[OpenTRV-dev] Update and Reading Frequency

[Kevin Wood]

I'm inclined to agree. Look at the thermal inertia of the room and the
radiator that heats it. Open the TRV and I'd bet it takes 30s before you
have any useful heat output from the radiator. It's probably several
minutes before it reaches full output. Moreso if the boiler has had to
fire up in response.

Ditto the room temperature. Aside from events like a window or door being
opened, which we can't do much about, there will be massive thermal
inertia which works in our favour. I'd also say a couple of minutes would
probably work fine.

Look at a conventional mechanical TRV and imagine how sluggishly it
responds, yet I find they keep a room perfectly comfortable. My wife
seemingly isn't happy unless the temperature is steadily rising, though 
<sigh!>. ;-)

Kevin


> It depends on the cost of powering up, initialising the temp sensor, etc.,
> but I think 30s may be too frequent most of the time. If the temp is
> 'much' too low or high then it could probably be on the order of 2-3mins:
> it's not going to change that quickly. Similarly, when you're at steady
> state. When heating to reach a temperature 30s samples\transmissions might
> be appropriate to avoid a huge overshoot, I'm not sure. I'd say we should
> sample before the temperature could reasonably be expected to change by
> more than 0.5 or 0.25 degrees.
>
> I'm a fan of a fixed, powered, always-listening central hub: in that case
> you can transmit updates at 'random' intervals (whenever the temp changes
> 'enough'). The thermostat could choose not to power up the wireless and
> send an update every time it takes a measurement.
>
>
>
>
>
>
>>________________________________
>> From: Stuart Poulton <EMAIL ADDRESS HIDDEN>
>>To: Closed list for developer discussions
>> <EMAIL ADDRESS HIDDEN>
>>Sent: Wednesday, 10 April 2013, 7:12
>>Subject: [OpenTRV-dev] Update and Reading Frequency
>>
>>Hi All,
>>
>>I'd be interested on people thoughts, obviously with battery powered
>> wireless devices tranmissions need to be kept to a minimum. What do
>> people think about sampling frequency from wireless temperature sensors,
>> and similarly how frequently should a TRV head request updates ?
>>
>>I'm currently thinking about ~30 seconds for each.
>>
>>Stuart
>>_______________________________________________
>>OpenTRV-dev mailing list
>>EMAIL ADDRESS HIDDEN
>>http://lists.opentrv.org.uk/listinfo/opentrv-dev
>>
>>
>>_______________________________________________
> OpenTRV-dev mailing list
> EMAIL ADDRESS HIDDEN
> http://lists.opentrv.org.uk/listinfo/opentrv-dev
>