[OpenTRV-interest] First impressions and questions

[Damon Hart-Davis]

> On 25 Jan 2017, at 20:17, Simon Hobson <linux at thehobsons.co.uk> wrote:
> 
> Sounds simple enough :-)
> Comes back to 2-way communications again, and the security & battery life issues that go with it.
> 
> I do recall there's been a small amount of discussion about that here in the past - might be worth searching the archives and see what's been said before.
> 
> 
> I have a question for you on how the unit is performing.
> I assume you have the one unit, and it's not currently connected to a boiler controller. Is it doing "sensible" things when there's a call for heating in the room, but the boiler isn't running ? I can't help wondering if it might be winding the valve fully open, saturating any integral term in the control algorithm, and perhaps then overheating the room when the boiler does fire up (due to timer & room stat calling for heat).
> There's also issues with combi boilers (spit) which go off (as far as the heating is concerned) while people are having showers so even with a full Radbot system and boiler interface, there'll still be "demand but no heat supply" situations.


To overcome a new and exciting pathological case that I noticed a few months ago (a valve opens just enough to warm itself and be convinced that the room is toasty, but is not actually providing any significant heat at all) I re-wrote the algorithm to open fully then close more cautiously to reduce noise and battery drain; this is apparently fairly common practice.

You can sample the two algorithms at the head of the TRV1.5-RC3 and TRV1.5-RC4 production branches, to see which you prefer.

All variants of the algorithm cope with calling for heat but getting no response.

Rgds

Damon