Wi-Fi controller

[paulockenden]

Anyone with the new controller, can you tell me whether yours feels warm to the touch, particularly top left?

I've noticed that mine does, but only when it seems to be doing battery management. e.g. if it has been off the stand for a while and is charging, or other times about once a day or so it seems to top up the battery (you can tell because the little icon appears top right).

My concern is that it's difficult to use the controller as a thermostat if it's doing this, but maybe it's just my unit?

P.

[HenGus]

My Evohome is wall-mounted. The left hand side plastic fascia is a tad warmer than the rest of the controller; then again, having checked it a second time, I might just be reacting to your suggestion.

As far as using it as a thermostat, I have not had any issues. I had some concerns when I was installing it as the zone temperature was showing 30C. I concluded that this was down to me handling the controller whilst setting up the rest of the system.

[DBMandrake]

I find I have to set a -1.0 degree calibration offset for the evotouch's built in temperature sensor to get it to agree with other digital thermostats I have around the house. I have always put this down to the heat generation inside the unit, which I imagine would be a lot greater than that in something like a DTS92, since there is a higher power CPU and an always on backlight etc...

In testing this I am not just believing the displayed temperature figure, because we all know that it is biased towards the set point and then rounded to the nearest 0.5 degrees on top of that, making a direct comparison of readings error prone.

Instead I set the set point to a particular temperature for at least 2 hours in a closed room that is left alone (doors/windows left closed for the duration) for it to reach an equilibrium - with the other thermostats located right beside the evotouch, so they are measuring the same part of the room and themselves have had time to reach their own equilibrium.

As long as the heat generation in the unit is constant, the offset error will also be constant and can thus be calibrated out with the calibration setting. (Unlike the calibration setting on an HR92 that can only compensate for a hot radiator, and is then wrong when the radiator is cold)

As for a reading of over 30 degrees when handling the controller - I have also seen this. Even just 5-10 minutes of constantly holding and handling the device during a long programming session for example is enough for the reading to go over 30 degrees - not surprising when normal skin temperature is about 33 degrees.

The sensor in the evotouch is very fast responding so it only takes a few minutes for the reading to go sky high when handling it.

[paulockenden]

If the offset was constant it would be easy to 'dial out'. It's the fact that it varies - depending on whether it's charging the batteries (or keeping them topped up) what I really noticed. I can even see the little blips on my temperature graphs.

[Mavis]

My Evohome is wall-mounted. The left hand side plastic fascia is a tad warmer than the rest of the controller; then again, having checked it a second time, I might just be reacting to your suggestion.

As far as using it as a thermostat, I have not had any issues. I had some concerns when I was installing it as the zone temperature was showing 30C. I concluded that this was down to me handling the controller whilst setting up the rest of the system.

I'm with Hengus. This afternoon I have just 'reset' the batteries so the controller is charging at the moment. I think that the left side may be a tiny bit warmer but not sure if it is in the mind (mine is on the desk stand).

[DBMandrake]

If the offset was constant it would be easy to 'dial out'. It's the fact that it varies - depending on whether it's charging the batteries (or keeping them topped up) what I really noticed. I can even see the little blips on my temperature graphs.

I keep mine on the wall mount all the time except during occasional binding or reprogramming, so I probably wouldn't notice any recharging I suppose.

Depends what you mean by "blips" - I don't see any blips on my graphs that would correspond to battery charging, however I do notice that using the evotouch internal sensor results in a lot of +/- 0.5 degree "hunting", where a temperature that is half way between two 0.5 degree increments tends to randomly toggle back and forth between the two figures on the display as often as every 30 seconds or so. (And this does show up in the graph too)

On the other hand remote sensors don't exhibit this behaviour - probably because they only broadcast their temperature reading once every 4 minutes. Are you sure its not just this random toggling effect that you're seeing on your graph ?

[paulockenden]

Absolutely sure. I'm using an HGI80 so I see temps with 0.1 degree resolution, not rounded to 0.5 degrees like you get with the API.

Look at this chart:chart (3).jpg

There's a blip at around 3am (no heating on and no heat sources active). But there's the same thing happening approx every six hours.

P.

[DBMandrake]

Interesting. I can't tell from your graph due to the compressed scales - how many degrees does the reading rise during this "charging" period, and how long does it last ? I've reassigned the internal sensor to the hallway where the controller resides, and the hallway is completely off over night so I'll look for any bumps in my graph tomorrow. (I only have 0.5 degree resolution of course, so may not see anything...)

[paulockenden]

Probably 1 - 1.5 degrees. And for about half an hour then it tails off.

[DBMandrake]

No sign of any suspicious temperature rise overnight here, at least via the API...



Do you also see a bump if you query via the API ? Do you leave the controller on its base most of the time as I do or is it frequently removed ?

By the way I use the wall plate but remotely mount the transformer in another room in the wiring centre.

[paulockenden]

I don't think the API has the resolution to notice the bump.

Remember, once the temps have been 'processed' by Evohome they only have 0.5 degree increments then on top of that they are always rounded towards the setpoint, so the temp can be out by a degree. The HGI80 picks up the temps before they've been mangled like this. Strangely, even temps from the controller itself!

P.

[DBMandrake]

I don't agree - if there was really a 1 to 1.5 degree change it would still show via the API. Remember that during the test period the set point is fixed at 5 degrees so the "bias" is always in one direction. This leaves only the 0.5 degree resolution, so I'm sure that a 1 or 1.5 degree change would show.

Do we know whether the measurement is rounded to 0.5 degrees first and then biased, or is it biased first and then rounded ? We don't really know, however from what I've observed it appears to be biased first, (perhaps by a scaling factor) and then rounded. I base this on the fact that changing set points from below to above the current measured temperature doesn't always change the reading by 0.5 degrees, which it would if biasing was done after rounding.

Do you use the wall mount with the transformer located behind the wall mount by any chance ? Are you sure it's not heat from the transformer ? As I say, although I use the wall mount the transformer is mounted elsewhere with the wall mount plate screwed directly onto a wall papered plaster surface, so the only heat generation is inside the device itself.

If you use the wall mount with the transformer mounted behind it, do you still see the same issue if you mount the controller on the table stand, which does not have the transformer immediately behind the controller ?

[paulockenden]

Do we know whether the measurement is rounded to 0.5 degrees first and then biased, or is it biased first and then rounded ?

Someone from Honeywell posted here that it was the latter. But it's one of those parts of the system that's shrouded in mystery!

Do you use the wall mount with the transformer located behind the wall mount by any chance ?

Nope. Table stand, on the corner of a desk, and away from all heat sources. The additional warmth when topping up the batteries comes from the controller itself, not the transformer, which is a long way away.

I'm going to have to take a photo with my thermal imaging camera before I'll convince you, aren't I ?

[DBMandrake]

You don't need to convince me - I'm sure you are seeing this issue as the HCI80 graphs are proof enough.

However I don't seem to be seeing the same issue so I'm just trying to work out why. Another thing that occurs to me is maybe there is a problem with your batteries, which is causing the unit to repeatedly try to recharge them ? Maybe once my batteries reach full charge it drops to a trickle charge and stays there, but yours maybe periodically does a faster charge ?

Have you checked the spring contact for the batteries for corrosion ? After reading about this in another thread I was surprised to find that mine was black with corrosion, which I cleaned up a couple of days ago...