joth

(Mostly to help me in upcoming conversations with the various trades) I'm likely to end up with a lot of rooms having 1 or more individual lighting circuits. (especially if moving away from DALI to centralized mains dimmers and contactors, as seems to be the recommendation) Rather than bring back 2.5 floors plus garage to a single central CU, I'd rather have a distribution "sub board" per floor, plus another in garage, and in loft for PV inverter and batteies etc. Is there a generic name for this "multiple CU" hierarchical topology? Presumably RCBOs all go on the sub-distro boards (as you want different ratings per local circuit, and earth leak trip isolation between them) and then the central board just has an incoming breaker and a number of MCBs for each of the branches? Regs don't require an RCD at that head location or anything? Any general resources anyone can recommend on specifying and designing residential "structured wiring"?

Our street is a relatively main-ish road with school a few doors down, so I'm relatively sure there would be something within a reasonable distance. It's all underground though (conservation area) so if there wasn't something nearby it would be an impossible job to run it to us. So really in order to rule this whole idea out right now, I'm interested in the what the "best-case" (i.e. it is right at the end of our driveway) cost could be vs moving an existing head. If that's way more, then I can just save the effort on researching it any further. Oh, and does a 3ph supply command a higher standing charge or anything?

Background: 1/ We need to move the existing 100A 1ph mains head (currently location will become a downstairs shower, plus opportunity to address terrible airtighness of current main feed) 2/ We need to get G99 approval to hook up 8kW of PV generation (to give away the export for free, ?) which might be denied because it's only single phase... 3/ Moving to an all electric future, possible ASHP, car chargers, etc in future mean 3 phase might be just a useful thing to do anyway. Anyone got any experience of typical costs, for: a) moving the existing head (by about 5 meters; assuming we do all the labour and termination as far as we can) vs b) getting a new 3ph supply laid in from the street (about 20 meters away; again assuming we dig the trench etc) Hmm as often the case, writing the question out it sounds obvious, but lets ask it anyway (I shot ukpowernetworks an email to get ballpark indication, but no dice -- they just sent me forms to fill at length for a formal application.)

I think Eddi one such diverter? I had wondered why it supports them sequentially only, but this makes sense. (we're looking at 8kW array I was actually researching diverters that can enable single or both coils, depending on the excess export available)

@Nickfromwales very helpful, thanks. ? This is probably a silly question, but I take it all modern boilers have balanced flue that is totally sealed from the room in a 100% airtight way? So no need to "shop around" for a special make/model or even passive house certified boiler, like folks have to for wood burners? (Searching online didn't bring up anything on this topic, so I assume it's not complicated, but I know our current elderly boiler is open flue and seems it would be a disaster for airtightness)

My counter thought is: if once is primarily aiming for the "certificate" rather than underlying performance of PH/EnerPHit, then there's no "extra points" on offer to be gained by putting the boiler inside the envelope (AFAIK), but that flue certainly adds extra risk for that all important final airtightness test? (Even if the flue itself is sealed, it's a bigger hole on the envelope to have to deal with, not to mention a bigger thermal bridge) I'm sure all will become clear when we get into the detail of PHPP anyway.

@JSHarris thanks - this is interesting. Searching online for "Constant Current LED" brings up no end of articles explaining CC vs CV principles, and invariably they seem to state constant current LEDs typically are 350mA or 700mA; it's trivial to find drivers in those ratings but LEDs themselves is much more work! I suspect I'll find more 300mA then, same as you then. FWIW - the integral one I tested is rated 6W and is about 15V @ 300mA. The thought of course crosses my mind to put 2 or even 3 of these in parallel to jack up the current I can load onto them, but that's asking for "cascading failure" trouble ...! Part of the reason I'm going down this path is an aversion to mains voltage dimming (at least, with any non resistive loads). I've had the widely recommended Varilight V-Pros in the past, with a mixture of CFL and LED on different circuits they were damn noisy, and a bit erratic to be honest. (So much so that our tenant complained, and our mismanagement agent ripped them out and binned them without consulting us, back when we were living overseas for a few years). Hence why I've got myself into this combined dimmer+driver misadventure. But I do think it will give a better result in the end. - certainly in testing so far, the whole setup was deadly quite right through the dimming range.

I'm surprised I'm asking this, but does anyone have good tips on sourcing integrated LED downlighters at reasonable prices (ideally around £15) with a known/documented constant current rating? I have a bunch of OSRAM 35W optitronic DALI dimmer drivers I picked up for peanuts, rated at 350-1000mA, now struggling to find suitable LED downlighters. Ideally 500-700mA range (to make best use of the capacity I have available). https://www.ledz.uk.com/product/ls/fixed-downlight/ look quite nice, but so called "specification grade" meaning £45+ ea. I picked up a £11 Inegral LED that comes with a 300mA driver. If I chuck out their driver and use my own it does work quite nicely (obviously adjusting the LEDset resistor down appropriately). So I'm really looking to see if there are any other "driver included" good-enough quality modules out there come with a greater current rating (ideally 500mA+, but at least 350...), and with the driver independently wired such that I can unplug the provided one and use my own? (Or even better, come with an LED-only option, no driver needed). Aurora / Enlight stuff looks good but AFAICT the drivers are all welded on, not suitable for disconnecting.

@Nickfromwales thanks for the reply. I am no doubt misusing terminology - by thermal store what I mean a placeholder for "something" I can dump heat/electricity into when it's cheap (coming from the PV, or E7/10 if we decide to go that way in future) and that we can take heat out of for DHW and space heating at other times of day. The exact selection could be SA, UVC, or a full fledged Thermal Store TBD. But the key thing is being able to bank up energy when the sun is shining, ideally enough to cover over a day or two of overcast, not for throughput it delivers. (2 simultaneous showers every day, 3 very occasionally) Back of envelope, 160m2 house will have 4000kWh annual heating requirement, which worse case (ignoring any PV generation) looks like about £200 p.a. more on E7 vs gas (using 8p vs 3p per kWh). So at today's rates the boiler should pay for itself. What could throw all this off kilter will be the cost of moving the gas head. If that's too much, it might push us over to just having it disconnected and going fully electric. Saving on ongoing maintenance would be nice too.... but it all makes me fear we'd then be obliged to get into ASHP and that's not something I'm ready for yet. (The noise, mostly). GSHP would seem ideal, except for the price.... Anyway.... regardless of what our specific design ends up, I'm still academically curious of which is "best" place for a boiler, inside or outside the envelope

https://newatlas.com/cct-silicon-energy-battery-thermal-energy-storage/59098/ https://www.fircroft.com/blogs/worlds-first-thermal-battery-could-revolutionise-energy-storage-99111535454 Edit to add: possibly the first one going into production, that can return the stored energy as electricity?

@jack That helps a lot. Obviously for majority of windows they should really be certified else the penalties would add up. But for the odd awkward one we can negotiate it. Very helpful input to be heading into detailed design with. Thank you. Yep the goal is certified EnerPHit.

Yes, by Passiv I meant PH certified, editted to clarify. This will be on a 45° roof. I was using the Fakro product selector and pricelist: the U8 seems to be the only PH certified opening windows, but they're not list on pages 18-19 with all the other electrically opening units.

We're planning skylights in the faulted ceiling over the hallway -- 2.5 stories up. It will make great stack cooling, but that means electric (and ideally automatable) opening. Velux do one, but I've heard mixed things about it so at least want to explore a second option. Fakro can do PassiveHouse certified OR electric opening, but not both together, AFAICT. Any others I should look at, or just make Velux work?

Should have mentioned, still in planning, haven't completed full PHPP so don't know the exact heating requirements. We have a fair bit of the SW face of the house is glass so we think we'll do alright for solar gain. (Certainly inspired from reading on here about using the UFH to help circulate that around the ground floor slab) But yes, if the boiler looks like it will be in use more often than on rarely, putting it inside the envelope makes sense because then the heat put out by the unit itself is captured inside the house. Still curious if it is a leaky box for airtightness. If we do put it outside the envelope, putting it in its own insulated box sounds a nice idea. The garage will get fairly cold as it's currently detached from the house; we're building an extension up to join us to it, but this will be the highest speced part of the house insulation wise (being the new-built part)

Probably some silly questions, but just getting started with water/heating design so bear with me! In an energy efficient home with a lot of solar PV, would there be a case for installing a system boiler outside of the airtight envelope? We're planning an EnerPHit home with 8kW of PV. Using a thermal store for DHW and heating (UFH downstairs; towel rails upstairs). In summer all DHW needs will be from the immersion heater, in winter it will just be on coldest and shortest days, and with lots of guests (e.g. Christmas) we expect to need to drop back to the boiler. Possible locations for boiler are in the laundry room (inside envelope, next to the thermal store) or just the other side of the wall in the garage. The garage was not a obvious choice, but now wondering about it as presumably keeping the flue etc entirely outside the envelope is better for airtightness, with just a pipe having to penetrate it. These pipe runs could be very short (straight through the wall). What I don't know is if a boiler out in the cold will have more maintenance issues, the frost prevention should protect it but might be wasteful for generating heat we don't actually need, and if there are other drawbacks. So question 1 is, anyone done this? Or, having put the boiler indoors and found significant issues with it ruining airtightness? (Or any tips for avoiding that?) Second, loosely related question: what type of boiler make sense for a system backup? Ideally we'd make it the smallest size viable for the worst-case heating requirements in winter (i.e. should be fairly low) but that might result in a long wait for a hot shower should the cylinder get emptied on Christmas morning. Would anyone consider using a combi boiler for a backup? So the DHW could flip over to be fed direct from combi instead of the thermal store when it is depleted. Downside is more complex plumbing and control system, more maintenance needed for a rarely used combi(?), and more cost. And I think this would really imply boiler inside the envelope. (Obviously in this situation we couldn't happily run all 3 showers from the combi, but I think that's a reasonable compromise). So, again, anyone done anything like that?

Bit late to the thread but GB-Sol RIS is the other one I know. AIUI the unique thing with these is, as they manufacturer their own panels they can specify them to fill to any shape and dimensions.

I've been 'lurking' around here for a few months now but thought it time to make it official. We're in planning for an extension and renovation in North Herts, with goals for EnerPHit. I found the site via searches for UFH and cooling in a PassivHaus and stumbling on a whole world of opportunities and challenges I didn't know I needed in my life! So yes you'll find me mostly posting my questions in the Energy sections.