OTMonitor causing DHW error (Remeha Tzerra)

[jeroen__online]

Hi,

I've been using my OTGW for over a month now, my setup is as follows: (pre-built) OTGW is connected in between my Remeha Tzerra (Plus) and iSense thermostat, positioned right next to the boiler and connected to a Raspberry Pi through USB. Everything is up-to-date, running v4.2 of the firmware and otmonitor. OTMonitor on the Pi is acting as a relay for another OTmonitor instance on my server, which I use to store the logs and override the temperature if desired. The Pi is connected through WiFi, my server through Gbit ethernet, both are connected to my Experiabox (modem/router).

It's been running very nicely over the past month: temperature override is working fine, I'm able to set the outside temperature on the iSense, graphs are properly displayed and no errors are reported. A couple of weeks back the first error occurred when I wanted to take a shower in the morning: the boiler heated up for a minute, but the water turned cold again. Waiting a few minutes seemed to resolve the issue, but what I saw in the otmonitor graph (through the web interface) was that the "boiler water temperature" rose to about 100 degrees when I turned on the shower, then dropped to below 40 and, remarkably, my attempts to turn on the shower again in the minutes after the error occurred were not detected as DHW taps (so the flame stayed off). About a week later it happened again and I was able to have a look at the error code the boiler showed: green blinking LED indicating "error 6", which means the boiler encountered an error and is trying to resolve it. I had my Pi disconnected for a couple of days (for maintenance, the OTGW was still connected though) and the issue didn't occur.

In the mean time I reconnected my Pi to the OTGW and last week the error happened again, but waiting a few minutes didn't seem to help (or I was too impatient), so I stopped otmonitor on my Pi: that instantly resolved the issue. Yesterday, I was able to verify this with full logging: the boiler heated up to about 100 degrees, my DHW taps a few minutes after the error were not detected and right after I stopped otmonitor on my Pi, it was working fine again.

So, my own thoughts on this:

• Because the OTGW was physically connected the whole time, I don't think the problem is in the OTGW or firmware
• The problem only seems to occur when otmonitor is running and does not happen every time I use DHW; it only seems to occur when otmonitor is running for some time (I'd say about a week, I hardly restart my Pi)
• It looks as if the boiler fails to lower the relative modulation level (in time), causing the boiler temperature to rise to about 100 degrees and ending up in an error state.

Schelte, or anyone else, could you shine a light on resolving this issue? Attached are a screenshot of the graph and the logs, I'm happy to provide more info if needed.

Code: Select all

07:31:29.254126  T00110000  Read-Data   Relative modulation level: 0.00
07:31:29.383551  BC0110000  Read-Ack    Relative modulation level: 0.00
07:31:30.256902  T80190000  Read-Data   Boiler water temperature: 0.00
07:31:30.383243  BC01929CA  Read-Ack    Boiler water temperature: 41.79
07:31:31.261386  T00090000  Read-Data   Remote override room setpoint: 0.00
07:31:31.384179  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:31:31.394893  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:31:32.271034  T00630000  Read-Data   Message ID 99: 0
07:31:32.393124  BC0630000  Read-Ack    Message ID 99: 0
07:31:33.269526  T00050000  Read-Data   Application-specific flags: 00000000 0
07:31:33.386656  BC00500FF  Read-Ack    Application-specific flags: 00000000 255
07:31:34.273431  T00000000  Read-Data   Status: 00000000 00000000
07:31:34.392905  B40000004  Read-Ack    Status: 00000000 00000100
07:31:35.278357  T00000000  Read-Data   Status: 00000000 00000000
07:31:35.386476  BC000000C  Read-Ack    Status: 00000000 00001100
07:31:36.283171  T00000000  Read-Data   Status: 00000000 00000000
07:31:36.387701  BC000000C  Read-Ack    Status: 00000000 00001100
07:31:37.289081  T00000000  Read-Data   Status: 00000000 00000000
07:31:37.388575  BC000000C  Read-Ack    Status: 00000000 00001100
07:31:38.292371  T90010800  Write-Data  Control setpoint: 8.00
07:31:38.388874  B50010800  Write-Ack   Control setpoint: 8.00
07:31:39.306230  T00110000  Read-Data   Relative modulation level: 0.00
07:31:39.390154  BC0115C00  Read-Ack    Relative modulation level: 92.00
07:31:40.301203  T80190000  Read-Data   Boiler water temperature: 0.00
07:31:40.393253  B40192E5C  Read-Ack    Boiler water temperature: 46.36
07:31:41.304960  T00090000  Read-Data   Remote override room setpoint: 0.00
07:31:41.397566  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:31:41.408026  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:31:42.312051  T00630000  Read-Data   Message ID 99: 0
07:31:42.403047  BC0630000  Read-Ack    Message ID 99: 0
07:31:43.315083  T001B01E6  Read-Data   Outside temperature: 1.90
07:31:43.408546  B601B0000  Data-Inv    Outside temperature: 0.00
07:31:43.419970  A401B0200  Read-Ack    Outside temperature: 2.00
07:31:44.319050  T00000000  Read-Data   Status: 00000000 00000000
07:31:44.410857  BC000000C  Read-Ack    Status: 00000000 00001100
07:31:45.326987  T90010800  Write-Data  Control setpoint: 8.00
07:31:45.416151  B50010800  Write-Ack   Control setpoint: 8.00
07:31:46.326666  T00110000  Read-Data   Relative modulation level: 0.00
07:31:46.419420  B40115E00  Read-Ack    Relative modulation level: 94.00
07:31:47.331184  T80190000  Read-Data   Boiler water temperature: 0.00
07:31:47.494280  B40193F05  Read-Ack    Boiler water temperature: 63.02
07:31:48.334844  T00090000  Read-Data   Remote override room setpoint: 0.00
07:31:48.496558  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:31:48.508330  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:31:49.340722  T00630000  Read-Data   Message ID 99: 0
07:31:49.497132  BC0630000  Read-Ack    Message ID 99: 0
07:31:50.344697  T900E6400  Write-Data  Maximum relative modulation level: 100.00
07:31:50.497983  B500E6400  Write-Ack   Maximum relative modulation level: 100.00
07:31:51.346687  T00000000  Read-Data   Status: 00000000 00000000
07:31:51.497710  BC000000C  Read-Ack    Status: 00000000 00001100
07:31:52.350576  T90010800  Write-Data  Control setpoint: 8.00
07:31:52.498431  B50010800  Write-Ack   Control setpoint: 8.00
07:31:53.354698  T00110000  Read-Data   Relative modulation level: 0.00
07:31:53.499524  B40115E00  Read-Ack    Relative modulation level: 94.00
07:31:54.358983  T80190000  Read-Data   Boiler water temperature: 0.00
07:31:54.499719  BC0195640  Read-Ack    Boiler water temperature: 86.25
07:31:55.362774  T00090000  Read-Data   Remote override room setpoint: 0.00
07:31:55.501051  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:31:55.511525  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:31:56.367675  T00630000  Read-Data   Message ID 99: 0
07:31:56.533056  BC0630000  Read-Ack    Message ID 99: 0
07:31:57.371398  T90101000  Write-Data  Room setpoint: 16.00
07:31:57.533685  B50101000  Write-Ack   Room setpoint: 16.00
07:31:58.373693  T00000000  Read-Data   Status: 00000000 00000000
07:31:58.537312  B40000004  Read-Ack    Status: 00000000 00000100
07:31:59.377338  T00000000  Read-Data   Status: 00000000 00000000
07:31:59.534968  B40000004  Read-Ack    Status: 00000000 00000100
07:32:00.382177  T00000000  Read-Data   Status: 00000000 00000000
07:32:00.535823  B40000004  Read-Ack    Status: 00000000 00000100
07:32:01.391306  T90010800  Write-Data  Control setpoint: 8.00
07:32:01.482202  B50010800  Write-Ack   Control setpoint: 8.00
07:32:02.393209  T00110000  Read-Data   Relative modulation level: 0.00
07:32:02.485664  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:03.400030  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:03.492494  B401963F3  Read-Ack    Boiler water temperature: 99.95
07:32:04.403508  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:04.495960  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:04.506807  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:05.409157  T00630000  Read-Data   Message ID 99: 0
07:32:05.572429  BC0630000  Read-Ack    Message ID 99: 0
07:32:06.415954  T901810AE  Write-Data  Room temperature: 16.68
07:32:06.572785  B501810AE  Write-Ack   Room temperature: 16.68
07:32:07.419138  T00000000  Read-Data   Status: 00000000 00000000
07:32:07.572895  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:08.422703  T00000000  Read-Data   Status: 00000000 00000000
07:32:08.574062  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:09.428169  T00000000  Read-Data   Status: 00000000 00000000
07:32:09.574638  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:10.434357  T90010800  Write-Data  Control setpoint: 8.00
07:32:10.575383  B50010800  Write-Ack   Control setpoint: 8.00
07:32:11.439019  T00110000  Read-Data   Relative modulation level: 0.00
07:32:11.576274  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:12.444680  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:12.577446  BC0194F0A  Read-Ack    Boiler water temperature: 79.04
07:32:13.448779  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:13.577867  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:13.589497  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:14.454682  T00630000  Read-Data   Message ID 99: 0
07:32:14.578167  BC0630000  Read-Ack    Message ID 99: 0
07:32:15.460641  T80640000  Read-Data   Remote override function: 00000000
07:32:15.578374  B40640000  Read-Ack    Remote override function: 00000000
07:32:15.590123  A40640303  Read-Ack    Remote override function: 00000011
07:32:16.464009  T00000000  Read-Data   Status: 00000000 00000000
07:32:16.579590  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:17.470240  T90010800  Write-Data  Control setpoint: 8.00
07:32:17.582906  B50010800  Write-Ack   Control setpoint: 8.00
07:32:18.474994  T00110000  Read-Data   Relative modulation level: 0.00
07:32:18.581257  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:19.479715  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:19.580793  B40193D6B  Read-Ack    Boiler water temperature: 61.42
07:32:20.484411  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:20.581426  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:20.592793  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:21.493902  T00630000  Read-Data   Message ID 99: 0
07:32:21.582509  BC0630000  Read-Ack    Message ID 99: 0
07:32:22.493721  T00050000  Read-Data   Application-specific flags: 00000000 0
07:32:22.587298  B400501FF  Read-Ack    Application-specific flags: 00000001 255
07:32:23.498884  T00000000  Read-Data   Status: 00000000 00000000
07:32:23.590985  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:24.503953  T90010800  Write-Data  Control setpoint: 8.00
07:32:24.597279  B50010800  Write-Ack   Control setpoint: 8.00
07:32:25.509181  T00110000  Read-Data   Relative modulation level: 0.00
07:32:25.600776  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:26.513439  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:26.605652  B401939F3  Read-Ack    Boiler water temperature: 57.95
07:32:27.517106  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:27.609339  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:27.621823  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:28.523618  T00630000  Read-Data   Message ID 99: 0
07:32:28.687532  BC0630000  Read-Ack    Message ID 99: 0
07:32:29.528415  T001B01E6  Read-Data   Outside temperature: 1.90
07:32:29.688309  B601B0000  Data-Inv    Outside temperature: 0.00
07:32:29.700073  A401B0200  Read-Ack    Outside temperature: 2.00
07:32:30.533113  T00000000  Read-Data   Status: 00000000 00000000
07:32:30.690149  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:31.536765  T90010800  Write-Data  Control setpoint: 8.00
07:32:31.689644  B50010800  Write-Ack   Control setpoint: 8.00
07:32:32.541762  T00110000  Read-Data   Relative modulation level: 0.00
07:32:32.691011  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:33.545899  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:33.691519  BC01939C2  Read-Ack    Boiler water temperature: 57.76
07:32:34.550665  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:34.691955  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:34.705069  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:35.556494  T00630000  Read-Data   Message ID 99: 0
07:32:35.695026  BC0630000  Read-Ack    Message ID 99: 0
07:32:36.559837  T900E6400  Write-Data  Maximum relative modulation level: 100.00
07:32:36.691949  B500E6400  Write-Ack   Maximum relative modulation level: 100.00
07:32:37.563949  T00000000  Read-Data   Status: 00000000 00000000
07:32:37.693573  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:38.569149  T90010800  Write-Data  Control setpoint: 8.00
07:32:38.697692  B50010800  Write-Ack   Control setpoint: 8.00
07:32:39.574062  T00110000  Read-Data   Relative modulation level: 0.00
07:32:39.695242  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:40.580794  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:40.707355  BC01939C2  Read-Ack    Boiler water temperature: 57.76
07:32:41.584071  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:41.696768  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:41.707503  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:42.588777  T00630000  Read-Data   Message ID 99: 0
07:32:42.696795  BC0630000  Read-Ack    Message ID 99: 0
07:32:43.594514  T90101000  Write-Data  Room setpoint: 16.00
07:32:43.697730  B50101000  Write-Ack   Room setpoint: 16.00
07:32:44.597584  T00000000  Read-Data   Status: 00000000 00000000
07:32:44.699248  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:45.603726  T90010800  Write-Data  Control setpoint: 8.00
07:32:45.698394  B50010800  Write-Ack   Control setpoint: 8.00
07:32:46.607196  T00110000  Read-Data   Relative modulation level: 0.00
07:32:46.699392  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:47.619428  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:47.708852  B401939A3  Read-Ack    Boiler water temperature: 57.64
07:32:48.621547  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:48.715200  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:48.726890  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:49.624155  T00630000  Read-Data   Message ID 99: 0
07:32:49.716611  BC0630000  Read-Ack    Message ID 99: 0
07:32:50.629358  T901810AE  Write-Data  Room temperature: 16.68
07:32:50.722551  B501810AE  Write-Ack   Room temperature: 16.68
07:32:51.637849  T00000000  Read-Data   Status: 00000000 00000000
07:32:51.724328  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:52.641785  T90010800  Write-Data  Control setpoint: 8.00
07:32:52.809078  B50010800  Write-Ack   Control setpoint: 8.00
07:32:53.641681  T00110000  Read-Data   Relative modulation level: 0.00
07:32:53.804020  BC0110000  Read-Ack    Relative modulation level: 0.00
07:32:54.646505  T80190000  Read-Data   Boiler water temperature: 0.00
07:32:54.805151  B401939A3  Read-Ack    Boiler water temperature: 57.64
07:32:55.654442  T00090000  Read-Data   Remote override room setpoint: 0.00
07:32:55.808287  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:32:55.817113  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:32:56.657486  T00630000  Read-Data   Message ID 99: 0
07:32:56.807114  BC0630000  Read-Ack    Message ID 99: 0
07:32:57.661851  T00740000  Read-Data   Burner starts: 0
07:32:57.807036  BC0740000  Read-Ack    Burner starts: 0
07:32:58.665424  T00000000  Read-Data   Status: 00000000 00000000
07:32:58.808161  BC0000000  Read-Ack    Status: 00000000 00000000
07:32:59.677179  T90010800  Write-Data  Control setpoint: 8.00
07:32:59.808327  B50010800  Write-Ack   Control setpoint: 8.00
07:33:00.673285  T00110000  Read-Data   Relative modulation level: 0.00
07:33:00.809235  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:01.679539  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:01.810274  B40193966  Read-Ack    Boiler water temperature: 57.40
07:33:02.683537  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:02.811540  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:02.821881  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:03.696281  T00630000  Read-Data   Message ID 99: 0
07:33:03.810514  BC0630000  Read-Ack    Message ID 99: 0
07:33:04.693082  T00050000  Read-Data   Application-specific flags: 00000000 0
07:33:04.811426  B400501FF  Read-Ack    Application-specific flags: 00000001 255
07:33:05.697462  T00000000  Read-Data   Status: 00000000 00000000
07:33:05.813236  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:06.701965  T90010800  Write-Data  Control setpoint: 8.00
07:33:06.814305  B50010800  Write-Ack   Control setpoint: 8.00
07:33:07.712664  T00110000  Read-Data   Relative modulation level: 0.00
07:33:07.814086  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:08.712813  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:08.815960  BC0193907  Read-Ack    Boiler water temperature: 57.03
07:33:09.718122  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:09.814685  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:09.826162  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:10.722382  T00630000  Read-Data   Message ID 99: 0
07:33:10.817549  BC0630000  Read-Ack    Message ID 99: 0
07:33:11.727693  T001B01E6  Read-Data   Outside temperature: 1.90
07:33:11.817853  B601B0000  Data-Inv    Outside temperature: 0.00
07:33:11.830130  A401B0200  Read-Ack    Outside temperature: 2.00
07:33:12.731207  T00000000  Read-Data   Status: 00000000 00000000
07:33:12.822283  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:13.734568  T90010800  Write-Data  Control setpoint: 8.00
07:33:13.826033  B50010800  Write-Ack   Control setpoint: 8.00
07:33:14.737222  T00110000  Read-Data   Relative modulation level: 0.00
07:33:14.829618  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:15.751139  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:15.835770  B401938AB  Read-Ack    Boiler water temperature: 56.67
07:33:16.744842  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:16.836770  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:16.849784  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:17.749762  T00630000  Read-Data   Message ID 99: 0
07:33:17.857159  BC0630000  Read-Ack    Message ID 99: 0
07:33:18.755521  T900E6400  Write-Data  Maximum relative modulation level: 100.00
07:33:20.758176  B500E6400  Write-Ack   Maximum relative modulation level: 100.00
07:33:20.768190  T00000000  Read-Data   Status: 00000000 00000000
07:33:20.768337  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:20.768464  T90010800  Write-Data  Control setpoint: 8.00
07:33:20.922972  B50010800  Write-Ack   Control setpoint: 8.00
07:33:21.765926  T00110000  Read-Data   Relative modulation level: 0.00
07:33:21.924099  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:22.768777  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:22.923806  B4019386B  Read-Ack    Boiler water temperature: 56.42
07:33:23.783258  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:23.928455  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:23.942963  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:24.779342  T00630000  Read-Data   Message ID 99: 0
07:33:24.924633  BC0630000  Read-Ack    Message ID 99: 0
07:33:25.789699  T90101000  Write-Data  Room setpoint: 16.00
07:33:25.933147  B50101000  Write-Ack   Room setpoint: 16.00
07:33:26.787274  T00000000  Read-Data   Status: 00000000 00000000
07:33:26.927068  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:27.799027  T90010800  Write-Data  Control setpoint: 8.00
07:33:27.931423  B50010800  Write-Ack   Control setpoint: 8.00
07:33:28.798080  T00110000  Read-Data   Relative modulation level: 0.00
07:33:28.928402  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:29.800659  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:29.928897  BC019382E  Read-Ack    Boiler water temperature: 56.18
07:33:30.802930  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:30.929946  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:30.940816  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:31.813532  T00630000  Read-Data   Message ID 99: 0
07:33:31.930841  BC0630000  Read-Ack    Message ID 99: 0
07:33:32.812124  T901810B0  Write-Data  Room temperature: 16.69
07:33:32.930835  B501810B0  Write-Ack   Room temperature: 16.69
07:33:33.817586  T00000000  Read-Data   Status: 00000000 00000000
07:33:33.932418  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:34.820863  T100107E6  Write-Data  Control setpoint: 7.90
07:33:34.932638  BD00107E6  Write-Ack   Control setpoint: 7.90
07:33:35.830882  T00110000  Read-Data   Relative modulation level: 0.00
07:33:35.934087  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:36.827182  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:36.934252  BC01937EE  Read-Ack    Boiler water temperature: 55.93
07:33:37.831614  T00090000  Read-Data   Remote override room setpoint: 0.00
07:33:37.935047  BC0090000  Read-Ack    Remote override room setpoint: 0.00
07:33:37.946034  A40091180  Read-Ack    Remote override room setpoint: 17.50
07:33:38.837478  T00630000  Read-Data   Message ID 99: 0
07:33:38.936245  BC0630000  Read-Ack    Message ID 99: 0
07:33:39.848507  T00770000  Read-Data   DHW burner starts: 0
07:33:39.935462  BC0770000  Read-Ack    DHW burner starts: 0
07:33:40.841737  T00000000  Read-Data   Status: 00000000 00000000
07:33:40.936885  BC0000000  Read-Ack    Status: 00000000 00000000
07:33:41.847556  T100107E6  Write-Data  Control setpoint: 7.90
07:33:41.939597  BD00107E6  Write-Ack   Control setpoint: 7.90
07:33:42.849233  T00110000  Read-Data   Relative modulation level: 0.00
07:33:42.943201  BC0110000  Read-Ack    Relative modulation level: 0.00
07:33:43.861014  T80190000  Read-Data   Boiler water temperature: 0.00
07:33:43.946280  B401937B0  Read-Ack    Boiler water temperature: 55.69

[hvxl]

There is not that much related to DHW that can be influenced via the opentherm interface. When there's a hot water request, the boiler just handles that by itself. It doesn't need, or even allow the thermostat to meddle with it. The only thing that can be influenced via opentherm messages is the DHW setpoint. If that somehow got set too high, that might result in a boiler error.

However, I would not expect the Tzerra to accept an invalid value. I also don't see any way that otmonitor would suddenly start messing with that value. And stopping otmonitor would not resolve the issue.

Also, your log doesn't show otmonitor doing anything unusual. In fact, it's only receiving data from the gateway. It's not sending anything back. So, I have a hard time believing these symptoms can be caused by otmonitor.

You indicate that you're only using otmonitor as a relay. It's a bit overkill to use a full-blown application for that. There are much simpler tools to provide the same function. Tools like netcat, ser2net, socat, and others come to mind. You may want to look into those if otmonitor continues to give you problems.

[jeroen__online]

Thanks for your reply Schelte, I've set up ser2net on my Pi now instead of using otmonitor as a relay. I understand otmonitor shouldn't influence the behavior of the boiler because it isn't sending any commands that could cause the error, but somehow it does seem to matter.

I'll report back if the problem occurs again and thanks for looking into it!