Evohome - poor temperature regulation

[erik]

Greyhound, the reason they're testing it under low load, is that if there's high load (for example -5 outside and +20 inside and poor isolation), that 1 minute of heat per 10 minutes will probably not raise temperature in the room. In that case, you won't notice the problem. It will seem like it's keeping temperature perfectly.

There's logic behind requesting heat even when 0.1 above setpoint. It prevents drops below the setpoint. But there's no logic anymore when it keeps getting warmer and warmer in the course of a few hours and it then still requesting heat 1.0 above setpoint.

Rameses: the problem occuris with ANY temperature sensor. HR80, HR92, Evohome and Round, located at GOOD spots. Also on the same spot as the old thermostat which does fine. Also, my own thermometers tell me the same thing (except that Evohome of course is always lie'ing a bit about the measured temperature, making it seem closer to setpoint than it is).

G4RHL, Evohome overshoots even further if you use it in thermostat-modus (no radiator valves involved), so it's more noticable in that case. Also, Evohome lies a bit about measured temperature. If it says 21.5 during setpoint 21, it might very well actually be 21.9. Have you confirmed with your own thermometers that it 'only' goes up and down 0.5? I expect it to be around 0.7-0.8 when using radiator valves.

[greyhound1234]

Where are you taking your temp readings from?

And you mentioned in a previous post you are using the internal sensor on the controller, is this correct still?

When I put the rad zone valves on, I set all zones to use remote device temperature sensor, not evohome controller sensor.

[greyhound1234]

Ignoring arguments over how the TPI algorithms should behave, the behaviour of other zones is clearly not correct. Can anyone else replicate this?
e.g. Zone A and B both previously set to 17.0 and both holding 17.0. Zone A is then set to e.g. 20. Zone A will heat up. Zone B will heat up. Zone B will only stop heating up at 18.5 (1.5 degrees above it's setpoint, the zone valve closes off).

[greyhound1234]

Perhaps we should have a poll of what firmware we have, and whether we are happy with it.
v25 16Jan2014, and not happy...
Rameses - humour me, please tell me what firmware version the Evohome controller units are currently leaving your factory with, right now.

[orange]

Perhaps we should have a poll of what firmware we have, and whether we are happy with it.
v25 16Jan2014, and not happy...
Rameses - humour me, please tell me what firmware version the Evohome controller units are currently leaving your factory with, right now.

there is only that initial release firmware - AFAIK - as of today no further updates are planned to existing units - bugs or not.

[HenGus]

there is only that initial release firmware - AFAIK - as of today no further updates are planned to existing units - bugs or not.

A very short-sighted marketing approach IMHO. Even the God 'Apple' supports its older technology with firmware updates until such time as the hardware becomes the limiting factor. My 6 year old MacBook is currently running Yosemite OS X - albeit, slowly!

[erik]

Honeywell thinks their software does not have critical mistakes in it, so they don't release updates. New units also have the same firmware. So far.

greyhound, you are correct. The radiator valve in zone B in your example should close much earlier. Letting it go 1.5 over setpoint is way too much.

[roydonaldson]

Nest automatically updates their firmware for their customers, adding new features and functionality and enhancing their customers investment in their platform. The industry has changed from dedicated hardware devices to a combination of solid hardware enhances by agile software delivery.

[Rameses]

Ignoring arguments over how the TPI algorithms should behave, the behaviour of other zones is clearly not correct. Can anyone else replicate this?
e.g. Zone A and B both previously set to 17.0 and both holding 17.0. Zone A is then set to e.g. 20. Zone A will heat up. Zone B will heat up. Zone B will only stop heating up at 18.5 (1.5 degrees above it's setpoint, the zone valve closes off).

greyhound1234 - Firstly - when you say zone valve - do you mean Hr92 on the radiator? If so then how do you know this is open?

There is no way the Hr92 will call for heat unless your at set point (and been falling) or below) - it will then 'trickle' the water in to attempt to control the temp of the rad (at 17 degree) - are you saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? Or are you just looking at the room temp?

Is Zone A linked to Zone B? (next door? linking room? etc)

[Rameses]

There are no firmware changes to the controller.

There are and have been firmware changes to the gateway - which provide enhancements, such as schedule editing etc - future enhancements are road mapped.