Keep the thermostats at the Setpoint instead of 8 degrees

Posted on
Mon Jan 11, 2021 1:49 pm
Stoutjesdijk offline
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Keep the thermostats at the Setpoint instead of 8 degrees

Hi all,

I thought is was possible to adjust the behavior of the thermostats once the temperature matches the setpoint. Right now, my Spirit thermostats go all the way back to 8 degrees. That's a pain, because you need to 'scroll' all the way to 21 or whatever when you want to adjust.

For the life of me, I cannot find where to set that behavior. Is it in TRV? Thermostat? Valve? Raw Z-Wave?

Best regards,

Mark

Trying to tie it all together...
| Indigo 7.5 | Plex | NAD M33 | LG | Panasonic | GlobalCaché GC100 | Sonos | Nest |

Posted on
Mon Jan 11, 2021 3:13 pm
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Re: Keep the thermostats at the Setpoint instead of 8 degree

I am not clear if the issue you are describing is when you are using the TRV Controller to control the Spirits?

Posted on
Mon Jan 11, 2021 4:09 pm
Stoutjesdijk offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Hi Jon, yes this happens with many Spirit stats, but I don't think all of them. I control every thermostat through TRV.

Best regards,

Mark

Trying to tie it all together...
| Indigo 7.5 | Plex | NAD M33 | LG | Panasonic | GlobalCaché GC100 | Sonos | Nest |

Posted on
Tue Jan 12, 2021 3:21 am
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Re: Keep the thermostats at the Setpoint instead of 8 degree

I think that is how the TRV Controller plugin is currently designed to work.
Once setpoint is reached, the Spirit is switched off. This is to make sure that if other radiators are calling for heat, that the one that has reached setpoint doesn't still continue heating if the valve is still partially open.

I will add this to the list of thinks to consider as to whether it can be improved. :)

Posted on
Tue Jan 12, 2021 1:14 pm
siclark offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Why are you controlling the temperature on the Spirit TRV? You should be using the thermostat device from the plugin. That way you set set points to be say 21 when you want warm room and 16 to turn off heat demand but you only need to scroll from 16 to 21 to turn heat on.

Posted on
Sat Jan 16, 2021 9:21 am
Stoutjesdijk offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

That's what I meant -- through the TRV plugin. So I change the setpoint in the TRV plugin device, not the Spirit stat device itself.

Regarding the way that the plugin works, my (too?) simple understanding of the controller plugin is this:
1. I define a heating setpoint in the TRV controller device,
2a. If the setpoint is higher than the currently measured stat temperature (or remote temperature), the plugin requests heat from the source (in my case, it sets a virtual device to TRUE). If every other room was at the desired temperature, the central heating systems changes from OFF to ON,
2b. If the setpoint is higher than the currently measured stat temperature, the plugin opens the valve in a smart way that depends on the temperature delta.
3. While the room heats up and the temperature delta decreases, the controller plugin slowly closes the valve using some algorithm (which/how?),
4a. Once the room is at temperature, the valve should be closed. I assume there is some hysteresis smarts so there might be a time delay, overshoot or both.
4b. Once the room is at temperature, the virtual device that controls the central heating pump turns from ON to OFF (if all other rooms are at temperature)

Is that close to the mark? I could imagine that 4a and 4b do not always happen at the time I described. For example, that the controller plugin uses residual heat from the radiators and shuts down the central heating pump before the measured stat temperature reaches the setpoint.

Thanks, Mark

Best regards,

Mark

Trying to tie it all together...
| Indigo 7.5 | Plex | NAD M33 | LG | Panasonic | GlobalCaché GC100 | Sonos | Nest |

Posted on
Sat Jan 16, 2021 1:19 pm
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Re: Keep the thermostats at the Setpoint instead of 8 degree

The TRV Controller is not that sophisticated. :wink:

The plugin doesn't control the valve; the valve being slowly closed is done by the Spirit as it nears the setpoint. When the setpoint is reached the plugin effectively turns off the Spirit by setting the setpoint to 8 deg C.

If the radiator needs to heat, then the plugin sets the Spirit setpoint to the setpoint + delta. This is to ensure it doesn't switch off before the remote thermostat reaches its setpoint. Typically the Spirit will show a higher temperature than the remote because it is affected by heat from the radiator.

Hope this makes sense? :)

Posted on
Sat Jan 16, 2021 1:26 pm
siclark offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

If you have the TRV SP unadjusted, ie equal to desired SP then the Spiriit will adjust the valve. It will reduce heat as it approaches the SP to avoid overshoot. It doesn’t work well though if you use remote sensor.
Also the Spirit needs to learn so don’t mess with the set point whilst it’s heating.
If you set the spirit TRV SP to be higher than desired using the delta adj then the spirit will aim for say 25 when you want 20 so keep valve fully open for longer as you approach 20 and then Once 20 is hit the plug-in turns effective off the valve by setting SP to 8.
Or you can use lower delta and use combination of both.
If you use remote temp sensor then the TRV will behave unexpectedly as it won’t know the remote temp so will try to set to its local temp. In those circumstances it’s better to use a higher delta.

Posted on
Sun Jan 17, 2021 7:55 am
Stoutjesdijk offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Jon, thanks for your answer but I am still puzzled.

I have variable with the room temperature (float). It is set to 22.0C.
A trigger keeps an eye on that variable, and if it changes, it sets the SP for all Spirits in that room to the value of the variable (22.0 in this case).
However, I see this in the log:
Code: Select all
   Trigger                         HeatSET_BG_changed
   Script                          *** Setting BG TLV setpoints
   Script                          Set BG woonkamer temperature setpoint to 22.0
   Script                          Set BG gang temperature setpoint to 22.0
   Script                          Set BG eetkamer-L temperature setpoint to 22.0 [DIRECT thermostat]
   Script                          Set BG eetkamer-R temperature setpoint to 22.0


So the setpoints of the TRV controller plugins are set to 22.0C. Now, I need to make sure that my central heating thermostat knows that I want it to be 22 degrees somewhere in the house:
Code: Select all
   Script                          *** Setting max requested heat
   Script                          .   Setting maximum heat requested to 22.0
   NEST Home                       sent "NEST thermostat" change heat setpoint to 22.0


So far so good, but then something tells the "woonkamer" (living room) Spirit to change the setpoint to 27 degrees! Is that the controller plugin? I have no trigger or schedule that does so (as far as I know :roll: ).
Code: Select all
   Z-Wave                          sent "BG Gang Thermostaat" change heat setpoint to 22.0°
   Z-Wave                          sent "BG Woonkamer Thermostaat" change heat setpoint to 27.0°
   Z-Wave                          sent "BG Eetkamer Thermostaat R" change heat setpoint to 22.0°
   Z-Wave                          sent "BG Gang Thermostaat" raw command [40 01 1F]

Best regards,

Mark

Trying to tie it all together...
| Indigo 7.5 | Plex | NAD M33 | LG | Panasonic | GlobalCaché GC100 | Sonos | Nest |

Posted on
Sun Jan 17, 2021 8:07 am
siclark offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

You are going to have problems if the Nest that is controlling the boiler is only set to 22. What if it’s temperature reaches 22 before the spirits do? The spirit valve will be open but no hot water will be flowing. The spirit will therefore learn that it takes a long time to heat that room. But then next time when there is hot water, it might over shoot.

You presumably have the delta set to 5. This means the plug-in sets the spirit to 5 more than desired to get fastest heating, and less reliance on the smarts of the spirit, and when the reported temp, from spirit or remote, as set in plugin, is reached, the plugin will set the spirits to 8.

Btw you don’t need code to turn on your nest, the plugin will control a variable and you can just have a trigger pointing to that.

I set the actual thermostat, ie equivalent to your Nest to 28 to ensure it always delivers hot water, and use either Spirits or normal adjustable TRVs to limit actual temperature in each room/radiator.

Posted on
Sun Jan 17, 2021 9:47 am
autolog offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Simon has answered your question better than I would have likely done. :)

The TRV plugin expects the boiler controller to act like a relay. If it is ON (Calling for heat) it is because one or more of your radiators wants hot water. Likewise if it is off, it is because no radiator is calling for heat and therefore the boiler can switch off.

Posted on
Sun Jan 17, 2021 10:04 am
siclark offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Ha, thanks Jon.
To summarise (hopefully)

If you have lots of other radiators in the house with spirits I suggest you set a high delta and use them as on/off devices, ie little time with partially open valves.
It still ideally needs boiler to be on delivering hot water whole time it needs heat which is not guaranteed with your Nest set to same SP

Also if you use remote temp sensors you need to do this.

The only way to use them with their smart partially open valve is to ensure water flows for longer time than usual which will heat other radiators and rooms excessively.
If you have lots of them, or have other rads with adjustable TRVs then you can do this, but you’ll likely need to set the Nest temperature to higher than you need to ensure it doesn’t switch off.

Posted on
Tue Jan 19, 2021 11:25 am
Stoutjesdijk offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

Thank you both! Simon, indeed there is a problem if the room with the NEST is already warmer than the temperature requested by another room. That's why in that case I set the NEST to the max requested heat in the entire house, plus one degree. I left that out previously for the sake of simplicity. All thermostats in my house are Spirits, btw.

When you talk about setting a "delta", which one do you mean? The thermostat offset temperature or something more fancy? I see in my graphs that eventually, the room temperatures reach those of the thermostats. So I would prefer to not adjust the thermostat offset because that would eventually result in too high a temperature in the rooms.

Something else. I notice that it takes a loooong time to heat larger rooms. This seems to be caused by valves that reduce too early. I am thinking about logic (through Indigo) to add 2 degrees when heat is needed, and then reduce that in 1 or 2 steps once the temperature gets close to what is desired.

Best regards,

Mark

Trying to tie it all together...
| Indigo 7.5 | Plex | NAD M33 | LG | Panasonic | GlobalCaché GC100 | Sonos | Nest |

Posted on
Tue Jan 19, 2021 11:33 am
siclark offline
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Re: Keep the thermostats at the Setpoint instead of 8 degree

by delta we mean the Remote Delta Max. This is only enabled when you have a remote thermostat (I thought it was enabled by default)

So one option for you as you have a temperature sensor in the room with the 2 radiators is to use that sensor as the remote for both plug in devices. Set the Remote Delta Max to 5. If you want the room at 21, the plugin will set the TRVs to 26, which will ensure they stay at 100% for longer, and then when that sensor shows 21, the plugin will set both TRV setpoints to 8, so they will close.


I have same as you, a smart thermostat that controls the boiler, and I just set to 28 whenever the variable is set to call heat. Saves for any issues when its temp might be above the highest currently called for heat and guarantees any rad that wants heat gets it. I can see cases with yours where the room the Nest is in is currently at 22, and then all rads are off, but you then set a radiator to 20. Your Nest wont turn on.

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