I've recently bought 4 Nest thermostats for my home:
1x Nest 3rd generation learning thermostat
3x Nest E Thermostats
I'm running a heat only system (radiant floor heating) with two wires R and W, with a Viessmann Combi boiler.
I've noticed some issues regarding after my installation, most likely due to the lack of a C wire and the power stealing pulses to my boiler.
Although I've set the temperature to be very low (around 15 to 17 degrees Celsius) always, the temperature in the room when I woke up was 22.5, much higher than I expected. Upon checking the nest app, it said that it had done no heating whatsoever but I noticed that my floors were quite hot where the nest thermostats were installed and my boiler application had indicated a significant use of gas due to heating throughout the night. This has been happening ever since I installed the nest thermostats replacing my old simple honeywell ones. Even when the temperature is set to very low, or the room is already higher than the set temperature, the nest thermostat still seems to heat the room.
I did some research and found out that the nest thermostats power steal and I believe that the small pulses of power that the thermostats steal is causing my system to continuously turn on and off which leads to the undesired heating.
I do not want to damage my system and have any unnecessary heating so I wanted to create a post on the community to see if I can come to a good solution.
I did some research and found a couple plausible solutions that I wanted to get some feedback on.
1. Add the nest power connector.
I saw that the nest power connector is able to add additional power the the R and W wires? I'm most likely wrong on how it actually works, however I wanted to know that if I were to install the power connector, would this completely prevent the power stealing/pulse like behavior to my boiler and/or fix my problem with the undesired heating?
Regarding the power connector as well, I've read that its possible to receive a nest power connector if you're having power issues. Would my current situation be eligible, or is that program still available?
2. Add a 24V 500ma transformer.
E.g. Plug into the wall, and the other end to the Rh and C terminals on the thermostat backplate. I saw this solution online somewhere and it seems to be the easiest although i'm worried about compatibility.
3. Sell my Nest Thermostats for a loss and reinstall the Honeywell.
This is just what I've found online, it seems like there are many others with similar issues. If there's a better solution please let me know, I would not like to cause any damage to my boiler.
Thanks!
