[OpenTRV-interest] Weather compensation

[Damon Hart-Davis]

Hi,

One variant of our hardware (for a district heating project) was measuring return temperatures (and flow was measured centrally), but in general a modern boiler should manage its flow and return itself, eg modulate down then shut down if the return is too high.

Rgds

Damon


> On 22 Dec 2016, at 17:10, Rob May <rob at themayfamily.me.uk> wrote:
> 
> > 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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