[OpenTRV-interest] Integrating some OpenTRV hardware into an unusual heating system

[Mark Hill]

Hi Tim

I would have thought that it should be quite possible to hack (with a
hacksaw?) the plastics of the controller down to size. As they are not
going to be visible in your house, that should be fine.

Again, specifically for your case, I'd think about powering them off mains,
as they will not be visible generally. That means running wires and
modifying the cases to accomodate this.

Lastly, I'm keen to follow up on your comments from Saturday about the
rotating top dial of the OpenTRV case being not a necessary part of the UX
and exploring alternatives. Won't make it into the mix for this January's
version, but it is something I'd like to do long term. How many
UX/industrial designers do we collectively know? Probably worth me
organising a brainstorm/workshop session for interested parties next year.

Regards, Mark

On 2 December 2014 at 20:27, Tim Small <EMAIL ADDRESS HIDDEN> wrote:

> Hi,
>
> Thought I'd post here by way of writing up some of what I said at OpenTRV
> Conf at the weekend, as well as some subsequent thoughts.
>
> I'm planning on implementing a heating control system which is largely
> FOSS based for my house (the heating for which is currently under manual
> control only), as an alternative to buying some overpriced commercial
> system which probably won't work very well with it.
>
> I use a single gas-fuelled combi boiler to heat a mixture of under floor
> heating zones (7 UFH zones spread across 4 rooms), and radiators (3 located
> in 3 rooms).
>
> There is no 'buffer tank', and all zones receive water directly from the
> boiler (i.e. without any of the standard UFH mix-down valve and pump
> stuff), since the rads are sized to work at the UFH circulation
> temperature, and the house is pretty-well insulated (1920s semi, which will
> probably fall just short of compliance with the Passivhaus "Enerphit"
> retrofit spec when I've finished putting EWI on, and fixed a few more
> things) - otherwise this scheme would often result in monster
> triple-convector rads.
>
> Individual UFH zones and also the radiators have their circulation water
> controlled centrally using UFH manifolds (which look like this -
> http://goo.gl/J5OZIM - the blue knobs are manual valves which un-screw to
> reveal the same M30.5 mounted pin-actuator valves that are commonly found
> when you remove the heads from radiator TRVs).
>
> This scheme is reasonably cost-effective to implement, but would benefit
> from some more-intelligent-than-usual control systems to minimise boiler
> cycling and achieve effective temperature control (i.e. without under/over
> heating).
>
>
> The features which I would like to implement in rough order of priority
> are:
>
> . UFH manifold flow control preferably using motorized valves - 10 in all
> in two locations.
>
> . A minimally functional (preferably Android-accessible) user interface
>
> . To incorporate the temperature readings from the in-floor 1-wire temp
> sensors into the control algorithms
>
> . On-off central heating control via relay
>
> . A half-decent Android-accessible interface
>
> . More extensive boiler control via Vaillant eBus interface (to replace
> on/off control) e.g flow-return temp monitoring and zone co-ordination to
> minimise boiler cycling
>
> . Optimum-on
>
> . Weather compensation and load compensation
>
> . Summer cooling via window actuators or other means (e.g. ground loop,
> summer-mode MVHR etc.)
>
> . Indoor air quality control (humidity and maybe CO2)
>
>
> My pre-OpenTRV plan was to use this GPL java code:
>
> http://sourceforge.net/p/diy-zoning/code/HEAD/tree/trunk/ (dz3-master /
> dz3-shell ) - which already does PID control, zone coordination, some sort
> of Android UI, and 1-wire temp sensor reading/logging.
>
> ... and integrate it into some hacked Honeywell HR20 actuators (for the
> rad circuits), and thermoelectric ones (for the UFH circuits).  I would
> prefer all motorized actuators (faster response), but the HR20s are too fat
> for this (can't fit two side-by-side on my manifolds).
>
>
> Now that I know that OpenTRV is about, I'd quite like to:
>
> 1. Possibly use some of the OpenTRV remotes (although I already have a
> load of cat5 in-place, so I could just use remote SHT temp/humidity sensors
> instead).
>
> 2. Use something based on the OpenTRV actuators if not too much of a
> headache - the current prototype OpenTRV valves are sadly also slightly too
> wide to fit on every port of my manifolds (50mm centres vs. ~55mm centres
> on the prototype), so if OpenTRV kit is to be used, some sort of case
> hacking or building will be needed.
>
> 3. Use OpenTRV boiler control.
>
>
> I'd probably still like to use the  DZ3 codebase (at least initially -
> assuming it works out - I last looked at the code when I had it controlling
> a single zone in my last home about 10 years ago) - but this may well
> fit-in with your plans for a centralised control mode for OpenTRV (since a
> lot of the things on my wish list are also on OpenTRV's lists).
>
>
> BTW, Thanks for the beer and pizza at the weekend guys!
>
> Cheers,
>
> Tim.
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