Controlling a boiler the Control Setpoint

This Forum is about the Opentherm gateway (OTGW) from Schelte

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algol
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Controlling a boiler the Control Setpoint

Post by algol »

Hi all,

WIth winter approaching I have finally taken some time to investigate why I’m not able control my room temperature with my OpenTherm gateway.

Boiler: Hoval TopGas Comfort 15kW
Theromostat: Hoval TopTronic RS-T (RS-OT)
OTGW firmware: 3.4

The control setpoint of above Hoval boiler is actually driven by the RS-OT thermostat. Unlike many other boiler the thermostat is not sending a room setpoint to the boiler control which then calculates the boiler control set point (so heating circuit hot water temperature). The thermostat uses the thermostat room setpoint, the external temperature (coming from the external sensor connected to the boiler control and sent via OT to the thermostat) and the heating curve (which is selected on the thermostat) to calculate a boiler control setpoint. The control boiler setpoint is sent to the boiler via OT.

12:20:34.718596 T90012C33 Write-Data Control setpoint: 44.20
12:20:34.825464 B50012C33 Write-Ack Control setpoint: 44.20

This means that with current OTGW firmware, I’m not able to control anything (aside from DHW).

Has anyone else the same time of regulation on their boiler?

Schelte, would it be possible to implement an additional command to set the boiler control setpoint? My homework then to emulate the correct calculation logic of the control set point...

Arnaud

Code: Select all

12:20:30.550021 T907C024D Write-Data OpenTherm version Master: 2.30
12:20:30.632969 B507C024D Write-Ack  OpenTherm version Master: 2.30
12:20:31.560199 T107E0118 Write-Data Master product version: 1 24
12:20:31.663844 BD07E0118 Write-Ack  Master product version: 1 24
12:20:32.612990 T10800000 Write-Data Message ID 128: 0
12:20:32.671801 BD0800000 Write-Ack  Message ID 128: 0
12:20:33.665351 T00000300 Read-Data  Status: 00000011 00000000
12:20:33.739571 BC000030A Read-Ack   Status: 00000011 00001010
12:20:34.718596 T90012C33 Write-Data Control setpoint: 44.20
12:20:34.825464 B50012C33 Write-Ack  Control setpoint: 44.20
12:20:35.770669 T90020016 Write-Data Master configuration: 00000000 22
12:20:35.898327 B50020016 Write-Ack  Master configuration: 00000000 22
12:20:36.822440 T00030000 Read-Data  Slave configuration: 00000000 0
12:20:36.881744 BC0031908 Read-Ack   Slave configuration: 00011001 8
12:20:37.875614 T00050000 Read-Data  Application-specific flags: 00000000 0
12:20:37.979024 BC0050000 Read-Ack   Application-specific flags: 00000000 0
12:20:38.927924 T00060000 Read-Data  Remote parameter flags: 00000000 00000000
12:20:39.058108 B40060301 Read-Ack   Remote parameter flags: 00000011 00000001
12:20:39.980944 T900E6400 Write-Data Maximum relative modulation level: 100.00
12:20:40.526278 B500E6400 Write-Ack  Maximum relative modulation level: 100.00
12:20:41.033024 T10101800 Write-Data Room setpoint: 24.00
12:20:41.136939 BD0101800 Write-Ack  Room setpoint: 24.00
12:20:42.090059 T00110000 Read-Data  Relative modulation level: 0.00
12:20:42.217293 BC0113900 Read-Ack   Relative modulation level: 57.00
12:20:43.143293 T10140C0B Write-Data Day of week and time of day: Unk 12:11
12:20:43.222014 BD0140C0B Write-Ack  Day of week and time of day: Unk 12:11
12:20:44.190537 T1015091D Write-Data Date: 9 29
12:20:44.299443 BD015091D Write-Ack  Date: 9 29
12:20:45.316778 T901607DD Write-Data Year: 2013
12:20:46.101525 B501607DD Write-Ack  Year: 2013
12:20:46.421619 T1018114C Write-Data Room temperature: 17.30
12:20:46.437549 BD018114C Write-Ack  Room temperature: 17.30
12:20:47.347399 T80190000 Read-Data  Boiler water temperature: 0.00
12:20:47.455686 B40192C80 Read-Ack   Boiler water temperature: 44.50
12:20:48.400382 T801A0000 Read-Data  DHW temperature: 0.00
12:20:48.485135 B401A2AB3 Read-Ack   DHW temperature: 42.70
12:20:49.452431 T001B0000 Read-Data  Outside temperature: 0.00
12:20:49.514878 B401B0DDE Read-Ack   Outside temperature: 13.87
12:20:50.552077 T801C0000 Read-Data  Return water temperature: 0.00
12:20:50.614961 B401C27CC Read-Ack   Return water temperature: 39.80
12:20:51.560055 T00300000 Read-Data  DHW setpoint boundaries: 0 0
12:20:51.628009 BC0303C05 Read-Ack   DHW setpoint boundaries: 60 5
12:20:52.609735 T80380000 Read-Data  DHW setpoint: 0.00
12:20:52.707420 B40380A00 Read-Ack   DHW setpoint: 10.00
12:20:53.668569 T00390000 Read-Data  Max CH water setpoint: 0.00
12:20:53.773390 B40394600 Read-Ack   Max CH water setpoint: 70.00
hvxl
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Re: Controlling a boiler the Control Setpoint

Post by hvxl »

To my knowledge it's always the thermostat that calculates to what temperature it wants the boiler to heat the water and then sends that to the boiler in the Control Setpoint message.

For manipulating the control setpoint, check out the CS command introduced in the alpha/beta firmware.
Schelte
algol
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Joined: Wed Jul 31, 2013 5:31 pm

Re: Controlling a boiler the Control Setpoint

Post by algol »

Hmmm, then I'm missing something. My understandings was that the OTGW was intercepting the messages form the thermostat to the boiler and replacing these messages with overrides.

Looking at all the posts on this forum and your interesting OTGW site, I thought I understood that the room setpoint was the message that was "intercepted". Or is it that the OTGW is calculating the control setpoint?

i'm missing something,,,

Any way, Imuch appreciate you help!

Algol.
algol
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Posts: 10
Joined: Wed Jul 31, 2013 5:31 pm

Re: Controlling a boiler the Control Setpoint

Post by algol »

Installed beta 8, CS command works great, and error 01 (coming from beta 6 I think) dissappeared.

if anyone can enlighten me, I would still like to know how most of you override your boiler control temperature without the CS command introduced in 4.0.

Anyway, Schielte, you win a stay in my mountain house (as soon as i've finished my renovation). While us Swiss are supposedly built to withstand cold temperatures, I hate getting to my house on Friday night at 11 degC :(

Algol
hvxl
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Re: Controlling a boiler the Control Setpoint

Post by hvxl »

Algol,

Be careful with handing out such prizes, I might just take you up on the offer!

The "normal" way the opentherm gateway works is with thermostats that periodically send MsgID 9, asking for a remote setpoint override. The gateway sends the desired setpoint back to the thermostat. The thermostat then takes that setpoint and the current room temperature and determines a control setpoint to send to the boiler.

So, the gateway doesn't actually modify the opentherm message that the thermostat sends to control the boiler. It just changes the setpoint on the thermostat, just like the program in the thermostat would do, or a user pushing the + and - buttons on the thermostat.

That way the thermostat is utilized to do all the clever things like adapting to the heating characteristics of the house that the thermostat manufacturers have spend many man-hours on to work out.
Schelte
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