joth

This is the key bit: scrap your car and move to EV if you drive more than ~4500 miles per year. If you have very low annual mileage, like @sgt_woulds, it makes no sense. If you have extremely high mileage, then of course moving to a lower cost-per-mile vehicle will pay off very quickly (for both financial and environmental cost) We drive about 5000-6000 miles most years; I've put off getting an EV thus far because of this low mileage but as it's now 10 years old, and there's now a better range of equivalent EV available, so I should be picking up an ID.7 Tour tomorrow. Weirdly the insurance quote is actually less than my current Skoda - perhaps because this will be a company owned car (although my guess would have been that would only add to the premium). /shrug

The problem with both proposals is in a few year's time good luck finding it if there's a fault, let alone if there's a new home owner. Personally my preference is to put them all in a somewhat central location per floor, e.g. next to the consumer unit or in a cupboard with (above) ufh manifold, next to the network panel, or something like that, depends on the floor layout. (In my own projects they go in the home automation control panel, of course). People often worry about voltage drop on long lines, but upsizing cable to 1.5mm2 and always use 24V rather than 12V strip. In practice if thought out a bit the cable run will likely be under 10m anyway. You can put isolator switches in that same place for things that don't have any more obvious locations. Just makes it all a bit more maintainable.

Aside from the whacky surprise it leaves to any future electrician working on it, I'd be concerned fire alarms come with a "test monthly" sticker or similar, and this thing frobbing off so regularly will decrease lifetime of the rcbo and relay base, and increases odds it gets forgotten and not re-enabled

lol That's my gut feel too, and usually I'm all-in on smart (home) tech. However smart breakers are coming and could indeed eventually make a lot of the need for local isolators obsolete, if one actually has a vague idea how to remotely connect to and trip-off the appropriate circuit. https://kb.shelly.cloud/knowledge-base/shelly-pro-cbs https://www.infineon.com/application/solid-state-circuit-breaker Despite my scepticism I do see the attraction of having per-circuit current/power monitoring built into each breaker. And digitally tripping off circuits could be a tidy way of implementing centrally coordinated load-shedding e.g. if failing over to battery during a grid outage. But as a mechanism for home owner or handyman to randomly frobnicate circuits on/off when doing misc maintenance... I don't buy it. Just too much cognitive overhead vs having a good old switch at the location. ... btw I'm skipping over the elephant in the room for the devices listed above - at least the shelly - are MCBs not RCBO, and is taking up a double-module width at that. And I imagine lack 18ed approvals. Makes it a complete non-starter right now, but it's just immature product and totally solvable in due course. It's the fundamental usability for a safety critical application I'm doubting.

In the real world these decisions are really a dialogue, not a mandate. But can be an asymmetric dialogue if the customer isn't informed of the alternatives. Either way point is to start that dialogue early rather than push it into brinkmanship. Many self builders are not in the position to be able to fire their electrician on a whim over the position of one isolator switch, so better to have the conversation at first fix rather than after the walls and floors are sealed

It's best to check with whoever will be completing the EIC as appropriate location of isolators is in the regs and quite subjective. Ours insisted on putting them in the very nearest cupboard, which has resulted in a few getting knocked by large items being shoved into said cupboard Recently I've seen on other projects that electricians seem much less concerned these days, either putting all isolators together next to the CU, perhaps using minigrid switches, or even omitting isolators completely (e.g. for outside blinds). If they're happy signing the EIC then fair game. Pretty sure they had more conventional isolator for anything over 13A.

Yeah, you are right that if it's lower humidity (and temperature) inside then the enthalpy exchanger should help. I was thinking of the case where it's (much) higher humidity inside than out, but that isn't what we have here today Funny you ask - I was literally looking at options immediately after posting here. I'd like you that starts (or resumes) operation after main power is cut and restored, so I could easily put it on a relay switch to control only running it when really needed (and ideally, during cheap energy window), but got bogged down as the cheaper units all seem to need a push-button press to start operation, or have their own smart/cloud/app integration that I really don't want. It's something I may yet do if I find a good option. Good news is connecting continuous drainage is easy in the plant room, so doesn't matter if it only has a small internal condensate pan. In the meantime, I've tweaked around my logic to allow the FCU flow temperature to drop a bit under the dew point if cooling load gets high, and let it drop much below dewpoint if the house starts to overheat. I figure a short(ish) period of condensation on all the pumps and valves is tolerable; it's long term dampness on them all I'm concerned about for causing corrosion and parts to fail. (In all cases the UFH flow is hard-limited to not go below dew point )

Dew point in our house normally sits around 15°C but in the current weather it's been slowly creeping up, just about to hit 20deg. There's a double whammy here: the very warm outside air is a able to hold more moisture, and as it is staying warm around the clock it is gradually is doing so, raising humidity of air coming in. The system is not able to keep up with the cooling demand (ironically largely due to the dew-point restriction on flow temps - I could get it super cold if I ran it blow 10°C) so the inside air temp is crawling up likewise increasing dew point. Behind it is another irony, that we were warned force-air heating from the FCUs [which are never actually used for heating in practice] causes the air to dry out so went with an Enthalpic heat exchanger to retain indoor moisture, which is now working against us in pushing that dew-point calc up making cooling mode less effective. If I ran the FCUs below dew point for a couple hours they will of course extract moisture from the air (sending it down the condensate drain) thereby reducing internal RHI, dropping dew point, and allowing the system as a whole to work more effectively once again while sticking above said dew point. Ho hum

For an a2a system, yes definitely. For a2w I'd recommend provisioning for it if it's not too difficult, but in practice I'd always run the water flow temperature above dew point so the condensate is not needed (and actually just creates a liability of drying out and creating bad smells)

Define "effective". If you leave then running long enough, and ideally predict very hot weather and "get ahead" by starting cooling before the house is already overheating, they're extremely effective. It's what I use, and would happily specify in any build I'm doing the controls for. (But, i know i can do the work to make the home automation keep on top of the cooling demand. You don't *need* automation for this, but it takes a bit more proactive user intervention. I can't rely on the occupier being so diligent, and they may also do stupid things like leave shading up and open the windows when the outside temperature is hotter than inside) If you're more into waiting until it's unbearable then smashing the A/C into max, you need a2a AC.

It depends a lot on location (installers in expensive property areas charge more - somewhat justifiably as they no doubt have higher living costs themselves) However I'd be very surprised if you pay someone to supply & install A2W, UFH, 5 FCUs (and a DHW tank right?) for less that 15k. Not in the south-east, for sure. When I tendered my reno (in 2019) my builder quoted 8k to install just one ducted FCU on its own - without any A2W or plumbing work! That was obviously a throwaway quote for work they didn't want to take on, but still... FCUs are still not much loved in this country. If you do non-ducted / wall mount fan radiator it's probably a bit less. A decent bit less if your installer prices it as just another radiator install. Cheaper to install, cheaper to run, or ... ? If self-installing it's almost certainly the cheapest way to get heating and effective cooling. I contracting out, too many variables to say Running costs - probably the cheapest option, considering reduced maintenance load vs 2 systems, and esp with the increased TOU shifting that UFH allows. I'd always say put the UFH in, if you're doing some sort of GF slab that would accept it. Even if not connected it gives so much future flexibility. Specifically, UFH in a well insulated slab is both ideal emitter for renewable heat sources (very low flow rate), but also doubles as a large heat battery (storage heater) so you can heat it up during cheap rate and coast through the peak period. A2A really can't do that .

Maybe of interest to some people here, that would like to be on modern TOU tariff but can't get a smart meter due to lack of DCC coverage https://www.ispreview.co.uk/index.php/2026/06/chameleon-tech-uses-home-broadband-to-solve-uk-smart-meter-connectivity-woes.htm Technically not that different to what the Octopus Mini has been doing for a few years, except it sends the data to the central DCC so is supplier independent. It will continue working when you change energy supplier. Sadly it also lacks the handy MQTT interface of the competitor Glow Display IHD+CAD. There are some fairly absurd consequences of all thise: 1/ Despite being electricity supplier agnostic, this will likely break when you change internet provider (due to this industry wide failing that for most people, changing ISP changes the WiFi access point and changes default credentials to that WiFi) 2/ A rural property might: - fail to get coverage of the national DCC (despite gov funding to build it and a big drive for smart meters) - fail to get wired internet (despite gov subsidies to rural areas, and building regs requirement to prepare the house to receive it) - fail to get terrestrial wireless 4/5G coverage => Ultimately have to fall back on a foreign owned and controlled satellite internet provider to connect their smart meters to the supplier. Lets talk again about critical infrastructure sovereignty.

I connected mine from softened water, because that's how @Jeremy Harris did his. (His reasons were to avoid cost of another descaler ,and it makes a better cup of tea, IIRC) After 5 years I've not had any issues with it. Ours is a combi tank so the main kitchen tap is all softened, and we have a dedicated hard water spigot next to it, mostly used for cold drinking water We're in a fairly hard water area - borderline for being within the safe guidelines for drinking the softened water. If I have four mugs of tea (1L water) it's about the same as one bag of crisps. If someone has a medically prescribed low-sodium diet then they should avoid it still.

It's relevant for any external pipework. I think this is more common in F-Gas installs as they tend to be retrofits (in domestic installs at least), and tends to be easier by running pipes all over the outside of the building. (Ugly for sure, but easier & cheaper). I expect retrofits to increasingly use a2a for this very reason. This is the key decision point. If you're happy to pay for it, then an a2a (i.e. some sort of refrigerant based) system is the only way to get the "arctic gale" of an aircon system. Whether you combine one system with UFH & DHW or do two systems (potentially one exhaust air for UFH & DHW) comes down to shopping about, supplier selection and what they are comfortable working with. Cost wise it's probably a wash (one complex system vs two more conventional ones). A a2w heat pump with FCUs is likely cheaper to install and can perform very well (comfort and cost wise) if setup correctly. And is much more DIY-able if that's your truck. But it will never give the same frozen air blast of a2a

If you ask OpenReach they'll tell you only they are allowed to move the master socket. That detail aside... I'd say what everyone else said. Wrap some electrical tape to insulate the wires from each other before pulling back out through the wall. Else if they short they'll spark rather worryingly.