DamonHD

For us the Thermino was able to fit under the then extant combi, but hold ~2 days' heat. https://www.earth.org.uk/note-on-solar-DHW-for-16WW-UniQ-and-PV-diversion.html#2022-03-09

FWIW I use microzoning to mean control per room or per emitter (eg radiator).

I'd quite like a small lump to sit on top of my Thermino, maybe to instill a sense of mortality in it! B^>

No and no.

Avoiding getting the batteries out of balance is important, and what @ProDave suggests seems like a decent temporary workaround.

I do not think that 'everything open' is always right (formal paper https://www.mdpi.com/2071-1050/16/11/4710 - TL;DR https://www.earth.org.uk/To-Zone-Or-Not-To-Zone-with-TRVs-for-Retrofit-Heat-Pumps.html - discussion on the Heat Geek thread here), but definitely go for weather compensation: you do not need to run at anything near the maximum temperature most of the time and so WC will improve CoP and reduce cycling.

There are standard calcs I suspect, likely in part dependent on 99% percentile windspeeds in your area.

To add: being the H&S governor too, I did ask for additional steel fixings / ropes to the edge of roof surfaces to further reduce the risk of takeoff or at least stuff sliding on to kids below, but I don't think there was any evidence of anything shifting in even quite high winds. The panels were initially on frames with ballast weights. I think that on the new roof trays may have been used in part, but it is the ballast that is doing most of the ... uh ... heavy work... as suggested above, AFAIK.

16kWp on a school roof many years ago - all fine. Largely survived building works and some being shuffled to an entirely new roof also. https://www.earth.org.uk/solar-powered-schools.html

See live-ish charts of TRV open %-age further up the thread. To avoid various problems they open fairly fast but close as slowly as they can without temperature overshooting too far. They do not close fully if temperature does not significantly overshoot.

I have been out all day so I may not get to respond to everything... OpenTRV / Radbot are intended to just this where possible by bringing rooms up to temperature when occupancy is predicted. And indeed my bedroom Radbot did so this morning. Some of the other things that you mention are things that I have considered since handing over the Radbot IPR and there is space in my research plan to think about and maybe model or prototype some of them.

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But plain WC does not increase flow temperature in response to anything other than falling outside temperatures. If you are saying that someone might shift the whole WC curve up then that is a different matter which I address as "fiddling with the settings". Notionally that WC curve is *computed* from the heat loss calcs at installation time and left alone. 😀

@JamesPa I hear what you say and I shall think about it: thank you for tussling with this. But where you say "I think the latter results prove that the saving in the former is really attributable to the reduced temperature of the inhabited rooms, not to the setback in the uninhabited ones!" taken literally and simplistically is untrue: it is a simple matter of physics that all internal spaces that are at a lower temperature than they otherwise would be lose heat to outside more slowly than they otherwise would, and thus reduce heat demand, and where WC is in use that reduces electricity demand and thus cost. Note that the initial HG claim being countered was that reduced heat demand could cause increased electricity demand, which is again simply not true with use of plain open loop WC. Whether that arrangement is acceptable for other reasons, some of which we have discussed in this thread, is a separate issue.

FWIW my own live-ish TRV percentage-open chart (for most of the rads): and call for space heat: Note that there is currently a problem with this system and it hasn't been fully commissioned (or paid for!) yet, and I am continuing to tweak as householder and researcher. So have a good laugh! B^>

I agree, which is why I'm doing my research, to see if there are any wheels that I can find to grease...

"Eating your own dogfood" is a standard term in the start up world and beyond, meaning that you actually use (and understand and stand by) your own product, which is IMHO the right thing to do. Far from petulant. I estimate ~100M rads in UK homes, ~1B in European homes, and about the same again in commercial properties. There are ways of misusing all tools. Most UK home heating systems are vastly oversized and fairly poorly installed and understood and used I believe. The minimum power output of my gas combi was more than double the maximum heating demand on the coldest days, so it spent all its time cycling regardless of TRVs. And the expansion vessel failure rate was only beaten by the diverter valve. My new heat pump seems somewhat better matched to heat demand, though was the smallest one that Octopus could do AFAIK.

AND if you are running open loop weather compensation yes. But I also point out that a small degree of feedback and loop closing may retain the electricity savings that you'd expect from the heat savings, and mitigate sag somewhat - I did not attempt to calculate how much.

I say in the paper that I spent a decade inventing a smart TRV (and bringing a commercial version to market). There are now ~500k Radbots out there. I have views on TRVs, and I am eating my own dogfood at home, but I have no commerical involvement with Radbot any more. AND I am hoping during my PhD to fill some (huge) gaps in the academic literature about TRVs and in particular interactions with heat pumps, and some of that research may be funded by manufacturers because everyone would really like to know! My aim and thesis working title is "Improving UK home heating decarbonisation". I suspect that that will involve TRVs for reasons that I have laboured in this thread and elsewhere, but if TRVs aren't part of the answer then no problem. I shall find out what else is. My PhD research plans: https://www.earth.org.uk/img/research/20240917-PhD-confirmation/confirmation.pdf

I calculate the grid CO2 intensity and log it here: https://www.earth.org.uk/data/FUELINST/log/live/ and then combine it with exports/imports for each hour to compute the total. See the end of the page.

Yearly CO2 calcs for electricity and gas, about +225kgCO2 for the year. I now hope to see this drift back to slightly negative as the grid gets greener, etc. https://www.earth.org.uk/saving-electricity-2024.html

Just finished my yearly CO2 calcs for electricity and gas, about +225kgCO2 for the year. I now hope to see this drift back to slightly negative as the grid gets greener, etc. https://www.earth.org.uk/saving-electricity-2024.html

1) The static calcs I did in the model in my paper suggested very significant energy savings by doing TRVs right, which back up my experience. 2) Dynamic response to occupancy is another significant saving, eg heating unoccupied bedrooms during the day even if people are home all day. Again, reinforces what I saw in substantial trials. 3) Given how cheap and easy to use TRVs are (~1% of the rest of the heating system ish) and can save 10--30% of consumption and footprint for <2Y financial payback, never mind comfort, why NOT put them in by default, even if you leave them a bit high if in doubt and lean on WC as much as possible?

Because one curve for the whole home is clearly insufficient at some level when the heat losses and gains of rooms relative to one another is changing.

Whoops, I borked that image by moving it and I can't edit my post. Here's a newer and betterer one for the whole of December: