Room temp 23, thermostat 16

[wilcoxc]

As the title say, the thermostat is set to 16 degrees Celsius.

Last night I spent the night in the living room with our new puppy and the radiator was blasting out heat. It got to 23 degrees Celsius.

What’s going wrong. This is costing me an absolute fortune!

[fortean]

Is your nest in the same room where the radiator blasted out heat?

[wilcoxc]

Yes it is

[fortean]

And is that a small or big room? Is your Nest in OpenTherm mode or On/Off mode?

Without more data / information nobody can do anything with your question, I'm afraid..

[wilcoxc]

It’s a relatively small room.

It’s in on/off mode with a schedule 18 degrees during the day and 16 at night.

[fortean]

On your heater, have you set the flow temperature of the water? If your heater has, say, a flow temperature of 75/80 degrees (Celsius), and you only have on/off switching, it may well happen that the radiators will radiate (ahem) too much heat. The Nest will probably eventually learn to cope with that, but it may take some time.

[AlexD]

Thanks for reaching out to us here @wilcoxc . I would be happy to try and assist. 

Thank you for all the shared information and assistance @fortean, even in French! Awesome job. 

For starters, how long has the thermostat been installed and working as expected before you first noticed this behaviour?

Is the display orange, heating on or black., heating off, when you notice this behaviour? 

[wilcoxc]

Hi @AlexD,

Thanks for replying. We have had it installed for over 1 year.

We don't think that it has ever worked properly as we had issues last year which we attempted to resolve by setting up schedules etc... but nothing seemed to work. This year however, the cost of gas is considerable and we need to try and rectify this situation.

I have turned eco mode off and I have turned of home assist to reduce the number of variables that could be causing an issue.

The heating display is orange and will state that the room temperature is 23 degrees but that it is set to 18. 

It seems that it is not communicating properly with the boiler and the boiler continues to fire, despite the nest being set to a lower temperature than the room temp.

[AlexD]

Thank you for the information. Please go to the Nest app and take a screenshot of the schedule and share it with me here. This way we can all have a better idea of what the expected behaviour would be. 

Just to confirm, the big number in the centre of the display was 18 and the small number off to the side was 23 with an orange display? If you do happen to see that occurring again make sure to grab a picture of that as well. 

[wilcoxc]

Here are the screenshots that you requested: https://imgur.com/a/9COpA7e

The radiators are on and still pumping out heat despite it being set to 18 and the room temp currently at 21.

[AlexD]

Thanks. Based on what I see in the screenshot, the heating should be off, the page is white. When the heating is on, based on the thermostat settings, the page would have an orange hue. 

Let us do a test on the Heat Link using the Nest app. Go next to the Heat Link:

1. Open up the Nest app and make sure the heating is still set to be off.]

2. Turn up the temperature until the heating should be on, page goes orange, and listen for a clicking noise from the Heat Link.

3. Turn the temperature down again so the background on the page goes white again and listen for a clicking noise again. 

Let me know if you hear a click in each of these cases. This way we can have a quick look to see how the relay in the Heat Link is behaving. 

[Vladut]

Hi there, just checking in with you. Did you manage to check the last message?

[Paul_R]

Hi there @wilcoxc! Since you didn't manage to respond to the last two messages sent by my colleagues, I'll need to close this thread. If anything else comes up, feel free to reach out!

[Wycem]

Bonjour, 

J'ai exactement le même problème chez moi. Température réglée à 19 et il fait 24 chez moi. La chaudière tourne et chauffe sans arrêt. 

Installation : chaudière à gaz avec radiateur. Marché/arrêt. Heat link en contact sec. 

Il me semble que le thermostat n'envoie pas le message d'arrêt correctement pour arrêter la chaudière. 

J'ai fais des tests en mettant le thermostat en mode éteint et ça ne donne pas de résultat. 

Redémarrage en mode usine. Le problème persiste. 

[fortean]

L'affichage indique-t-il que le chauffage est allumé - est-il donc orange ? S'il est noir et que votre radiateur fonctionne toujours, vous avez probablement fait une erreur de câblage.

[Wycem]

Après vérification, l'affichage est bien noir alors que le chauffage est en marche. Ce qui laisse entendre qu'il y a une problème de câblage d'après votre réponse. J'ai vérifié le cablage, il est bon. (notice Nest respecté) 

À ce jour, le problème n'est pas résolu. J'ai déconnecté la Nest et gère ma chaudière sans. 

[fortean]

La connexion marche/arrêt peut être établie de 2 manières : toujours allumée ou toujours éteinte. Si vous connectez les câbles de manière incorrecte, le système ne fonctionnera pas correctement. Il y a un mode "toujours allumé" et un mode "toujours éteint", vérifiez si tout s'est bien passé.

[Wycem]

Salut, merci pour ce retour. J'ai connecté 2 fils en 2 et 3 (contact sec) comme c'est précisé dans la notice d'installation. Il y a pas de couleur à respecter. Je peux faire une photo si vous voulez ?  

[Wycem]

Ci-joint une photo de la connexion heat link 

[fortean]

Le câblage semble OK. Si vous débranchez le thermostat et appuyez sur le gros bouton du heatlink, le chauffage s'allume-t-il ?

[Wycem]

Oui le chauffage s'allume. Mon problème est que le chauffage se déclenche même quand la température est au dessus de la température demandé. Et dans ce, il marche en continu. 

[fortean]

Mais bien sûr pas si vous débranchez le thermostat, n'est-ce pas ? Il peut également s'agir d'un court-circuit dans le câblage.

[fortean]

Setting a lower flow temperature may result in your heater having to be 'on' more, but as it consumes less energy, all in all you will probably still save energy.

[fortean]

All in all: if you only recently installed your Nest, it is still learning about your setup. It will detect that the temperature has risen too high and will adjust the duration of the "On" period (an probably the start of the "On" periods too).  It has no other ways to control the temperature, it can only set your heater on or off. It will eventually "learn" that your room gets hot quite quickly, and adjust the periods accordingly.

You may also set the flow temperature on your heater to e.g. 60 degrees C and see what happens. The Nest will probably be a bit confused as suddenly your profile changed, but will assumedly adopt quickly.

(All this of course assuming that your Nest also shows that your room is 23 degrees, eliminating that it simply has a defect or hangs in a cold spot etc. - if it has a defect, you should get a new one from Google / your vendor, guarantee).