating which feeds into the cylinder/tank but this does not interact with the Nest thermostat system at all. When the Nest is set to boost or on for hot water, it heats to the temperature of the water leaving the boiler. So I have had to reduce this somewhat to be what I consider a safe temperature. Reconnection of the thermostat would seem a simple answer ,but presumably the thermostat would continue to call the boiler to provide hot water and open the relevant valve, so would not be advisable ?

I would be grateful for any advice.

Mike

[AlexD]

Thank you for the information. The thermostat, with the Heat Link, acts like an on/off switch basically. When you request hot water it will move the internal relay to the on position and activate the system and when turning it off, it would switch the relay to the off position deactivating it.

There is temperature control for the water but this is only available for combi boilers with OpenTherm compatibility.

Usually the temperature of the hot water in the tank should be controlled by a separate thermostat on the water tank. So the thermostat on it would stop the hot water supply to the tank once the water in it has reached the set temperature on it even if the Google Nest thermostat is still scheduled or set to boost.

[george_t]

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

[AndaD]

@Mwpioneer

As this thread wasn't updated in a while, I'll have to go ahead and lock it. You can always reach back and start a new one if needed. Thanks for understanding, stay safe and take care!