TRV demand doesn't trigger boiler to switch on

[shaftspanner]

First of all, many thanks for all the hard work that's gone into Versatile Thermostat, and for the support that I've already received while I've tried to setup my heating.

My setup consists of

• 3 Sonoff TRVs configured as over-climate VTherms. Each uses the relevant Sonoff TRV as the underlying entity
• 1 over-switch VTherm. This uses the central boiler switch as the underlying entity as there is no separate switch for this radiator
• 4 VTherms are configured to be used by the central boiler so if I understand the documentation, demand from any of these VTherms should trigger the central boiler to fire
• I have a central boiler configuration. This uses a Sonoff ZBMiniL2 relay to demand heat from the boiler

I have found that:

• Changes made in Versatile Thermostat are reflected in the TRVs i.e. the TRV valves will open and close as expected if I change the required temperature and if there is heat present, the radiators will get hot when expected
• Changes made to the over-switch VTherm result in direct control of the boiler - if I turn up the over-switch VTherm temperature, heat is demanded by the central boiler and the radiator gets hot

but:

• Demands for heat from the over-climate VTherms don't trigger the central boiler to fire.

I've tried to illustrate my current setup below

1. This is the Sonoff ZBMini that actually triggers heat from the boiler. It is also switched directly from the Hall VTherm as this radiator isn't fitted with a TRV and is always open so the boiler can't fire without having somewhere to send the hot water. I need to maintain independent switching for this radiator as it heats a large hallway, stairwell and upper floor landing, so I don't want to rely on it only heating because one of the other rooms needs heat.

I've been monitoring the central configuration entities/attributes, so I can see the quantity of VTherms demanding heat, and which specific VTherms are demanding heat, but unless the Hall VTherm (VTherm over switch) is demanding heat, the boiler won't actually fire

If there's more information I should provide to help with this question, please let me know

Edit: I realise the blue "water pipes" from the boiler to each radiator don't actually flow like this and it's actually a loop - this is just for illustrative purposes!

[shaftspanner]

I've updated the diagram as I realised I hadn't shown the relationship between VTherms and the Central Configuration:

[jmcollin78]

Hello,

Before answering totally and fully read all your post, I don't understand the need of the over_switch. If it is only to control the central boiler, there is no need of a VTherm for that. A central configuration is enough.

Second, with Sonoff TRVZB, you should not configure the "closing degree" as explain here: https://github.com/jmcollin78/versatile_thermostat/blob/main/documentation/en/self-regulation.md#self-regulation-by-direct-valve-control

If "closing degree" is configured, the hvac_action of the Sonoff TRV don't work and then VTherm can't know that the VTherm need for heat and don't activate the central boiler.

You should first those 2 tips before going on further.

[shaftspanner]

Hi @jmcollin78 thanks for your response.

I don't understand the need of the over_switch. If it is only to control the central boiler, there is no need of a VTherm for that. A central configuration is enough.

The over_switch is included so that I can trigger heat to the hall radiator without also heating the other rooms. The hall radiator doesn't have a TRV so is always heated if any of the TRVs are active, but I want to be able to heat that area on it's own as well.

Second, with Sonoff TRVZB, you should not configure the "closing degree"

I'm haven't. in the underlyings section for each TRV, I've selected "no auto-regulation", so I don't think "closing degree" is applicable.

However, I think I found a solution to my issue:

When I was drawing the diagram above, I realised things didn't look quite right connecting the hall over_switch VTherm to the same phyical relay as the central configuration, but the over_switch VTherm obviously requires a switch entity to do it's thing - so I created a toggle helper to fulful this role. The toggle helper doesn't actually drive anything, but it allows the hall over_switch VTherm to be configured and allows the central configuration to be the sole driver of the ZBMini relay that actually triggers the boiler.

I'm not sure if this is the way you intended it to work, but it appears to solve my problem. The hall over-switch VTherm can now trigger the boiler to deliver heat, but each of the over-climate VTherms in the other rooms can now also, independently trigger heat from the boiler.

I've updated my diagram to show the new configuration. Grateful for any feedback on this.

[jmcollin78]

When I was drawing the diagram above, I realised things didn't look quite right connecting the hall over_switch VTherm to the same phyical relay as the central configuration, but the over_switch VTherm obviously requires a switch entity to do it's thing - so I created a toggle helper to fulful this role. The toggle helper doesn't actually drive anything, but it allows the hall over_switch VTherm to be configured and allows the central configuration to be the sole driver of the ZBMini relay that actually triggers the boiler.

Yes it is better like this. Controling your central boiler with an over_switch is really not a good idea because start and stop are constant.

in the underlyings section for each TRV, I've selected "no auto-regulation"

You should try the self-regulation with direct control of the valve of the Sonoff TRV. It gives great result. This is certainly the best way to regulate a TRV with an external temperature sensor.

You have a great installation. Don't you have no more issue with the boiler starts ? To works fine, this feature need to have a working hvac_action on each TRV climate. This attribute tells if the TRV is claiming for heat.

You have also a way to see which TRV a claiming for heating. In the sensor called sensor.nb_device_active_for_boiler you have an attribute named active_device_ids which lists the active underlying devices.

Example:

The heater named 'switch.radiateur_mezzanine' is currently claiming for heat.

[shaftspanner]

Thanks for your help with this. I've been monitoring for a few days and I'm now comfortable that it's doing what I expect - I've also implemented the direct-control-of-valve regulation and I'm tracking how well that performs.

Now onto refining the system!

[jmcollin78]

You have a french (but should be easyly translatable) post that explains how to tune your VTherm: https://www.hacf.fr/optimisation-versatile-thermostat/