[OpenTRV-interest] Weather compensation

[Rob May]

> though I think the efficiency and therefore CO2-saving gains are mainly
> from reducing flow and return temperatures during milder weather.

Have we considered a way to add sensors to measure the flow and return
temperatures? (even if we can't control them).  I may be mis-remembering,
and may be showing my lack of knowledge, but I'm sure that I read somewhere
that many condensing installations were not efficient as the return flow
was always too high for them to actually do the condensing bit.



On 22 December 2016 at 13:43, John <john at stumbles.org.uk> wrote:

> Hi Damon
>
> On 22/12/16 12:57, Damon Hart-Davis wrote:
>
> I have always assumed that weather compensation is simply the part
>> that adjusts settings (eg flow temperature) based on current external
>> temperature, ie reactively.
>>
>
> Yes, that's what the boiler schemes I've fitted do. Worcester's Wave also
> senses internal temperature at the controller (as per regular programmable
> thermostats) which I think they describe as "influence" but I don't know
> exactly how they combine the factors.
>
> There are opportunities to do more than that with the forecast,
>> getting heat into the house early/late/whatevs if the next little
>> while is going to be especially hot/cold/windy depending on the
>> thermal time constant of your house.  Potentially especially good for
>> those with (say) UFH for example.
>>
>
> There's possibly some scope for some smart tweaking there, though I think
> the efficiency and therefore CO2-saving gains are mainly from reducing flow
> and return temperatures during milder weather.
>
> Note that the compulsory compensation suggestion is out for
>> government consultation right now, and I voted against it given the
>> long payback times and the other rather lower hanging fruit (ie
>> better places to spend the money to save energy first), and even
>> against compulsory timers since most people don’t use them:
>>
>
> Why do you think weather comp would have a long payback time? Even at the
> price manufacturers charge for their thermistor-in-a-box sensors and the
> labour required to fit them the total cost should be in the £100-£200 range
> which should give a payback well within the lifetime of the kit.
>
> In my experience as a heating installer most people do use some form of
> time control on their systems, even if a significant minority don't. I
> think the Regs could do a service by assessing and mandating a usability
> factor for controls: there are some that even I struggle to set (looking at
> you Drayton!). But even if some people don't use their timers the building
> regs are there to mandate what installers provide: if time control isn't
> compulsory then cheapskate installers won't fit them and even householders
> who want and would use them won't have them. And given that a timer costs
> the square root of sfa there seems no justification for omitting them.
>
> https://beisgovuk.citizenspace.com/heat/heat-in-buildings-
>> online-consultation/consultation/
>>
>>  Guess what I thought *would* be a good solution that policy should
>> support?  B^>
>>
>
> Intelligent TRVs? That would mean mandating Honeywell and a few other
> mfr's currently very expensive (and in some cases rather flakey) kit, which
> would surely have an unviably long payback time?
>
> --
> John Stumbles                                    http://stumbles.org.uk
> :-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:
>
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