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Some Worcester Bosch boilers do not report water pressure #212
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If pressure is still available to the bus, then why has it been removed from telegram 0x18? Assuming that pressure is available to a precision of 0.01 (as it is on another boiler I own, an Intergas Eco RF 36), then that data would no longer fit into a single byte - so it would have to have been moved to another telegram. I have looked at my system via Supposing the new telegram is only available polled, rather than periodically broadcast to the bus... ... then the system would be behaving as seen. Next steps Collate a list of such boilers:
Prove that a digital pressure is available to the EMS bus:
Identify this new telegram, and poll it. |
The system pressure in the UBA Monitor Fast (0x18) telegram shows a value 0xFF meaning "not available" on some Worcester model boilers. It is available on a Bosch Condens GC9000iWM for example but not all the Worcester Greenstars. Likewise Boiler Temperature and Boiler Return Temperature are not always available on both these models. I expect the data is somewhere in a separate telegram but without details it will be hard to find as none of this EMS protocol is publicly available. What you could try is capture all the logs from the Boiler with one Pressure setting, then up the Pressure setting and capture a new set. Then painstakingly going through all the telegrams looking for possible changes. |
As a trial, I have done this via a I did not find anything, but will do 24 hours & have another go. But this is why I suspect a polled telegram rather than a (periodic, or event-driven) broadcast telegram. |
One question, Can you see the pressure value in a menu on the thermostat ? |
I have a Worcester Bosch Greenstart 27i System Compact (GC No. 41-406-58)... From the
... and from the
|
My two WB boiler appear/behave identically. They have an analog pressure dial, and no pressure is available via the digital display. However, from their manuals, there is a clear indication of water-pressure error codes, so I still suspect it's a matter of working out what telegram to request. |
I think a lot of WB boilers have no water pressure sensor at all. I have a Greenstar 24i System ErP and added a Sense II to it. The Sense II constantly complained that the water pressure sensor was faulty. Bosch came and changed the HCM (heat control module) in the boiler for a later software version and the problem went away. Looking inside, there's no sensor fitted, so the boiler relies on an analogue pressure gauge and that's it. |
Hello @proddy . As you know I have exactly the same Boiler/Sense II combination as @glitter-ball. When I saw the above I also checked and the only pressure sensor is connected to the front panel gauge by a length of black capillary tube. I would suggest that this issue can be closed next time you are doing house keeping. |
great! thanks, forgot about this one. |
Bug description
My combi boiler does not report water pressure via ems-esp. Notably, all other values appear valid (that is, the remainder of telegram 0x18 is as expected).
My boiler is a Worcester Greenstar 30Si NG, but other Worcester Bosch boilers appear to be affected.
Although this boiler has an analog display for pressure and a digital pressure is not available via the built-in controls, there is good evidence that the system has a digital pressure internally that is available to the bus.
Steps to reproduce
Via telnet, enter the
info
command:Expected behavior
Screenshots
With
log v
, we have:Note that the 22nd data byte is 0xFF (missing).
Device information
Via telnet, enter the
system
command:Note that my boiler requires (at least) version 1.9.2 of the firmware.
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