Better Thermostat constantly adjusts TRV target temperature

[jaynis]

Hi. I experience the situation where Better Thermostat constantly adjusts the target temperature of the managed TRV (Siterwell TS0601 / GS361_Type2), without any changes made by the user (me) and even if it is way below the actual temperature. The following graph illustrates the problem:

The cyan colored line is the actual temperature in my room (measured by an external thermometer), the orange colored line is the target temperature set on the Better Thermostat entity and the purple colored line is the target temperature which Better Thermostat sets on the actual TRV it manages. Most of the time the actual temperature is way higher than the target temperature which means the TRV should idle, however, minor adjustments are applied to it still. I can see that my TRV wakes up every time to process the changes, resulting in a high battery consumption.

I observed the issue gets worse the higher the sampling rate of the external humidity/temperature sensor is, so what I suspect is happening here is that every time the external sensor provides a new value, Better Thermostat recalculates the target temperature (with some error) and sends it to the TRVs.

My question is if this is intended or if it can be considered a bug. If it is intended I would like to know if there is a way how to mitigate this. The behavior I would expect here is the TRV simply doing nothing if the actual temperature is clearly above its target temperature.

[arthurdent2095]

I have a similar issue and I am wondering what to do to reduce the frequency of updates

I am just coming up to speed on the code

[arthurdent2095]

Can you use offset mode on your valves ?

I was only using target temperature mode for debugging and confidence.. and have moved back to offset mode. As expected if you think about it the number of updates per day has now dropped by an order of magnitude.

The max offset on my valves is +/- 2.5 and I know they can easily overhead by 5 degrees so I am seeing where this gets me. I am wondering if I might need an "overflow to using a few degrees of target temperature" feature when the required offset is larger than the max offset but first I need to see how well the temperature is controlled with just this.

Edit: Offset mode really isn't working as well as set temperature mode on sonoff TRVZB devices. I really could do with a hybrid mode which works. The hybrid mode that's recently added its unclear how that works but it doesn't offset the temperature enough from what I can see.

[ishbuggy]

Did you ever figure this out with your sonoff TRVZBs? I am having the same issue with mine, and I cannot find a good configuration where they don't still end up overheating or acting weirdly.

[arthurdent2095]

Yes, offset mode was updated earlier in the year to support */- 7 degrees and since then I have had a stable setup. Something else must have been fixed in the zigbee core because I also have not seen any valve crashes really my network has been very stable. Now its just a case of using it! If a rad is misbehaving it is normally because the underlying mechnical valve needs replacing. I use drayton valves that are 15 gbp from screwfix or toolstation, freeze the tail pipe and swap them quick smart with the radiator sealed the other side. I have one to do at the moment a hammer tap didn’t free it, will do it when I get time, the great thing is the data shows you when a valve is broken!

[Basecatcherz]

I see higher battery drain due to the displays of the TRVs turning on every time Better Thermostat sends an update. And most of the time the update has no effect, as its below room temperatur anyway.

[arthurdent2095]

My batteries are lasting a long long time. Offset mode.

[Basecatcherz]

Oh, completely ignored this section as it only was showing target temperature mode. Sadly mine doesn't seem to support offset mode.