Modify CH flow temperature by an offset

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eustilou
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Modify CH flow temperature by an offset

Post by eustilou »

Hello, I'm interested to modify the CH flow temperature commanded by the thermostat by a certain offset.

For example, if I set the offset = 10 and the thermostat commands a flow temperature of 35 degrees, I'd like to modify it to 45 degrees.

Can a OTGW do this? I reviewed the OTGW documentation on the website but it wasn't clear to me whether this is possible.

I would also like to be able to adjust this offset parameter from my phone through the cloud. I've seen that there are multiple applications that can be interfaced (Home Assistant, Domoticz, Thingspeak, others?). I understood that data can be pushed from the OTGW into the cloud, but I wasn't clear whether these cloud apps can also be used to write data into the OTGW in order to modify parameters like the offset I am interested in.

thank you
hvxl
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Re: Modify CH flow temperature by an offset

Post by hvxl »

That's a very unusual thing to want. So no, the OTGW doesn't have a feature to do that. It does allow you to set the control setpoint. But because the serial data takes some time to transmit, you won't be able to send the command in time to modify the control setpoint being sent to the boiler based on the setpoint just received from the thermostat. So you will always be one cycle behind. But I don't expect that to make a big difference.

If you do want the offset to be applied immediately, you will have to add it to the firmware yourself. The sources are available.
Schelte
eustilou
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Re: Modify CH flow temperature by an offset

Post by eustilou »

I think it's a feasible solution to send a CS command right after I see a CS command from the thermostat.

How much of a delay are you referring to?
hvxl
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Re: Modify CH flow temperature by an offset

Post by hvxl »

As you will always be one cycle behind, the delay depends on how frequently your thermostat sends MsgID 1. Most thermostats send a control setpoint every couple of seconds.

You can also switch to the interface firmware. In that case the OTGW reports what the thermostat sent and then waits for instructions on what to send to the boiler. This will allow you to modify the control setpoint immediately. But it means you have to do handle every message in your own code.
Schelte
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