[OpenTRV-dev] V0.2-Arduino: getting started

[Damon Hart-Davis]

On 1 Apr 2013, at 11:10, Stuart Poulton wrote:

> I've been thinking about this, USB adds to the cost of a chip, yet allows for more configurability, I think I'm moving toward a model where USB and RF are used, so USB + Power for those TRV's where it's possible to cable, RF + Battery for those where cabling isn't possible.

Hi,

Note that any of the following may be reasonably wired or wired:

  * (P) Power (eg wired via USB phone charger, unwired with batteries)
  * (R) Radiator valve (direct drive via motor vs RF drive to allow for better placement of sensors and control)
  * (B) Call for heat from central boiler (wired a la Wookey's house, RF where we don't have data cabling flood-wired)

Where possible I'd like all units to be configurable (including setpoints, schedule and time) or reprogrammable via a local "USB" interface.

But for lower-cost end-user deployments of very simple warm/frost devices that can go on the valve (wired valve) and have local mains power (wired power) available then I agree that a simpler design may be possible.  I suspect that wired boiler will be a rarity except for (a) geeks' flood-wired houses and (b) the TRV node in a room with the boiler such as my kitchen.

We should maybe analyse the likely frequency of occurrence of the three wired/unwired combinations for our own possible deployments to get an idea of the combinations to support optimally?

I'll start:

3 x bedrooms: power close to rads, no data wiring, so can be wired for power and rad (ie physical unit on valve head) but not boiler: 3 x P/R/nB.
1 x living room: power close to rad, *could put wire through wall to kitchen but probably unpopular*, so P/R/nB (or at a pinch P/R/B).
1 x kitchen: power not close to rad and rad not close to boiler, so current power-hungry always-RX combined node is good candidate for wireless rad valve and is P/nR/B.

At least two of those bedroom TRVs would benefit a lot from being able to be locally configurable (ie not necessarily programmable) to have time and a schedule set, but a simple "learn" button on a 24h repeat (for 1h) might work fine.

I'll copy some of this into the 'Case Studies' wiki page.

Rgds

Damon