2/9/2017 3:56 AM | |
Posts: 8 Rating: (0) |
Hi, Application is Geminox Boiler, LMU64 ver. 3.03. The issue is with modulation instability of the burner. In the attachment, there is graph of values obtain from OpenTherm bus during communication between OpenTherm master (qaa730.110 ver. 1.06) and OpenTherm slave (LMU64). Changing boiler ventilator do not solve the issue. Can it be the result of wrong parameters / fault of LMU64? I noticed, that fan control parameters of LMU64 are described in section "Burner control fan" of LMU64 2.08 documentation, but only few of them can be changed from QAA73, most of them are OEM specific. Or is it known behavior of some fault of LMU64? Thank you for help. Attachmentmodulation_instability2.pdf (1048 Downloads) |
Last edited by: rpav at: 2/9/2017 4:04:56 AMLast edited by: rpav at: 2/9/2017 4:06:02 AM |
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2/10/2017 5:43 AM | |
Posts: 8 Rating: (0) |
Hi Thomas, thank you for your interest. The issue appears in both boiler modes - central heating mode as well as DHW mode. By the term "Modulation instability of the burner" I mean the following observation:
I assumed that there was a problem with boiler fan (ventilator). But as I wrote, changing the ventilator does not solve the issue. Now I'm not sure what is cause and what is consequence. It is clear that the fan speed control is incorrect. Should it be fault of LMU64? Or is there something else on which LMU64 does the decision about fan speed and that is wrong? Unfortunately, there is only very limited information about the process of fan speed calculation by LMU64 (or I haven't the right documentation). That's why I asked here, any suggestion will be very appreciated. Of course I'm ready to answer any question about the issue. Thank you, Roman PS: Attached graph represent the issue even better: the relative modulation (black line) changes quickly from 15 to 27 % and vice versa. It is not expected fan control by LMU64 :( Attachmentmodulace.pdf (1041 Downloads) |
Last edited by: rpav at: 2/10/2017 8:18:55 AM |
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3/24/2017 11:58 AM | |
Posts: 8 Rating: (0) |
2. The attached graph from the same period of time shows that there is no correlation between fan speed and "Process signal segment flow". |
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