enabling OTC weather compensation using opentherm gateway

[george]

Hello

I am trying to enable weather compensation on my boiler while using otgw from nodo shop.
I an not happy with the way thermostat is running the boiler as it always asks for max temp at the beginning of the cycle and only reduces it by a couple of degrees and the end of them cycle; this is ok when in winter time but bot ideal in sping or autumn and I just don't want to manually adjust the max flow temp all the time.
Boiler manual explains that the feature is disabled when opentherm master device is conected (otgw).
The thermostat has no option to enable or disable but it does request outside temp from boiler (see below log)

I want to know if it can be enabled using a serial command or by manipulating msgid 0.
below a log from otmonitor:

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18:11:56.547526	T001B0000	Read-Data 	Outside temperature (MsgID=27): 0.00
18:11:56.608551	BC01B1700	Read-Ack  	Outside temperature (MsgID=27): 23.00
18:11:57.570537	T80190000	Read-Data 	Boiler water temperature (MsgID=25): 0.00
18:11:57.616797	BC0191A00	Read-Ack  	Boiler water temperature (MsgID=25): 26.00
18:11:58.586664	T10010A00	Write-Data	Control setpoint (MsgID=1): 10.00
18:11:58.633532	BD0010A00	Write-Ack 	Control setpoint (MsgID=1): 10.00
18:11:59.612437	T80000200	Read-Data 	Status (MsgID=0): 00000010 00000000
		   - CH enable: disabled (0)
		   - DHW enable: enabled (1)
		   - Cooling enable: disabled (0)
		   - OTC active: not active (0)
		   - CH2 enable: disabled (0)
		   - Summer/winter mode: winter (0)
		   - DHW blocking: unblocked (0)
18:11:59.675871	B40000200	Read-Ack  	Status (MsgID=0): 00000010 00000000
		   - Fault indication: no fault (0)
		   - CH mode: not active (0)
		   - DHW mode: not active (0)
		   - Flame status: flame off (0)
		   - Cooling status: not active (0)
		   - CH2 mode: not active (0)
		   - Diagnostic indication: no diagnostics (0)
		   - Electricity production: not active (0)

thanks in advance!

George

[hvxl]

The boiler is correct to behave that way. It must follow the instructions of the master. It can only do OTC itself when there is no master. When a master is connected, it is supposed to properly direct the boiler. If you want OTC with a thermostat connected, then you need a thermostat that supports that. There is no way to tell the boiler to disobey the master.

[george]

Hello Shelte and thanks for the reply!

I guessed that would be the way it works and i'm trying to find workarounds.

One solution would be to use an on/off thermostat, but then I loose access to boiler info.
It seems that even when I disconect the OT thermostat and only use the gateway in standalone mode, the result is the same, probably because then the gateway becomes the master (please correct me if I am wrong).

One other weird thing is that the thermostat tries to write relative modulation level and max relative mod level;
the boiler only supports writing of max relative modulation level and only read of relative mod level but weirdly it says unknown data-ID to both requests...any ideea why is that happening?

[george]

here is what I mean:

boiler supported MsgIDs
msgid 17 / Read / Relative modulation level
msgid 14 / Write / Maximum relative modulation level

this is probably the correct answer since msgid 17 is read only:

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10:55:17.188956	T90110000	Write-Data	Relative modulation level (MsgID=17): 0.00
10:55:17.295451	BF0110000	Unk-DataId	Relative modulation level (MsgID=17): 0.00
10:55:18.209211	T90110000	Write-Data	Relative modulation level (MsgID=17): 0.00
10:55:18.324904	BF0110000	Unk-DataId	Relative modulation level (MsgID=17): 0.00
10:55:19.250767	T90110000	Write-Data	Relative modulation level (MsgID=17): 0.00
10:55:19.311768	BF0110000	Unk-DataId	Relative modulation level (MsgID=17): 0.00

on read request the reply is correct (I used AA command):

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10:56:20.681197	T80130000	Read-Data 	DHW flow rate (MsgID=19): 0.00
10:56:20.682223	R00110000	Read-Data 	Relative modulation level (MsgID=17): 0.00
10:56:20.775371	BC0110000	Read-Ack  	Relative modulation level (MsgID=17): 0.00
10:56:20.776480	A70130000	Unk-DataId	DHW flow rate (MsgID=19): 0.00

trying to write doesn't work (boiler manual says it can be written):

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10:56:06.350550	T900E6400	Write-Data	Maximum relative modulation level (MsgID=14): 100.00
10:56:06.397920	BF00E6400	Unk-DataId	Maximum relative modulation level (MsgID=14): 100.00
10:56:07.370824	T900E6400	Write-Data	Maximum relative modulation level (MsgID=14): 100.00
10:56:07.428972	BF00E6400	Unk-DataId	Maximum relative modulation level (MsgID=14): 100.00
10:56:08.398526	T900E6400	Write-Data	Maximum relative modulation level (MsgID=14): 100.00
10:56:08.444796	BF00E6400	Unk-DataId	Maximum relative modulation level (MsgID=14): 100.00

when trying to read using AA comand, otgw sends a write request instead, and the answer is same as above:

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11:07:28.493485	T000F0000	Read-Data 	Boiler capacity and modulation limits (MsgID=15): 0 0
11:07:28.500573	R900E6400	Write-Data	Maximum relative modulation level (MsgID=14): 100.00
11:07:28.587195	BF00E6400	Unk-DataId	Maximum relative modulation level (MsgID=14): 100.00
11:07:28.590137	AC00F241E	Read-Ack  	Boiler capacity and modulation limits (MsgID=15): 36 30