Opentherm + EvoHome + Viessmann 111-W overshoots

[StephenC]

I've now had a written response to the email I sent to Viessmann last week. My previous notes in this thread relating to Viessmann, were phone calls to be clear.


Once again (@Rameses), Viessmann are stating this is a Honeywell issue as the R8810 should not be locking out the onboard boiler controls:


"If the Honeywell control worked fine whilst using the switch live demand through the BDR91 then there is no logical reason why, when connected to the open therm through a R8810 Bridge, this should be any different, the boiler control logic should not be overridden by the Evohome, If the boiler is set to 65 degrees for example then the Evohome should not force the boiler to 81/82 degrees.

We suggest you ask Honeywell if any settings can be made to the Evohome to adjust this issue, potentially, if the boiler is being forced to 82 degrees this is very close to the boiler limit stat and could potentially cause the boiler to lock out and no heating would be available until the boiler is reset.


All of our boilers are fully modulating and have had open therm connection for the past 10 years without any issue.

Kind Regards
Lee Pedley
Viessmann Technical Support"


I still think it's odd that there are 2 users in this thread with a locked out ch flow temp dial, and also the US manual for very similar Viessmann combi boiler explicitly states the control will be locked out..who is right? Hopefully in time we'll find out.

[DBMandrake]

Meanwhile I'm crossing Viessmann off my list of possible boiler manufacturers if I had to replace my boiler.

(Not that I could afford to at the moment! )

[dty]

Meanwhile I'm crossing Viessmann off my list of possible boiler manufacturers if I had to replace my boiler.

(Not that I could afford to at the moment! )

I'm doing mine very soon. I find it odd that the Viessmann 100-series "supports" OpenTherm (apropos this thread), but the 200-series doesn't. Seems like a retrograde step to me.

I'm going for the Vaillant EcoFit Pure. I can't find a single report on the internet about it working with OpenTherm (because it's quite new), but my installer assures me that it's E-Bus compatible and a gray-market VR33 will do the trick... *fingers crossed*

[bruce_miranda]

Having studied the interaction of the VR33 with the boiler, in some detail, I am sure the VR33 will work with any Vaillant boiler. It's just basically an OT to eBUS bridge. The VR33's PCB edge connector may not work but you can easily work around it. Just 4 wires, 2 x power and 2 x eBus.

[StephenC]

Has anyone had a boiler give out a comms error/fault relating to Opentherm?

@ Rameses, Honeywell called today to talk about additional telemetry etc. to be set up to allow monitoring to be more in depth. I'm not sure when that was going to take place.

I'm also unsure if this is a coincidence or not, but either way, from around 4pm this afternoon I noticed my Viessmann 111-W combi boiler showed an "A9" error/fault code as the photo shows:


Boiler Error/Fault code:
Viessmann-A9-Error code.jpg

This is the service manual explanation:

System characteristics:
Control mode without OpenTherm device

Cause:
Communication error, OpenTherm device

Measures:
Check connections and cable; replace OpenTherm device if required.

Error/fault Code Explanation
Error-code-explanation.jpg

Source:

Viessmann 111-W manual:

http://www.viessmann.com/http-svc/web/england/tdis.nsf/0/5C09ED8DD8AB266CC1257BE500340837/%24FILE/Vitodens%20111%20install%20and%20Service%20Manual.pdf

The strange thing is, it all "seems" to be working. DWH still works (that shouldn't be affected by OT anyway due to combi nature), and CH still works (i.e. we are getting hot water into the rads).

The Evohome controller still thinks its connected to the R8810 OT device as the OT device still flashes green every 10 seconds.

The OT still fires up the boiler that I can see when set point changes occur....very peculiar. I cannot see what comms issue there is between R8810 OT bridge and the Boiler if all is working......maybe it is getting messages it doesn't understand from the R8810.


I will ring Viessmann in the morning and see what they have to say. Not a lot I can do as I'm not Gas Safe registered so shouldn't really be opening up the boiler.


UPDATE/RESOLUTION: please see post #62 in this thread

[paulockenden]

Not a lot I can do as I'm not Gas Safe registered so shouldn't really be opening up the boiler.

That's only for the combustions bits, I think.

[bruce_miranda]

Could it have been a comms failure that it has now recovered from?

[StephenC]

Could it have been a comms failure that it has now recovered from?

Doesn't look that way. The error is still flashing now. The boiler comes on every now and again to top up the CH rad water, and also again when hot taps are run.

I've tried the famous turn it all offf and then back on again....no difference though. Very strange.

The CH Flow temp dial is set to "1" which is approx 30-35 degrees C, so it's not even using that as I've seen boiler temps in the 60-70 degrees range. I.e. as if all is actually working ok (except the max temp issue I have that is still ongoing)

I'm also going to call Honeywell as well to see what they say/can assist with.

[StephenC]

I'm seeing the Honeywell R8810 OT Bridge flash RED in the following sequence when A9 is shown on the boiler.

1-Short quick Red LED flash
2-Short quick Red LED flash
3-Short quick Red LED flash

Led off for same amount of time as the red led flashing sequence

1-Short quick Red LED flash
2-Short quick Red LED flash
3-Short quick Red LED flash

Led off for same amount of time as the red led flashing sequence

Etc....


Seems to be intermittent- hence I saw green led flashes every 10 seconds (correct operation) earlier.

I've tried moving the EvoHome controller to within 1 metre of the R8810 OT Bridge and this made no difference.

An RF test does not work even after rebinding (see below), but then I've just read someone else had this problem:
http://www.wordpress-1219309-4387497.cloudwaysapps.com/vbulletin/showthread.php?4109-Honeywell-Evohome-with-R8810-OpenTherm-Gateway

I've then reset the R8810 OT bridge fully via 15 seconds button press, removed and boiler control from system settings, and then rebound.

No difference, so at this point I'm stumped.


I've read the R8810 OT Bridge install guide below, and none of the led flash sequences match that I can tell.

http://www.honeywelluk.com/Documents/Installation-Guide/pdf/50034666-001%20(EN).pdf

[bruce_miranda]

I thought the Red LED flashes meant that there was no OT message received for some time. Hence the bridge was complaining.

[StephenC]

I thought the Red LED flashes meant that there was no OT message received for some time. Hence the bridge was complaining.

I thought that, but I was seeing it minutes after seeing green led flashes....re: red led flashing the PDF says it's after 1 hour comms loss..

[StephenC]

Well, now after rebinding (after clearing the R8810), its no longer switching the boiler on at all for CH..

Edit: the boiler Keeps kicking in intermittently....I'm wondering whether this actually means that since around 4pm today, EvoHome controller or the R8810 OT to be specific actually, is in "fail-Safe" mode of operation since comms has been lost...i.e. 20% on, 80% off

[StephenC]

Well, the house is fairly warm this morning. I can't say I've established what the pattern is that the OT tells the boiler to come on.

I don't think it's fail safe as I'm pretty sure it's not 2 mins on, 8 mins off over a 10 minute period.

It seems random to me at the moment without and data to show when it fired and when it stopped with A9 error, but at least it's generating some heat as I've increased the set points on a load of radiators to allow the HR92 to be open and take hot ch water from the boiler when it does fire up.

I'll be speaking to Honeywell this morning as I suspect it may be due to a modification or logging setup they called me about yesterday, that I gave them permission to carry out. (Although I was told I would get an email to confirm date and time).

There is no comms issue that I can see as the EvoHome controller and R8810 OT bridge bind successfully each of the 3 times I've performed it, and it flashes a lot (7-9) times when performing an RF Heat demand test when the both devices are in their original positions. No additional wireless devices added to the house or any other modifications.

[DBMandrake]

That's only for the combustions bits, I think.

Yes, I believe you're not allowed to tamper with any of the gas pipes/fittings, the gas modulator (whatever it's called) or open the actual firebox or anything that would expose a naked flame. (As you might not seal it up properly gas tight again, which could cause CO leakage)

Other repairs should be fair game though - wiring, temperature sensors, swapping a PCB, water pipe plumbing, circulator pump etc... but don't quote me on that.

[Rameses]

Stephen - As per agreement - please provide feedback to customer services ref your case. The senior tech will pick up with you.

You should have had an email, please check spam etc. But sorry you didnt get the exact timing notification.