Just a quick point to add. My data is captured at 3 minute intervals so it's possible the boiler fires for shorter periods than that and I'm not picking it up. It still doesn't manage to hold the 47C...
Type: Posts; User: Vikings
Just a quick point to add. My data is captured at 3 minute intervals so it's possible the boiler fires for shorter periods than that and I'm not picking it up. It still doesn't manage to hold the 47C...
I've noticed some slightly unusual behaviour from boiler and I'm puzzled. It seems to work reasonably well - especially at the higher end of the temperature range. Let me explain what I did.
I was...
Thanks for that. It worked perfectly! Now operating over the full range of temperatures.
I've swapped over to using the Opentherm feed temperature control now and it seems to run pretty well. One thing I've noticed is the boiler doesn't seem to want to run a feed above 65C. If I set the...
Here is a picture of this morning's heating. I'm much happier with that now. It seems to bring the feed up to around 65C and then holds it there as long as the demand stays on.1962
Yes - that's exactly what I've built into my algorithm. Thanks.
I see. Thanks. I don't have the VR65 or anything like that. It looks like it's reaching my target temperature ok when heating HW so hopefully I'll be fine keeping the same settings.
Interesting. I'm risking going off on a tangent here but I'm curious about the HW heating mode. My boiler doesn't appear to have any connections that would tell it whether it's in HW heating mode but...
I've adjusted d.0 to 18 now. Looking at the temperatures over the past couple of days I get the feeling it is holding the higher temperature better. I'll do some checks later in the week when it's...
It's difficult to answer that as I'm not sure how to tell the difference. I see the boiler putting out a low modulation level and the result of that is a very slow increase in flow temperature. As...
I presume d.40 and d.41 will be the values I'm reading from the Opentherm interface. If so then I am comparing them. They do broadly align with a lag between them. Your comment did make me wonder...
I don't have any outside temperature sensor on the boiler. I do have external temperature available to my server but at present I'm running a pure proportional-integral control loop that is targeting...
OTB?
I have an Arduino with an Opentherm interface on it that talks to the VR33. My server sends the target level (and switches a relay for demand on/off) to the Arduino and also log the data values...
I'm reading status, modulation level, feed and return temperatures from the Opentherm interface (VR33).
I'll have a go with 18 and see what happens.
Thanks.
I've tracked the behaviour over several days now and it generally seems to start up slowly and the modulation level jumps up and down with the feed temperature running in the 40-50C range before...
Thanks. That may not be unrelated. It does sound possible that the boiler is trying to do something like that. It would be useful to have an idea of the algorithms it's trying to apply.
I've noticed recently (but perhaps it has done this for a long time) that my boiler seems to modulate down to a lower flow temperature than the target that I have set. I noticed this early in the...
I've confirmed it's working correctly now. Sending the STATUS message with ch_enable set to 1 is what it needed. The demand control into terminal 4 is working fine alongside the OpenTherm temperature...
I've just spotted an error in my code. I was sending the SLAVE_CONFIG message instead of STATUS. I'll give it another try later and hopefully that might fix the issue.
Do you think I need to do anything with terminals 7-8-9 on my boiler? At the moment there is nothing connected but I wondered if I need to loop any of these to make it fire up.
Just to be clear that's the 'terminal 4' demand signal.
I've been trying this out but I'm having some problems.
Whilst the loop is applied to the VR33 OT connections then the boiler works fine in response to the 240V demand signal as it always did.
When...
No I'm using it to generate OT messages into the boiler (VR33 interface) e.g. set feed temperature and also to query data e.g. feed and return temperature. So it's acting instead of a thermostat.
I'm just using the circuit shown here https://ihormelnyk.com/Content/Pages/opentherm_adapter/opentherm_adapter_schematic_o.png and also the same here...
I've built up my own revised board now with the 'correct' optocouplers and it now works perfectly!! I can set the boiler temperature and read back some data e.g. feed and return temperature.
Just...