Evohome stops heating for no reason or doesn't even start

[emeed]

Hi,
I've seen a lot of topics on evohome overshooting it's SP.
I seem to experience the opposite.
I got an opentherm gateway after the problems started so I could see what evohome sends to my boiler.
It's a combiboiler with integrated pump.

1) Sometimes i ask for heat and it takes an hour before evohome sends the command to my boiler.
On the evohome you can see that it asks 100% for the boiler and 100% for the zone but it does not send anything to the boiler.

2) After a while it stops heating even when the temperature is not reached. (I'm talking about 5°C from the SP, not just 1°C)
As you can see in the image. It started heating for almost exactly 30 minutes, then the flame status was lost for 5 minutes (but the pump still ran apparantly because I started losing temperature immediatly) before finishing off with a 10 minute restart.
It never came on again. It just started doing it's maniacle overtemperature loop.

In the system menu on the evohome it still says 100% at boiler and 100% for the zone.



Anyone ever experienced something like this?
I'm at the end here. I got the data on the evohome and I got the output data of the evohome.
What more can I get to troubleshoot this?


My setup.
Latest evohome wifi with opentherm controller
Downstairs = 6x HR92 controlled by the evohome
Bedroom 1 = 1x HR92
Bedroom 2 = 1x HR92
Bedroom 3 = 1x HR92
Bathroom = 1x HR92
Garage = 1x HR92 (only for temperature measurement really)

[paulockenden]

What's the distance / number of walls between the controller and the Evohome OpenTherm bridge? My first suspicion would be that the signal is marginal and so sometimes isn't getting through.

[emeed]

2-3 15cm walls.
I could test that by using the original thermostat cables and connect the controller closer to the evohome.
I'll try that.

[emeed]

I put the receiver next to the evohome.
Didn't change a thing.

There is this strange periodic occurence that you can see at the start and the end on the image.
Every 15/20/30 minutes the boiler starts ramping up to 60°C (which is 10°C over my max set temperature on the boiler!).
I have no idea why or how and I wonder if it stops the normal programming.

[DBMandrake]

When the Evohome is saying it's calling for 100% heat from the boiler but Opentherm is not firing the boiler, is the light on the OpenTherm bridge on or off ? If it's off, (eg agreeing with the Opentherm logging) that suggests a wireless comms problem from the Evohome to the Opentherm bridge.

[emeed]

Evohome is atm asking for 100% heat and the only thing the bridge does is blinking every 5'is seconds. I've never seen it do anything other. I don't thin it goes full off or on depending on the load
The bridge is right next to the evohome.
I guess I'll have to do a full reset of the system because it's uncontroleable right now, again.

[paulockenden]

Try setting it up WITHOUT otgw in the middle (just connect the wires in a choc-block or Wago). That way you've eliminated one of the variables.

[emeed]

Ok wait. Few clarifications because we're not talking about the same thing.
I only used the gateway to try to understand what's happening.

I put the evotherm directly on the boiler by means of the RF bridge R8810A1018 to do actual testing.
That's why I responded to DBmandrake that the RF bridge blinks green.

[paulockenden]

But OpenTherm Gateway has to sit IN SERIES, between the R8810A1018 and the boiler. Both the bridge and the boiler need to be connected to it.

Is that not how you had it connected? If so, that might account for the problems.

But if you are saying that you have problems whether you have OTGW in series, or with it removed, then the problem obviously lies elsewhere. I was just trying to simplify the setup to eliminate possible sources for the problem.

Maybe someone else has some ideas.

[emeed]

I tested with and without for that reason.

[matchu]

Hi appreciate that this post is old but just wondering if you managed to resolve? I'm trying to get opentherm to work with my boiler (worcester high-low 440) via additional adaptor but behaviour is very similar if not the same as you discribe. It's like it works 80% of the time but then sporadically starts acting weird.

[emeed]

Hi appreciate that this post is old but just wondering if you managed to resolve? I'm trying to get opentherm to work with my boiler (worcester high-low 440) via additional adaptor but behaviour is very similar if not the same as you discribe. It's like it works 80% of the time but then sporadically starts acting weird.

I got a on/off controller and never looked back.