Sonoff TRVZB with thermostat_over_valve

[johnbur1]

I notice that the latest Sonoff firmware (1.1.5) and the latest zigbee2mqtt exposes 'Valve opening degree
Valve open position (percentage) control'
'If the opening degree is set to 100%, the valve is fully open when it is opened. If the opening degree is set to 0%, the valve is fully closed when it is opened, and the default value is 100%'
Does this mean that I should be able to use thermostat_over_valve instead of thermostat_over_climate with this TRV now?
Anyone tried it?

[jmcollin78]

Hello @johnbur1 ,

Yes ! And controling directy the valve is far away the best solution. You will not depend on a regulation algorithm elsewhere.

I suggest to switch to 'over valve' VTherm. Do to that you have to recreate it (you cannot change the type once created).

Thank you for the information, it could be an interesting information for those who want to buy some compatible TRV.

[tbrasser]

I think we don't have actual valve control here. It's just 2 settings to set the percentage in fully open and fully closed positions. (And by default open position is 100% open, and closed position is 100% closed (= 0% open).

(I have 2 of these with firmware 1.1.5 on latest z2m edge)

[johnbur1]

Shame, I was hoping that someone much more clever than me would be able to make this work :-(

[tbrasser]

Maybe if you set one the inverse of the other you force it in that position? (open=75, closed=25, valve forced at 75%?)

[johnbur1]

It works! The 'Valve opening degree' is not enabled by default in HA, but once enabled, you can adjust the valve open % manually and the valve responds immediately.
VT 'over valve' also controls this perfectly.
We do seem to have actual valve control after all!

[jmcollin78]

This is really a great news. I will add that in the README.

[johnbur1]

Update - all working perfectly - have re-done all my trvs.
Even easier than I said - the 'number.trv_name_valve_opening_degree' entity is already enabled in HA, it wasn't on the first one I tested, and you don't need anything in configuration.yaml after all. I factory reset my test one and all ok straight away.

Only thing to remember is to set the internal TRV setpoint to 35deg so it does not ever close the valve itself!

[johnbur1]

@jmcollin78 Loving thermostat over valve with the Sonoffs - many thanks.
One question I have, I am noticing that at low opening % in VT, the danfoss valves I use really don't let any water through, so I am finding that if using central control, the boiler can be triggered with no water flow. Is there any setting I can use that can specify a minimum %age before the boiler fires?
If not, is this something you could consider?

[jmcollin78]

Hello @johnbur1, There is a threshold that starts the boiler only if more than x VTherm are active.
Do you think you can use this threshold to avoid starting the boiler ?

On the other hand, you can define your own min and max for all VTherm. Maybe those threshold will do what you want.
The behavior is the following:

1. VTherm calculate an open percent,
2. if open_percent < min, then set it to min,
3. if open_percent > max, the set it to max.

That is not exactly what you want but there is a chance that it does the trick. Try to put the min let's say to 5% and tell me if it does what you want.