Is EvoHome controller a thermostat?

[MrBoy]

I'd never thought of this but something I read online suggested my EvoHome touch screen controller could also be used as a zone thermostat, is this the case as it would save the cost of one additional thermostat?

[Dan_Robinson]

Yes it can.

[HenGus]

I'd never thought of this but something I read online suggested my EvoHome touch screen controller could also be used as a zone thermostat, is this the case as it would save the cost of one additional thermostat?

With the caveat that it is best placed and left on a wall mount. Handling the unit can lead to an erroneous zone temperature. I have a 3 HR92 zone in my hallway that the controller manages most effectively.

[filbert]

I was originally going to save the cost of wall stat for a zone with a radiator with a cover (so the HR92 might not work properly) but I thought that the downside of having to avoid moving it into a different room when using it to adjust system, etc, settings outweighed the saving in cost.

In the event, I actually put the controller under the stairs, away from the relevant zone anyway. The cost saving is small compered to the total cost of the work that I was having done - and the greater flexibility seemed worth the extra.

[Ian_W]

Something else to watch out for is that when the controller decides to charge its batteries, its measured temperature can increase by a few degrees C for several hours. This has caught me out when using the controller as the room's temperature sensor. Maybe there is a way to convince it to charge the batteries at a given time when this mis-reading won't be a problem, but I haven't found it yet.

[MrBoy]

I've spent a few minutes trying to figure this out, or Google a quick answer, and am not sure if I've succeeded or not.

In configuration, I've give into zone config and the only thing I can find is "temperature sensor" which has two options Evotouch Sensor or Remote Sensor (default). Given that Evotouch seems to be an entirely different product range, is this correct? I'm not sure how else to bind the controller to a zone.

As an aside is there a way to see what temp the controller thermostat is measuring directly? I'd like to compare the HR92 temp to the controller temp.

Thanks

[Dan_Robinson]

Evotouch is the dirty great big screen you're holding in your hands. The clue is in the name.

Evohome is the suite of products.

[MrBoy]

According to Google evotouch is also a precursor to EvoHome, I keep getting manuals for that when I search.

Anyway did this meant I did it right... Simply set the temperature sensor setting for my zone as Evotouch instead of remote? I tried this but saw no change in reported temp to confirm or deny I'd got it right.

[Dan_Robinson]

Hey man, I've only been selling this stuff for a decade. What do I know

[MrBoy]

Given that Honeywell don't advertise the product as Evotouch as far as I've seen is it possible that name has just stuck in the trade from an earlier iteration as a generic term like Hoover?
My guess is they called it Evotouch in the days when a touch screen was something special then rebranded, but the name lives on in hidden settings and the memories of those who were there at the beginning

[MrBoy]

It's actually be kind of interesting (for a nerd like me) to read the evolution of the current system from whenever it first appeared

[Ian_W]

Anyway did this meant I did it right... Simply set the temperature sensor setting for my zone as Evotouch instead of remote? I tried this but saw no change in reported temp to confirm or deny I'd got it right.

Yes, that's right. You should see the reported temp for the zone change on the Evotouch screen shortly after you change the setting (that is, within 30 seconds or so) - assuming the Evotouch controller is actually measuring a different temperature to the HR92, of course.

[DBMandrake]

Something else to watch out for is that when the controller decides to charge its batteries, its measured temperature can increase by a few degrees C for several hours. This has caught me out when using the controller as the room's temperature sensor. Maybe there is a way to convince it to charge the batteries at a given time when this mis-reading won't be a problem, but I haven't found it yet.

Funny, I graph all my zones and use the controller as the sensor for my hall zone (controller wall mounted) and I have never seen a noticeable temperature rise when the controller is charging its batteries on my graph, certainly not "a few degrees C for several hours". Maybe half a degree at most if that. I wonder what is different with your setup ?

I do find I have to set the calibration to -1.0C to match an independent thermostat - but that offset required seems to be very constant and is probably due to overall heat production from the device independent of any battery charging.

[Ian_W]

Funny, I graph all my zones and use the controller as the sensor for my hall zone (controller wall mounted) and I have never seen a noticeable temperature rise when the controller is charging its batteries on my graph, certainly not "a few degrees C for several hours". Maybe half a degree at most if that. I wonder what is different with your setup ?

Bearing in mind I installed my system only about three weeks ago and I've seen this behaviour once, it's possibly a one-off and perhaps I shouldn't have generalised so quickly. However I did see the reported temp go up by 2 - 3 C correlating with the battery charge indicator showing on the top right-hand corner of the controller display, and this took at least overnight to sort itself out. My set-up differs from yours insofar as the controller is on the shelf mount/cradle, but very rarely leaves it.

ETA: there's an earlier reference to this behaviour in this post by @paulockenden.

I do find I have to set the calibration to -1.0C to match an independent thermostat - but that offset required seems to be very constant and is probably due to overall heat production from the device independent of any battery charging.

Mine seems to be spot on, zero offset in steady state, compared to a known-good thermometer - provided I leave it alone and don't handle it. It seems very sensitive to hand heat, or perhaps I'm just holding it wrong (to quote a phrase...).

[HenGus]

My set-up differs from yours insofar as the controller is on the shelf mount/cradle, but very rarely leaves it.

In my experience, any handling of the controller will cause an issue when the controller is operating in a temperature sensing mode. Most people tend to hold the controller in their left hand which blocks the vents on the side.