[OpenTRV-interest] Programmable TRV performance

[Damon Hart-Davis]

Hi,

Note of course that you may have temperature gradients across the room: in one of mine I observe ~2C for example.

So have the sensor near you if possible if this is an issue for you!

Rgds

Damon


> On 16 Feb 2015, at 16:06, Mark Wigmore <EMAIL ADDRESS HIDDEN> wrote:
> 
> Thanks Damon, I was thinking it might be a combination of factors as you suggest.
> 
> Looks like the best thing would be to have a TRV controlled by a wireless sensor in another part of the room.
> 
> Cheers,
> 
> Mark
> 
> On 16 February 2015 at 15:49, Damon Hart-Davis <EMAIL ADDRESS HIDDEN> wrote:
> Hi,
> 
> It may start closing well before the target temperature to try to minimise fluctuations; I start closing about 1C below the target I have in the OpenTRV control loop.
> 
> Also it may see some direct radiative heating as I sometimes do on OpenTRV units, and be reacting to that.  It’s still something I’m working on handling fully elegantly.
> 
> There may also be a calibration error of +/- 1C on the temeprature sensor (the one we use are closer than that).
> 
> In other words, that place may be approaching 20C including direct radiative heat and air rising from the flow/return pipe when the valve closes thinking that it’s hit 21C.
> 
> Rgds
> 
> Damon
> 
> > On 16 Feb 2015, at 14:52, Mark Wigmore <EMAIL ADDRESS HIDDEN> wrote:
> >
> > Hi,
> >
> > Sorry if this is a bit OT, but I thought people in this forum might be the most likely to know the answer.
> >
> > I have a Honeywell HR25 programmable thermostat on my bedroom radiator. It is programmed for 21degC in the mornings, but I can hear the valve start closing from about 17.5deg as the room warms up and completely closed by 19deg room temperature. There's a good airgap all round the TRV; 500mm to the bed, 300mm gap under the bed, and 600mm at the end of the bed nearest the TRV. There is a window 240mm above the rad and the curtain stops 170 above.
> >
> > Any idea what's going on?
> >
> > Regards,
> >
> > Mark
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