Can an Evohome system be introduced in stages?

[gordonb3]

Sort of, yes. Your input needs to be sent to the HR92 which then in order needs to instruct the BDR91. The delay comes from the fact that the HR92 is not awake all the time but is only available for communication once every ~5 minutes which they did to preserve battery power. The actual time between input and action of course depends on how close or far your timing is from that next time slot.

[therealfronty]

The system seems to work on some kind of cycle and I've noticed things don't tend to happen instantly. I've not timed how long it takes my BDRs to go on and off, although I don't remember it taking as long as "several minutes". Someone else here might be more knowledgeable.

[anniesboy]

Yes quite normal delay is usually around 3-5 minutes,being impatient I have found this a little frustrating

[haggis999]

The delay was a little frustrating while I was trying to test that the BDR91 was responding to my requests via the controller, but such a delay would make little difference to normal system operation.

One of my pet hates is big corporations that make a serious effort to write comprehensive manuals and then don't bother to include an index. Finding things in the Evohome 50-page Installation Guide can be a bit of a challenge. I only found out by trial and error a few minutes ago that the rotary control on the top of the HR92 bound to my active zone (though not yet connected to a radiator) provides another way to override the scheduled target temperature. A change via this knob is then reflected back to the Evohome controller and the Android app.

This has made me assume that the LCD display on the HR92 shows the current target temperature by default. Is there any way to make it show the actual temperature?

[killa47]

This has made me assume that the LCD display on the HR92 shows the current target temperature by default. Is there any way to make it show the actual temperature?

Yes there is. If you read pages 8 & 9 of the user guide for HR92 in the link here: https://www.plumbworld.co.uk/documen...tion-guide.pdf
it explains how you can change the display parameters. Parameter 7 is set to the default of 0 = Set/programmed temperature but if you change setting to 1, this will then display measured room temperature.
Hope that helps.

[haggis999]

Yes there is. If you read pages 8 & 9 of the user guide for HR92 in the link here: https://www.plumbworld.co.uk/documen...tion-guide.pdf
it explains how you can change the display parameters. Parameter 7 is set to the default of 0 = Set/programmed temperature but if you change setting to 1, this will then display measured room temperature.
Hope that helps.

Thanks for that link.

All I got with my pack of four HR92s was a very basic Quick Start Guide, which told me to find out more by finding the full Evohome Installation Guide on the Honeywell website. Neither of those guides makes any mention of the HR92 Installation Guide you referenced! I would probably have spotted this omission earlier if I'd tried to attach an HR92 to a radiator, as I already knew I would have to check valve stroke settings and the Evohome Installation Guide says nothing about that subject, just as it says nothing about HR92 display parameters.

On a different topic, we woke up to a rather cold house at 8:00am this morning. It was only 17.5 degrees, even though the system had been set to turn it up from 15 to 21 at 7:30am, as you can see on the attached schedule, which is the same for every day of the week. I had to manually raise the target to 21 degrees. What might cause such an error? The next scheduled switch (from 21 to 19 degrees at 10:30am) worked fine.

[killa47]

What might cause such an error? The next scheduled switch (from 21 to 19 degrees at 10:30am) worked fine.

Not sure whether you would get a 6 degree C uplift between 7.30 a.m. and 8.00 a.m. but this might depend on the weather outside, the house insulation properties, sizing of the radiator in the room etc.
If you did expect the radiator to output that heat demand of 21C, then something else must be in play.
Our house has 10ft high ceilings and poor insulation (1920s build) so I'm not sure I could guarantee a 6 degree lift in 30 minutes following the overnight setting.

More enlightened members might proffer better suggestions for your ?error.

[anniesboy]

Have got optimum start enabled ?

https://ensupport.getconnected.honeywellhome.com/s/article/How-do-I-enable-or-disable-Optimum-Start-or-Optimum-Stop-on-the-evohome-ATC928G2000?language=en_US

If not set the time come on earlier as the temperature had increased by 2.5c hence not an error but its taking time to heat up.

[haggis999]

My wife told me that the radiator in our bedroom was cold at 8:00am this morning. From memory, I think the Evohome app was still showing a target of 15 degrees. Even if the schedule had been followed correctly, the system would not have needed to rise by 6 degrees, as the ambient temperature was 17.5 degrees. I've now fitted an HR92 to the bedroom radiator, so it now has its own dedicated zone, as does our dining room with a couple of HR92s. With luck, all will be well tomorrow morning. Optimum start was already enabled.

I am still running all the other radiators in the house via my Living Room zone, using a single unattached HR92 (both this HR92 and the Evohome controller are in the living room). In the Zone Configuration menu I have a Temperature Sensor setting of 'EVOTOUCH SENSOR', while the Heating Type is 'RADIATOR VALVE'.

[haggis999]

We woke up to a warm bedroom this morning, so the new bedroom zone appears to have fixed the problem we had yesterday.

However, I am a little puzzled by the target temperatures shown on the controller or app. These temperatures do not always correspond with my set schedule. For example, at 11:20pm last night it showed all 3 zones with a target temp of 15 degrees. This was 10 to 30mins before any of those zones were scheduled to drop down to 15 degrees. Right now, it shows a target of 19 degrees for my living room zone, which is 5 mins before it's due to drop down to that level. What's going on here?

[MajorDanby]

Sounds like you have optimised start/stop enabled, I.e it will aim to be at that temperature by the set time. Personally I have optimised start enabled and optimised stop disabled

[haggis999]

Sounds like you have optimised start/stop enabled, I.e it will aim to be at that temperature by the set time. Personally I have optimised start enabled and optimised stop disabled

I have both Optimum Start and Optimum Stop enabled. It did occur to me that these settings might be modifying the displayed target settings but I failed to find any confirmation of that in the Evohome User Guide.

Incidentally, I noticed this morning that the Evohome controller was displaying the Euro currency symbol on one of my zones to indicate that Optimum Stop was in operation, but that symbol wasn't shown in the app display.

[haggis999]

Not only does the Honeywell Home app fail to show the Optimum Stop symbol (and probably also the Optimum Start symbol), it doesn't always show the same temperature readings as the Evohome controller.

Earlier this morning, the controller said that the current temperature of my dining room was 22 degrees, but the app display was 21.5 degrees. About 4 minutes later, the controller reading dropped to 21.5 degrees. It's not a big deal, but can anyone explain why the app and the controller temporarily drifted out of sync?