DamonHD

One swerve I helped with was to get solar PV for a listed property, within the curtilage for FiTs but outside the historic curtilage for listing purposes! https://www.earth.org.uk/installing-solar-PV-for-electricity-at-home.html#farm So there may be subtle things like that that help...

I am running WC, volumiser and bypass, with each (micro)zone able to call for heat, and no zones permanently on. Works efficiently and pleasantly for us, and typical cycles are an hour or (much) more. https://www.earth.org.uk/heat-pump-16WW-control.html

Filled up (as did all other energy storage) today for the first time this year... It's been a sunny March round these parts...

Water hammer, when the washing machine starts and/or stops drawing water?

You may find that diverting more slowly will let the tank absorb more heat before the thermostat cuts out by letting heat dissipate better in the tank. I have a grid limit of 8A/2kW set for my Eddi (immersion and heat battery downstream).

I am using a Thermino *alongside* my heat pump DHW tank, and I don't expect to be paying to import much electricity between now and September to make DHW... https://www.earth.org.uk/reconnecting-the-16WW-heat-battery.html

I absolutely agree about getting condensing boilers to actually condense. Anyone who wants to take up my rad stickers idea (now that DESNZ and Ogfem might be a little more receptive than when shown last time, under the previous government) and run with it is very welcome - I simply do not seem to have time. https://www.earth.org.uk/OperationTuneup/ ~GBP1 per household raw cost, everything done by the householders, I have 2nd/3rd round prototypes sitting on my desk still.

I prefer the "understanding first" approach suggested by UCL: https://journal-buildingscities.org/articles/10.5334/bc.388 Often putting a heat pump after simple cheap no-regrets fabric improvements will save more carbon. Quote: "The extent of fabric improvement needed will therefore vary across the stock. In some cases, e.g. where apartments are dominant, the role of fabric improvement may be limited. A recent detailed evaluation of a stock of 33,300 homes (85% flats) in London suggested that fabric measures alone would only achieve a 13% cut in gas use, at a cost of GBP31,900 per dwelling ..." Quote: "The largest additional upstream costs are likely to be in zero-carbon generation to accommodate the peak demand of a widespread shift to heat pumps. In addition, electricity networks in some places will need to be strengthened." Quote: "Residential buildings are homes: they need to be healthy, comfortable and affordable. ... that points to a high short-term focus on fabric improvement for households on low incomes and in poor housing." Quote: "... a review finds the optimal stock average energy demand reduction from fabric measures is likely to be 30--50%."

Reconnected on the 28th. Has started to accumulate a little heat today...

If you don't care about paying to heat your water at electricity kWh rates rather than gas, or electricity/CoP with a heat pump, there already exist some more compact (energy dense) solutions such as the Sunamp Thermino. I now have a 150l water tank with the heat pump and an equivalent-ish Thermino 150 beside it for capturing PV diversion, and the Thermino is less than half the size of the tank, and conveniently squareish, and with about half the rated standing losses... That is, where space is at a premium and DHW is a small fraction of energy footrpint then there are already solutions, including in stealth R&D that I know of!

I now run my mail (and DNS and Web ...) servers from a Raspberry Pi 3B in my kitchen cupboard, powered by off-grid solar! https://www.earth.org.uk/note-on-Raspberry-Pi-3-setup.html

With the final fiddling of the bypass valve setting, I think that the heat pump system can be regarded as 'working' and forgettable: https://www.earth.org.uk/heat-pump-16WW-control.html#2025-02-10 So, just the time to rip apart the DHW side to start to put back the heat battery! https://www.earth.org.uk/reconnecting-the-16WW-heat-battery.html

Started work to reconnect the Thermino heat battery today: https://www.earth.org.uk/reconnecting-the-16WW-heat-battery.html

As the inventor of one of those smart TRVs there is indeed typically only a very limited range over which most valve bases show an analogue response (and sometimes being in it causes undesirable noise), but yes that particular TRV does try to make use of the bit in between on and off where it can.

I use my Eddi with remotely driven boosts from my RPi: the heat pump doesn't get a look in. (I also limit the grid demand while boosting to 2kW.) I appreciate that this may not be at all what you are after of course!) All this to do smarter and less frequent pasteurisation, basically only when the grid is relatively green.

Taking the emergency out of water heater replacement — and slashing emissions: MCE, an electricity provider for three-dozen communities in Contra Costa, Marin, Napa, and Solano counties [San Francisco Bay Area, CA, US], launched a [Emergency Water Heater Loaner] program in September that offers contractors a $1,500 per-unit cash incentive for the installation of an electric heat pump water heater after the installation of an emergency loaner. The big points here are that (1) a temporary heater is only used if the main job cannot be completed in a couple of days and (2) that the loaner is subsidised. So the expectation is for a fast replacement, but with a good cheap plan B.

I am brewing up to writing an open letter to Ed Miliband and Greg Jackson saying how and why most UK domestic heat pump installs should be doable in a couple of days, such as to catch the distress purchases, and how other countries help make this kind of thing work. Some of it is not even Adia's claimed cleverness, but such dull stuff as pre-fabricating pipework etc off site to connect in seconds to the existing boiler pipework (they know the boiler brand, and where it is on the wall, so what all the pipes do) and getting pre-auth from the DNO to install one of several ASHP models depending on what the concurrent survey indicates is needed. Will not make me popular in some quarters, and obvs it's easy for me to claim not doing the work!

I'm likely missing this above but I'm too tired! Is there some sort of mixer for the UFH that's reducing the UFH flow temperature compared to the rads? If so, without damaging the floors, can you just not mix it down (so much)?

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.