Nest and Baxi boiler - I am learning, please help me?

[Kool KG]

Think the override button only switches relay on the 240v side

Thanks Crofton, I am novice, what that means. So if boiler is starting, then why no heating. The purpose of emergency procedure means, when thermostat is not linked, I should be able to operate the heating manually? so what could be solution?

 

[Kool KG]

they can test it from their side , they can look at your install and test it without calling anyone out

Ohhh, they never told me that. 1st job in the morning, I will update you. Thanks for all your help.

 

[Kool KG]

Hi All,

Many thanks for all your support and suggestions. I have sort of fixed the issue and here are the listings of my findings and tips, some of you may find them useful.

1. Even though nothing changed in the house, Nest thermostat lost connection to Heatlink three times this week. Managed to get them connected. Thermostat is in the same room as boiler now, but this is not ideal? I like to move the thermostat back to landing area. What causes the issues with lost connection between Nest thermostat and Nest heatlink?

You may find, Nest thermostat is working fine, but something may trigger the disconnection. In my case faulty Heatling. Another reason I have leaned next door may have moved their internet router, which can cause the new interference without you knowing it. So only way you can fix it by moving the thermostat to different locations until you find the perfect spot without losing the connection to Heatlink.

Are you sure the nest opentherm is not holding boiler off due to inside/outside temps?

over ride function should work regardless of the location of the thermostat, the over ride button is just a switch that tells the boiler to come on for heating, how is the nest powered ? is it a USB cable going into a plug ?

In/out temp will not affect, but I understand Opentherm is not fully functional with every Opentherm boiler systems. Nest will blame the boiler manufacture (in my case Baxi 630 Combi) and boiler manufacture will blame the Nest. By using the Opentherm, energy saving is only 2% extra and you will lose the function of weather compensation and Nest modulating the heating water temperature. However in my case manual over ride will not call for the heating. Hence I have now connected Nest thermostat via wireless to Heatlink and Heatling is connected to boiler as on/off function.

I think you may have a set up issue with the open therm settings, call nest, they can see your settings from their end and can adjust them

they can test it from their side , they can look at your install and test it without calling anyone out

This is not correct, they would not be able to do anything remotely. Therefore I have to arrange Nest Pro to come out to check. Cant fault Nest customer service, quick and prompt, refunded my call out charge too. Now I have installed the replacement Heatlink and connected to boiler as On/Off. To be honest this is NOT ideal for me, I like the idea of Opentherm functionality, but I can't take a chance (ie in an emergency or Nest thermostat lost connection etc) of not having a manual override to start the boiler. So my learning is Opentherm is not a fully tested or functional protocol with every Opentherm devices.

Best wishes

 

[bernardgreen]

Another reason I have leaned next door may have moved their internet router, which can cause the new interference without you knowing it.

Which is yet another example of why it is not a good idea to communicate using Licence Exempt wireless frequencies if that communication has to be reliable at all times.

 

[wrightyintheafternoon]

Just had the same combination installed. Already had Nest but had new Baxi 630 installed. Have had exactly the same symptoms. Boiler would turn on but not fire up and I could not control the hot water temperature.

So the the fix.

Make sure the Nest equipment function is set up correctly. If Nest is set to On/Off you get exactly what’s happening the boiler switches on and off but doesn't call for heat. Set the equipment to Combi-Boiler, make sure to change On/Off to Opentherm, set your boiler water temperature for the heating side and the hot water temperature at the taps and you are good to go.

 

[Kool KG]

Just had the same combination installed. Already had Nest but had new Baxi 630 installed. Have had exactly the same symptoms. Boiler would turn on but not fire up and I could not control the hot water temperature.

So the the fix.

Make sure the Nest equipment function is set up correctly. If Nest is set to On/Off you get exactly what’s happening the boiler switches on and off but doesn't call for heat. Set the equipment to Combi-Boiler, make sure to change On/Off to Opentherm, set your boiler water temperature for the heating side and the hot water temperature at the taps and you are good to go.

Hi,
Thanks for the feedback. That's how I set up for the testing too. But now try to start the manual override function (which is by pressing the Big circle button in the HeatLink), your boiler would not call for the hot water. So when you setup the system as OpenTherm, and Nest unit is off line (which happened few times due to Nest server was off line) then you can't start the boiler for heating!

Please test and give me the feedback, so I can try it again.

Thanks.

 

[wrightyintheafternoon]

OK, I will test by pressing the Heatlink button to see what happens, must admit I hadnt tried that once I had sorted the OpenTherm settings on the Nest thermostat.

 

[ericmark]

I note my Nest says it's hard wired, so I wonder if the 12 volt from heat link to thermostat also sends data? But not lost connection and the boiler is a level below the thermostat so quite a distance.

When I had a problem and turned the supply off it gave this screen

it is clear enough when something has gone wrong.

However what I found was the schedule that needed activating. I set all the times on the PC, but it seems on the thermostat I need to tell it to use the schedule.

When it is running the colour changes like this

with in this case domestic hot water being on, I note you can use different software, not sure which you are using.

where it says Hallway with circle with 20 in it saying you are home, that's the Nest thermostat, on opening you get

however you can also use Nest's own software, it seems only on the phone does it show TRV head and wall thermostat on the PC they are separate.

As to if heating will auto turn down if I am away and wife home I don't know, as yet not got her phone set up. Could that be your problem, is it picking you your phone is away and turning heating down, I do wish it was a little cooler to be frank, shows between 21°C dinning room and 24°C in living room, think an air con would be better today.

 

[wrightyintheafternoon]

I did a quick test over the weekend using the manual button on my Heatlink. Although the Nest Thermostat is all connected and the CH and HW is working as expected. The manual override did not fire the boiler. The fan and pump starts or maybe just the fan but the boiler did not fire. Seems to be a common issue but the wiring is as recommended.