Google Nest Heat-Link: Works manually, but not via app

[P12af]

Hello,

I have the Nest Heat-link 3rd Gen installed and I have the app downloaded on my iphone.  When i click on the 'Boost' function within my app, it turns orange and displays on.  The spring in my HW zone valve also clicks but the boiler does not fire up.  However, if I manually turn on the heatlink by pressing the large white button, the HW zone valve clicks and the boiler fires up.  All my heating controls work, so this issue is related to HW only (incidentally, I have Hot Water set to "On" within the App settings). 

What could be the reason for this?

Thank you for your help on this matter

[AlexD]

Thanks for reaching out @P12af . I would be happy to try and assist. 

First, just to check, is this a new installation on a system boiler with a separate hot water tank? Was it installed by a Nest Pro installer or by a professional installer/engineer?  

[P12af]

Hello AlexD,

New installation, about 3 months ago.  Worked relatively fine for 2 months and been having problems over last 3 weeks.  installed by a professional plumber / electrician who has installed Google Heat-link and Nest before, but not a 'Nest Pro' Installer.  I have the Vailant ecotec Plus system boiler.

Look forward to hearing from you

Praf

[AlexD]

Thanks for clarifying. When using the button on the Heat Link, the manual mode, this engages both the heating and the hot water, so if you left it running for some time you would notice your radiators getting hot and that there is hot water in the tank. So the fact that you hear the boiler and the water tank works when using the manual mode is certainly expected.

Of course when boosting the hot water, the water heating should also activate. The only reason why it might not activate is if the hot water tank is already filled with hot water and the thermostat on it will not allow it to turn on. Most water tanks have a separate thermostat on them where you set the max temperature of the hot water inside. So if the water level is full and the set temperature is achieved having the hot water scheduled to be on or boosting it would not activate it. 

Since you hear the valve engage when boosting the hot water that would indicate that the thermostat is sending the signal to the Heat Link and the Heat Link is activating the internal relay, actuating the valve for the hot water. We can do a quick click test on the Heat Link just to double check. 

1. Go to the Nest app and select the hot water control.
2. Tap on the cogwheel in the upper right corner to go into he hot water settings and toggle the first option there off. This will turn off the hot water schedule, you can enable it back after the test.
3. Boost the hot water for any amount of time and listen for a clicking noise.
4. Turn the boost off and listen for a clicking noise again.

Let me know if you hear the clicking noises from the Heat Link. 

[P12af]

Hi AlexD,

Thanks for your reply.  By pressing the manual button, you are right that it triggers the heat and HW, however my thermostats are set at 18c and the temp in the house over the last 4 days has been 22c+, so only the HW should trigger, not the heaters.

To your second point, the water in the tank has been too cold to shower, despite the HW schedule on my app requesting it goes on for 3 hours in the morning and 2 hours in the evening. It just does not heat up at all. 

I followed your programme and the clicks occured, even with the toggle switched to off

[AlexD]

The manual mode overrides any command from the thermostat display. So even if the heat is set to be off on the display, it will turn on the heating and hot water. Manual mode is designed for troubleshooting and to be used in an emergency, like if the display is no longer operational and you need to activate the heating/hot water. 

The toggle for on/off is only for the hot water schedule. It is best to have it off just to make sure the schedule does not influence the test.

If the Heat Link clicks as expected, and you mentioned the valve is activating, that would indicate that the thermostat is working as expected. It is most likely something else in the system that is causing this behavior. 

I would recommend in this case for a Nest Pro or a professional installer to check over the whole system. They can even contact us over our live phone or chat line when they are there and we can walk them through any troubleshooting and tests on the Heat Link. We can perform a continuity test with them using a multimeter, but since the Heat Link clicks as expected it most likely would indicate the same. If you have a multimeter and are comfortable in performing some tests on the Heat Link I can send you the test steps over email.

Now if they do locate something going on with the Heat Link, although based on everything so far it seems unlikely, if you are in a supported region and the unit is in warranty with a diagnostic report from the installer we should be able to replace it. A diagnostic report is a document that contains all the installers details as well as yours together with all the tests they have done and what they found is causing the behavior. I can send an email with a template for it should you wish to the email associated with your account here. 

[P12af]

Thanks.  For the time being, I'll call my plumber to have another look at the system as the installation is still under warranty (I hope!), but otherwise, I'll locate a Nest Pro installer.  I'll revert with the findings if related to faulty Heat-link unit. 

Thanks

Praf

[AlexD]

Make sure to keep us posted here on how things go and if you need further assistance. Have a great day ahead and stay safe!

[OannaCG]

Hi! Just checking in, is there anything else I can assist you with?

[UanaC]

Hey there, I haven't heard from you in a while so I'll be locking this thread. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community. Thanks, Oana.