If the room wasn't losing heat and it was within 0.2C of setpoint then no thermal input is required.
Evohome firmware 02.00.19.31 Beta Trial - Exclusive for Automated Home Members
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So the display should indicate 17.5C as its over the threshold to call for heat.
So really the rounding applied when you change the setpoint should be applied to the temperature displayed.
So basically I should tell my wife to turn the temperature up by 1.0C to get a radiator to heat up.
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Originally posted by clarkie View PostAnother test today bedroom radiator stone cold. Display indicates 17.0C domoticz indicates 17.3C.
Turn the heat up to 17.5C a few minutes later display indicated 17.5C system summary bedroom requesting 0% heat.
Waited 30 minutes radiator stone cold 0% heat request.
Waited 60 minutes radiator stone cold 0% heat request.
So can you tell me what temperature difference is required to heat the radiator.
Also, I don't think I've seen this discussed before, but when an HR92 goes to 0% valve pin position (fully closed) it goes into a sort of "sleep" mode where it won't produce any heat demand again until the set point is at least about 0.5C above the ambient, when it will "wake up". Whereas if it is already partially open then it will produce heat demand even at the set point.
So you would probably find if you turned it up to 18.0C then waited for it to open the valve, then turned it back to 17.5C it will close the valve a bit but still generate some heat demand. I've long noticed this behaviour (it can cause temperature cycling in low load conditions) but I don't know the reasoning behind why it is designed this way. (Personally I think it's a mistake, but it is baked into the HR92 firmware so can't be altered with an update...)
Is the temperature difference compared against the setpoint and the actual temperature or the "fake" temperature?Last edited by DBMandrake; 12 November 2020, 05:01 PM.
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Originally posted by clarkie View PostSo the display should indicate 17.5C as its over the threshold to call for heat.
So really the rounding applied when you change the setpoint should be applied to the temperature displayed.
So basically I should tell my wife to turn the temperature up by 1.0C to get a radiator to heat up.
However if the radiator is cold and your new set point is still very close to the ambient temperature as in your example, it may not be enough to "wake" the HR92 into opening the valve and calling for heat. In that case you would want to turn it up by 1C to ensure that something happens.
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Originally posted by clarkie View PostIs it possible to have a flame indicator (heat demand) for each zone you would then know if the zone is going to heat 🔥 up.
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Originally posted by clarkie View PostAnother test today bedroom radiator stone cold. Display indicates 17.0C domoticz indicates 17.3C.
Turn the heat up to 17.5C a few minutes later display indicated 17.5C system summary bedroom requesting 0% heat.
Waited 30 minutes radiator stone cold 0% heat request.
Waited 60 minutes radiator stone cold 0% heat request.
So can you tell me what temperature difference is required to heat the radiator.
Is the temperature difference compared against the setpoint and the actual temperature or the "fake" temperature?
AtMResideo employee. Comments are personal, and likely to get a hard stare from Rameses
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Originally posted by clarkie View PostSo the display should indicate 17.5C as its over the threshold to call for heat.
So really the rounding applied when you change the setpoint should be applied to the temperature displayed.
So basically I should tell my wife to turn the temperature up by 1.0C to get a radiator to heat up.
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How this all came about this week we were sitting in our lounge which is normally set to 19.0C during the day. Normally this is OK, but on this occasion it needed to be increased ( radiators were cold) so a small increase was required i.e. 0.5C increase. Turned up the setpoint nothing happened needed to be 1.0C increase to get the boiler to fire up.
In the evening the schedule is set to 20.5C which is fine. During the day we don't normally sit in the lounge for long periods. We are not fiddling.
Todays test highlighted the weird algorithm when you increase the heat by 0.5C the displayed temperature jumps by 0.5C a few minutes later.
In my test the actual temperature was obviously to high 17.3C to actually request any heat. So why doesn't the display actually show 17.5C so that increasing the temp by 0.5C will actually cause a request for heat. I know that the radiator valves will show a different temperature if this software change is made. This is a beta release so input from users should be considered overall this release is much better no overshoot of temperature.
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I have some switches in Domoticz that implement a timed temperature boost in certain zones by requesting a setpoint of 22 deg with a TemporaryOverride with an until-time calculated at 20 mins from now.
It always worked regardless of whether economy mode was set at the controller or follow-schedule was active. That would seem to imply that the 'old' ECO mode did a one-off setpoint drop on selected zones when it was activated, but the controller ignored applying the -3 to any subsequent setpoint changes.
What I've observed lately is that when eco/boost is active in the beta firmware, this behaviour is different and the -3 deg offset is applied to any incoming setpoint requests - even after the initial act of enabling eco/boost mode.
Am I correct in deducing this or is something else playing out here?
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Originally posted by clarkie View PostHow this all came about this week we were sitting in our lounge which is normally set to 19.0C during the day. Normally this is OK, but on this occasion it needed to be increased ( radiators were cold) so a small increase was required i.e. 0.5C increase. Turned up the setpoint nothing happened needed to be 1.0C increase to get the boiler to fire up.
In the evening the schedule is set to 20.5C which is fine. During the day we don't normally sit in the lounge for long periods. We are not fiddling.
Do you use the HR92 as the temperature sensor for the zone or do you use a remote wall sensor like a DTS92E or Y87RF ?
If you're setting the set point lower during the day and higher at night it sounds like you are using just the HR92 as sensor and unwittingly trying to compensate for the inaccuracies of measuring room temperature beside a radiator.
In short, the colder it is outside and the hotter the radiator is, the more you have to increase the set point to maintain the same "comfort" level as the HR92 senses a temperature that is higher than true room temperature when the radiator is very hot.
Conversely when it's warmer outside and the radiator doesn't need to run much or at all the temperature reading at the HR92 will drop below the average room temperature because it is close to the floor and usually near an outside wall. So you then find yourself having to turn it down to avoid heating when you don't need heating.
If you use a remote sensor you will find that you don't need to vary the set point during the day or even with the seasons. We have a DTS92E sensor in the living room sitting near the opposite side of the room and schedule the living room to 21.5C through the whole day on the weekend and mornings and evenings during the week.
We don't change this set point for summer or winter either - with a remote sensor there really isn't any need to, as provided that it is properly positioned in the room it is measuring the true room temperature. In winter it doesn't matter if it's day or not, mild or freezing weather, it maintains a comfortable room without adjustment. And in summer when the room will naturally heat up near this temperature it still turns the radiator off even when set to 21.5C and avoids overheating the room.
Prior to installing the remote sensor we were setting the Living room anywhere between 21C in warm weather and 24C in freezing weather trying to maintain the same perceived level of comfort.
Personally I think a remote sensor is worth it for any room where you spend a lot of time as it really improves temperature control dramatically over using the HR92 as sensor and eliminates the influence of direct radiator heat on the measurement.
Todays test highlighted the weird algorithm when you increase the heat by 0.5C the displayed temperature jumps by 0.5C a few minutes later.
In my test the actual temperature was obviously to high 17.3C to actually request any heat. So why doesn't the display actually show 17.5C so that increasing the temp by 0.5C will actually cause a request for heat. I know that the radiator valves will show a different temperature if this software change is made. This is a beta release so input from users should be considered overall this release is much better no overshoot of temperature.
I don't like it either but I've come to accept that it's just how it works. If I want to get a precise room temperature reading I look at my graphs which use the raw temperature readings.Last edited by DBMandrake; 13 November 2020, 11:22 AM.
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Yes we do have remote sensors.
I would have thought that the evotouch had access to the actual room temperature so apply the rounding to this value and display.
Thanks for explanations guess its not going to happen, mainly because of the discrepancy between the touch and the radiator display.
I guess the evo touch gets the temperature from the valves this is why there's a delay (up to 4min) before the value is shown.
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Originally posted by paulockenden View PostYou need to get past thinking about heating radiators up. Rather than applying overrides, adjust your schedule to get your rooms to be comfortable at the times you use them. That's how Evohome work best - when you're no longer fiddling.
I cannot think of any circumstance where an 0.5 degree change would be appropriate. If I am feeling too cool or warm it would require at least a 1 degree change to make a noticeable difference in comfort level and 0.5 degree changes are only of academic interest. I have never felt the slightest interest in tracking and graphing temperatures. I agree that a separate room thermostat is far superior to relying on radiator valves and I purchased these for most rooms soon after EvoHome was installed.
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Originally posted by clarkie View PostYes we do have remote sensors.
I would have thought that the evotouch had access to the actual room temperature so apply the rounding to this value and display.
Thanks for explanations guess its not going to happen, mainly because of the discrepancy between the touch and the radiator display.
I guess the evo touch gets the temperature from the valves this is why there's a delay (up to 4min) before the value is shown.
Interesting point - if an HR92 is the temperature sensor for the zone it doesn't use the reading directly (unless it is in multi-room mode) it actually sends it to the controller then waits for it to send it back again on the next 3 1/2 minute interval!
This is why even if an HR92 is the sensor for the zone the reported temperature on that same HR92 lags behind that shown on the controller - because it doesn't update its own display until the temperature measurement has done the full round trip from HR92 -> Evotouch -> HR92, and that second hop of the journey only happens every 3 1/2 minutes.
Regarding finding that you need to adjust the set point a lot despite having a remote sensor - it's possible you might need to relocate the sensor. I've tried a few locations in the living room and my preferred location by the light switch near the door close to the main sofa didn't work very well because there is a radiator in the hall on the opposite side of that wall that would skew the measurement of the sensor. Also the thick brick and plaster walls have a lot of thermal mass and seem to add additional lag to the response of the sensor when it is wall mounted. (The reading is influenced quite a bit by the temperature of the wall itself)
I ended up using the stand for the DT92E and sitting it on the corner of the TV cabinet and while I don't like having it "loose" as it's more prone to damage and being knocked over, it controls the room temperature much better from there than being mounted on a thick brick and plaster wall.
For the exact same set point it's quite surprising how different the room feels under different conditions depending on where you locate the sensor.Last edited by DBMandrake; 13 November 2020, 05:19 PM.
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Hi all, first post here but this forum has been a great resource for my evohome setups in the past and after recently moving house my new setup too. I've been able to answer most of my questions with a quick search and have pretty much everything up and running as I want it.
One question I have with regards to this beta (19.33) is that I've got an S plan setup with 2 two port valves each bound to its own bdr91.
In the installer menu I believe that I'm configured correctly with the relevant bdr91 bound only under the stored water setup and nothing set under the appliance control section. Is it correct that in this configuration that dynamic room scaling is not possible, even though a bdr91 is bound to central heating but under the stored water config.
If that's the case then it sounds like the only option to get dynamic scaling is to fit a 3rd bdr91 and have that working independently to control the boiler leaving the 2nd and 3rd bdr91's to control just the valves themselves under stored water. Is that correct? In people's experiences is the dynamic scaling worth the £60 for a new bdr91?
Cheers
Spence
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