vaillant v34 - AO Extension

[Nick Barton-Wells]

Hi all,

Has anyone had much success using the Vaillant VR34 0–10V module with the Loxone AO Extension?

At the moment, I'm just using basic on/off control for my Vaillant boiler, but I'd like to improve how it runs by adding the VR34 module and using 0–10V modulation.

Thanks!

[Bartel Eerdekens]

Using the VR 34 here since quite a long time, not with an AO, but just an analog output of my Miniserver (V1).

But many people are doing it this way.

See this (Dutch) Facebook group for more info: https://www.facebook.com/groups/126010224686679/search/?q=VR34
Either a search on this group also gives some results.

Setup: Connect 2 wires (GND + 0-10V) from analog to VR 34.

Config in Loxone, keep in mind to re-configure min/max values: 1V is actually the minimum temperature, 10V is your maximum.

Quite easy to do and works very stable here!

[SteveJ]

Hi Nick

I’m using the VR34 to control my boiler from Loxone  albeit  via a Modbus 0-10v unit rather than a loxone AO as the AO seemed too expensive to justify for this single use.

I’d say overall using this to be an improvement over not using it and driving the builder solely via an on/off relay, but like a lot of things in my system, I don’t feel I ever really found time to finish experimenting so Its likely I’m not seeing the whole picture (yet…)

My system is currently still generating an on-off for the mains input of the bolier as well (mainly because I’ve not got around to testing without it) but I understand from other contributors to the forum that this on/off is not needed once the VR34 is hooked up as 0v effectively means off.

My 0-10v output is connected to the output of a Flow Temperature Calculator (which is in turn connected to all my IRCs).   This seems to give a temperature compensated output to the boiler which varies by demand and outside temperature.  I’ve yet to look at tuning the output in any detail, but at a high level I can tell by reading the boiler telemetry via ebusd that it is varying the boiler’s flow temp and keeping the boiler within the limits for condensing operation more of the time.  I also have a bit of logic to override the output of the FlowTempCalc when there is demand to heat the hot water tank - this sets the boiler flow temp to 65 to ensure I can get the water in the tank above the legionella temp of 60.

My VR34 has two modes - output set and flowtemp set, my experiments seem to show that using flowtemp set mode is more effective.  For my 30KW boiler I also changed the part-load setting in D.000 from auto to 20KW (based on some commentary in a previous thread in this forum) - this seems to stop the boiler taking ages to get unto the desired FlowTemp.

Not strictly Loxone related, but If you are not already using it then I can recommend ebusd and HomeAssistamt to read the boiler’s telemetry and settings - takes a bit of configuring and there are still a few holes in what it can do, but on the whole this provides me a really good view of what the boiler is doing - and helps enormously when fiddling with things like the VR34.

Hope that helps

Steve

[Nick Barton-Wells]

Thanks both, that's really helpful.

@Bartel – thanks for confirming the setup. It sounds much simpler than I was expecting, and it's good to know it's been stable for you over a long period. I'll make sure I configure the AO scaling correctly so that 1–10 V maps to the boiler's minimum and maximum flow temperatures.

@SteveJ – thanks for taking the time to explain your setup. That's exactly the sort of information I was hoping for. Using the Flow Temperature Calculator with an override for DHW makes a lot of sense, and I hadn't considered using eBUS to monitor what the boiler is actually doing.

Out of interest, which eBUS adapter are you using? There seem to be quite a few available, so I'd be interested to know which one you've had good results with, and whether you're connecting it to Home Assistant via USB or over the network.

Thanks again to both of you!

[Steve Joyner]

Hi Nick,

I connect to my bus adapter via ethernet.  ebusd is running on my linux server and pushing data out to HomeAssistant over MQTT (it also plays nicely with HomeAssistant's auto discovery over MQTT ).  I think it’s possible to run ebusd as a HomeAssistant add-on which would remove the need for a separate server.  I think there are also some adapters around now that allow a version of ebusd to be run directly on the adapter - although I seem to remember there is a subscription required to unlock this functionality.

I can’t be much help with bus adpater choice s mine is so old its long been discontinued. - I use an old model of an esera  eBus adapter that is no longer available mine is a previous version of this: https://esera.de/en/Produkte/12002/EBC-200-eBus-Coupler-Ethernet (which also looks like it might be EOL now).  Mine is 10 years old an still working fine - its on the end of a long cat5 cable connected to the bus at the boiler.  I don’t currently have any Vaillant controls so its just the adapter and the boiler on the ebus, 

The one thing that annoys me about the adapter is its form factor (same as the one in the link) because its a standard module depth, but with the ethernet port on the front, the ethernet cable sticks out to far to allow it to fit in my FutureAutomation cabinet  with the cover plate and door on, so its has to float in the bottom of the cabinet with the ethernet port facing upwards.

Steve.

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