I’ve seen Opentherm ignore my set flow temperature, and it seems to be when it decides it can’t heat the room to your desired temperature at the current flow temperature.
For example, we have a radiator that is undersized for the room it’s in. The radiator, at a flow temperature of 60 degrees, manages to get the room up to 18.4. If the room thermostat is set at 19.5, once it gets to 18.4 Opentherm will eventually start pushing up the flow temperature in a desperate attempt to do my bidding.
Any chance you have a similar issue? Can you adjust the thermostat down to an achievable temperature?
Edit: this was also causing surprisingly substantial gas use - Opentherm was keeping the ‘heating demand’ percentage at about 55% for just this radiator, all in a doomed attempt to meet the target temperature.
The Drayton is requesting a flow temperature of 90 degrees!
@jamiebennett - Is there a way to limit this as I can’t see how its efficient at all? I’d like to limit the max to 65 or so to keep it condensing as long as possible.
That graph is pretty confusing, is the line that starts at 90 definitely your flow temperature? You have a line that starts at 65 that seems to act like I’d expect the flow temperature would, changing values smoothly rather than with the stepped changes of your 90 line (and it seems pretty clearly limited to 65, like you want it to be).
I solved the problem by setting the relevant thermostat to a temperature it can achieve at the flow temperature I’ve set.
Mine only started gradually increasing the flow temperature after the room temperature had fully plateaued, if yours is jacking the flow right up immediately then it sounds like a different problem.
If you happen to have a Viessmann boiler, you may have stumbled across their non-standard implementation of OpenTherm.
The reason you’re seeing a requested CH setpoint of 90 degrees (or 80 in the case of my boiler) is because the Wiser thermostat sends a request as a percentage of the maximum allowed CH setpoint.
If there’s a larger delta between actual and target room temp, the Wiser hub will request 100%.
Normally the boiler should allow you to set the max CH setpoint using the controls on the boiler itself, but as soon as an OpenTherm interface is connected to the Viessmann boiler, it no longer uses that control to limit itself.
I got around this by using the OTGW to send an OpenTherm message to the boiler, setting a maximum CH setpoint of 55 degrees.
I did speak with Wiser technical support a long time ago about this, but the issue is that Viessmann aren’t following the OpenTherm spec 100%.
I did have to edit and recompile the firmware loaded onto the OTGW in order to enable setting the max CH setpoint, I can look through my files and see if I have any notes or copy of that firmware if needed.
Hi
After much messing with how to install the Wiser intergration must have read so many pages of advice
eventually found this topic and your advice
followed it and it works
many thanks
What particular Intergas boiler do you have? I hear that Intergas has pretty good OT support, so perhaps there’s a less bodgetastic way to adjust max CH setpoint.
Interesting discussion - we have a 1 year old Baxi 600 boiler and it is connected to the wiser hub via the opentherm connections. I have noticed that the LCD on the boiler showing up to around 80c - 85c when the heating is running - I have the temperature dial on my boiler cranked all the way down, since I figured it doesn’t use this to control any temperature when OT is connected - should I be setting this to limit the temperature so it runs more efficiently ?
Also - I have a request for the addon, is it possible to get a ‘climate’ entity that represents the ‘system/hub’ in addition to all the thermostat ones we have already? Where the setpoint would be the away mode setpoint and the hvac modes could represent away, scheduled, boost etc…
If we got this as a ‘dummy’ climate entity it would allow the use of climate cards to easily control away temps etc and boost the entire house. At the moment as they are exposed as entities from a sensor I can’t seem to find a way to get this exposed nicely in lovelace without bodging it.
Log this request on our github and if others want it then they can vote to have it changed. Also, there is a climate template integration in HACs that you could use to do this if it is an edge use case.
Glad you sorted it. We do recommend installing via HACs as it makes it very simple. Can you tell me where you struggled and maybe we can update the docs for others trying to install manually. Thx
The json payload from the hub does have limits. I dont have an opentherm boiler so didn’t know that this could not be set in the app. Also dont know if it does anything. Will investigate if these can be changed on the hub and then those with an opentherm boiler could maybe test if it does do anything.
There will be a release in a few days (bit later than planned due do being away for new year). Will try and include something to test this.
Happy to help with data from Wiser and Viessman integrations.
Having contacted both parties they both say the other party should do it!
EDIT: Having thought about this a bit more, I’m not sure how that Wiser controller can enforce a maximum temperature as it deals in ‘%’ demand. A user above seems to suggest it’s a one-time command to the boiler.
I’ve tried 6 different access points, even going back to Apple AirPort Extreme which usually work with everything.
Every single AP has the same problem. They are all non-mesh, single AP, 2.4GHz.
Within 24 hours, the HubR drops off. Sometimes with a flashing red light, sometimes solid. Sometimes pressing the setup button puts it in to setup mode (flashing green light ), but sometimes it triggers a reboot where you hear the relays click.
The only commonality is HA and so I do think that there must be some sort of resource exhaustion which causes the wireless stack on the HubR to die.
Fingers crossed that the release fixes it once and for all.
