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Hi Schelte,

It would be great if it becomes possible to configure a minimum ControlSetpoint.

I have the impression (from gathering.tweakers.net/forum/list_messa ... es/2027810) some thermostats and/or boilers do have an option to configure a minimal CS value, e.g. 40 degrees. Mine (Evohome and Remeha Avanta) doesn't have such option. If Evohome isn't asking heat it sets CS=10, if it's asking heat it can request as low as 32 degrees but in my setup 32 degrees is reached very quickly and the boiler is going to wait until the temperature goes lower than 32 degrees and the return temperature is again lower than the Boiler temperature. With CS=40 this works much better. I did manipulate the CS value with my HA system: if CS is between 10 and 40 I put CS=40 and after 10 minutes CS=0 to check if the Thermostat does still request heat. I did upgrade to FW 5.2 but did downgrade again due to the new timer to reset CS after 1 minute. This would all be solved and direct controlled by the OTGW if it becomes possible to set a low boundary for CS.

P.S.: Thanks for maintaining this great project for already such a long time; I'm using the OTGW already for more than 10 years! In this period I improved the isolation of my home, changed thermostat (Evohome with 8n zones) and replaced my CV by a Remeha Avanta 28C to be able to use much lower temperatures in preparation of a heat pump. It's much more complex to run the system optimal with (very) low heat demand compare to high demand but I like to see this season if I can heat (every room in) my house with temperature of max 45 degrees to be sure I will not get problems installing a heat pump.

You can check in the T1001XXXX report if the thermostat requests heat without the need to execute a CS=0 command.

Do you really want a minimal CS value that will continue to be sent even when you don't need heating? Then the CHenable bit would pretty much function as an on/off control. This is quite an unusual idea that I don't think many other people will use. On top of that, the PIC is pretty much at its resource limits. Adding this as a full fledged feature is unlikely to fit. I suggest you modify the sources and simply hard code the minimum you want. That can be done using much less resources. But obviously that's not going to be something that should be done in the standard firmware that everyone uses.

No, I don't want to always send a minimal CS value, only if the Thermostat is really asking for heat (which means a temperature different than 10 degrees in my case).

I've now build some logic in my HA system (Homeseer) which is working fine with FW 5.1:
if 20 < CS_Thermostat (TX001 message) < 40 degrees AND CS_Boiler !=40 : CS=40 If the Thermostat request a temperature < 40 degrees CS manipulated to 40
if CS_Thermostat (TX001 message) = 10 degrees AND CS_Boiler != 10 : CS=0 This will make sure the Boiler stops heating if there is no request anymore from the Theromstat
if CS_Thermostat (TX001 message) > 40 degrees AND CS_Boiler < 41 : CS=0 If the Thermostat request a temperature > 40 degrees no manipulation required

It would be great to have this in the OTGW as I'm depending on Homeseer now which I don't like that much for crucial functions as central heating. I understand your point it's not easy to give room for this in the firmware. Hopefully we'll get a heat pump installed before the next season and I don't need this anymore.

I'll try with FW 5.2 as well by repeating the CS command before the 1 minute timer expires.

I don't understand what you mean by CS_Boiler. A boiler will normally just acknowledge the control setpoint that it was told. So I have disregarded that part and just made a change for you that adjusts the control setpoint to 40 when the thermostat requests anything between 20 and 40 degrees. See the attached patch and firmware file.

Wow, this is great! I think I wasn’t clear in my explanation, this is exactly what I need! Just tested ik quickly and it seems to work perfectly! I’ll monitor tomorrow if all works well also with start in the morning (when CS is normally slightly higher as 40 degrees).Thanks!

Update: It works very well indeed! In the morning first the Themostat requested 45 degrees, after that it started to ask for temperatures below 40 degrees and the OTGW is requesting 40 degrees.