19C seems pretty cold to me... ?Originally Posted by clarkie
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.
The way the temperature is rounded and biased for display is the way Evohome has always done it, and the way the devices like radiator controllers and remote wall sensors do it. As those can't have their firmware updated there's nothing that can really be done about it, certainly not in a firmware update to the Evotouch itself, which is the only device in the system which can be updated.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; 13th November 2020 at 10:22 AM.
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.
For well organised households that follow a regular schedule of activities, this is undoubtedly the best way to operate any heating system and especially one, like EvoHome, that learns. However, there are less organised households that use different rooms at different times, have unpredictable levels of activity at different times and differing levels of occupancy from hour to hour and day to day, etc, etc. For these unavoidably disorganised households a totally fixed schedule simply is not appropriate and regular manual changes are inevitable.
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.
If they were to remove the 0.5C bias towards the set point from the temperature displayed on the controller (and phone app) which they could certainly do, all the other devices like HR92 and DTS92E would continue to show the "fake" temperature and would then show inconsistent results from the controller, so I'm guessing they just wouldn't want to do that.
In a "single room zone" (the default unless you changed it) the temperature comes from whatever device is set as the sensor for the zone, (remote sensor in your case) and is transmitted to the Evotouch periodically, (how often depends on the device and whether the temperature is changing quickly) and then it is periodically re-sent out to all the HR92's in the same zone by the controller, about every 3 1/2 minutes.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; 13th November 2020 at 04:19 PM.
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
Hi Spence, welcome to the forum. If there is no boiler control, what is firing the boiler? Is it the micro switches in the zone valves? I would say now a BDR91 for boiler control is worth considering.
Cheeky PS. PM me, if you want a BDR91 for cheaper than £60.
Haha, thanks for getting back so quickly and your kind offer.
Both BDR91s can currently fire the boiler up independently as demand in their zone is required.
From a separate thread on here it seems like you remove the orange wires from the 2 existing BDR91s which means that they only operate the two port valves and not the boiler. Then you add the 3rd bdr91 so that it just operates the boiler.
As some of the functions I used to have have disappeared in the current setup I think I'll grab a third BDR91.
PS, the beta is working well here.
Thanks
The orange wires have to be removed from the boiler and not the BDR91. It's the orange wires from the zone valves that are currently firing the boiler. You don't want that to happen.
If you are fully zoned on all rads you could choose to leave the CH valve open manually then clear and rebind its BDR91 as a boiler relay. You would not be able to prioritize DHW if you do this (and I am getting more convinced that this is the best DHW control option with every stored hot water system I see convert) so I would recommend taking Bruce's offer... I may know where he got the spare BDR91 from
Regards AtM
Resideo employee. Comments are personal, and likely to get a hard stare from Rameses
I seem to have a stock of BDR91s because of all the wall sensors I have and these come bundled with them.
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