[OpenTRV-interest] Question from Steve R

Damon Hart-Davis dhd at exnet.com
Sun Nov 22 13:40:38 GMT 2015


The OpenTRV works from the valve outwards, ie an OpenTRV unit should be able to function stand-alone as a smart TRV that turns a rad off for you when you’re not around (and can have a couple of simple programs set).  The aim is to save 30% of the energy that that rad would otherwise use without loss of comfort.

If you add an OpenTRV boiler controller which simply listens to calls for heat from the OpenTRV valves instead of using a single house thermostat the aim is to get savings to 50%

The target price for a single OpenTRV valve, and no more should be needed to get started, is £10 retail.  A typical whole house target price including boiler control is £100—£150 and should save up to £300 per year from your gas bill (and the carbon that we care about).

You can buy a kit board from us (£25+VAT) and a third-party radio-controlled valve (£30-ish) to control a single rad, and another kit + relay to control the boiler.

For that all the software, hardware, protocols, etc, are open, so it’s relatively easy to make your own: it thinks it’s an Arduino.



> On 22 Nov 2015, at 13:25, Steve Rogerson <steve.otrv at yewtc.demon.co.uk> wrote:
> I think I must have got the wrong end of the stick wrt to what this list is
> about. I thought it was "open" "thermostatic radiator values". It seems to
> that Evohome - good though it looks - is not open - and the "programmable
> motorised trvs" (PMTRVs) that I've seen are not "open" either.
> I thought that this list was about creating an open programmable trv :-(
> I was hoping that there was (and I think I saw this in connection with
> opentrv) a  device that could replace the standard TRV with something that
> operated by a probably wireless signal that is generated by a control server
> based on temperature and time. I think I can create such a beast by getting
> and arduino and a servo to close and open the valve. Easy in principle though
> there are several issue to overcome.  One being the price with an Arduino and
> ethernet or wifi + a servo + sensor I'd be luckily to get much change out of
> £50. Also it would about the size of a cricket ball and at least initially be
> very fragile.
> I would ideally like a servo and arduino nano + small wifi like the ESP8266,
> say in a 3D printed case (I don't have a 3D printer - yet). Making it about
> the size of a typical TRV.
> ... and it shouldn't be beyond the wit of electronics engineer to design
> something a lot better, but that's where opentrv comes in - or at least that's
> what I thought.
> Steve
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