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Thread: Vaillant boiler monitoring - anyone doing it?

  1. #1
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    Default Vaillant boiler monitoring - anyone doing it?

    Having just spent an hour rewiring my S plan+ system so that the Evohome + OT bridge had almost complete control of it, I started thinking of my next project.

    Today I put the Evohome into Away mode and for the longest time the OT bridge gave the boiler a target temperature of 10C, which means OFF. However suddenly for no reason it put the target temperature up to 33C, but because the flow temperature was already 41C in the boiler, the boiler didn't fire up.

    My current setup is
    1. Boiler is now completely controlled via the OT bridge -> VR33 -> Vaillant boiler. I can see varying target flow temperatures being set. And the OT bridge is firing up the boiler too after all the wiring modifications I had to make inside the boiler PCB (i.e. jumper between 3-4, jumper between 7-8)
    2. Heating pump is controlled by the boiler and now I've rewired my system, so that the CH motorised valve opens whenever the pump is running. So effectively I don't have a CH valve any more.
    3. All the radiators besides two towel rails have the radiator controls on them.
    4. I do have the HW kit as well with a HW valve.
    5. One CH zone is UFH with a T87RF sensor and a BDR91 set up as a Zone Valve operating the UFH pump and it's own zone valve.

    I now want to see what the boiler is actually up to. My boiler is up in the loft so visually monitoring it proves difficult. In fact the entire set-up is so silent, I've had to repurpose the old wired room stat to come on when the pump was running, so I knew the heating system was on - doing something!

    Is there anyone who is successfully monitoring a Vaillant boiler? I have quickly built a read only eBus interface. I want to be able to monitor the flow, return, target flow temperatures and flame status. I know I can monitor flow and return via external sensors but would like the boiler's own view.

  2. #2
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    Anyone? I used some software called ebus connector and now using something called ebusd. Can see lots of messages but neither software is able to read anything yet.

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    Several days later and pouring over logs of Hex messages, I am finally at a position where I've got the 4 basic data points that I was looking to measure from my Vaillant boiler i.e. Flow Temperature, Return Temperature, Target Flow Temperature (as set by Opentherm) and Flame Status. Goodness me it was tough going. But without the ebusd software I wouldn't have even started.

    Although I've only actually ever seen a few Target Flow Temperature (as set by Opentherm) on the actual boiler, over a period of a day I saw that the OT bridge used an entire range of temperatures.
    10C, 35C, 40C, 42C, 50C, 55C, 57C, 58C, 59C, 60C, 61C, 62C, 63C, 64C, 65C, 67C, 68C, 69C, 70C, 71C, 72C, 73C, 74C, 75C, 76C, 77C, 79C, 80C, 90C

    10C normally means that everything is shut down and there is no heat demand and 90C is normally when there is HW demand or a lot of CH demand. But it's good to see other temperatures being used too.

  4. #4
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    Excellent work. Are you planning to get these into Domoticz? I have a Vaillant boiler with VR33 etc. and would love to see what the boiler is doing without having to trek up to the loft room every time.

  5. #5
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    My Vaillant boiler's flow set to 70C max and the Opentherm target flow for today.

    Boiler Flow.jpg
    Last edited by bruce_miranda; 16th November 2016 at 12:15 AM.

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    Do you know if this data would be available via an HGI80, or does it need the direct eBus interface?

  7. #7
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    That's actually a good question. The HGI80 should know about anything the evohome system is doing. So if we assume the evohome controller is passing a target value to the OT bridge to pass on to the boiler then it should be available on the HGI80. I know that the OT bridge is being constantly feed the flow and return temperatures by the boiler. But it it passes this information back to the controller I don't know.
    For the moment I took the easiest route. I am taking the data directly from the ebus by listening to the communication between the VR33 and the boiler.

  8. #8
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    Hey Bruce,
    I have a vaillant 637 system boiler. I bought an ebus-USB converter from a company in Germany and am using it, via a Raspberry PI, to monitor flow + return temperatures along with modulation setting, flame/pump/demand flags, pressure and error reporting. It's worked very reliably so far. I'm not using Opentherm - yet.

    I wrote a Python script to poll the values via ebusd and log them, with more frequent logging when the boiler is on - these values are uploaded into Domoticz, along with the information from the HGI80 so I can see everything in one place.

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    I'm logging to both Domoticz and also to Emoncms. I haven't worked out how to graph multiple temperatures on a single graph yet in Domoticz, hence I use the Emoncms.

  10. #10
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    Quote Originally Posted by jdp80 View Post
    Hey Bruce,
    I have a vaillant 637 system boiler. I bought an ebus-USB converter from a company in Germany and am using it, via a Raspberry PI, to monitor flow + return temperatures along with modulation setting, flame/pump/demand flags, pressure and error reporting. It's worked very reliably so far. I'm not using Opentherm - yet.
    If you bought one of the ebus-usb converters that you should be able to tell the boiler what flow temperature you need. You may not even need Opentherm. You could use Domoticz to set the flow temperature based on the heat demand that you see coming via HGI80 and other variables. For me unfortunately, I built a very simply read only interface, so I can only listen to what the boiler is saying. I have to rely on the OT bridge doing the best job. Now that I've watched it for two days I don't like the fact that the OT bridge runs quite a lot at full wack 90C too often.

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