joth

Three phase will support 2 car chargers more easily and also allow for you 5kW solar PV without the need for extra paperwork/permission from the DNO. What is the total cost of the mains feed installation? You'd have to pay that all over again (plus digging trenches/making good etc) if you ever have to add 3ph at a later date, so generally doing it now during the build is a really good idea for future proofing even if you decide not to use it initially as others have said.

Good to know. I've been buying very similar looking plugs under the 2Nice or teckin brands and using tuya-convert over WiFi, never had to physically open one up. Looks like Gosund is the going name for them now: https://www.esphome-devices.com/devices/Gosund-UP111 About the Local Bytes preflashed ones, do they have a voltage/power calibration curve preset or do you still need to do this per device? This was the most tedious thing I found about putting custom firmware onto them: each device needed it's own calibration as the tolerances between them are wide enough the readings were way out if trying to use a default configuration. I expect they have calibration numbers flashes into them on the manufacturing line but replacing the firmware overwrites it.

Just confirmed my Energy Store for installation next Friday so hopefully this will work out in time for Octopus Go load shifting onto overnight 7.5p rate.

So to clarify there's no direct relationship between the ACH used to measure airtightness, and the ACH I quoted the MVHR is operating at. The airtightness is measured at a contrived situation (50Pa pressure difference between indoors and outdoors). On any given day there may be zero difference, e.g. in very still conditions with no breeze; or there may be a hurricane blowing through. So the amount passive ventilation varies hour by hour but the active ventilation is more or less constant. All we can say is, the house as a whole is receiving 0.3ACH minimum rate of ventilation, but much more if it's windy or the MVHR is on boost. In terms of expectations: the design flow rate was 140m2/h and the measure actual flow rate is 150m3/h once everything was balanced out, so it's pretty close to expectations. But what I think what you'll find a lot more interesting is the MVHR app's claim it has saved 6.75 MWh of heat/cooling energy since install Nov 2020.

Yes, we did PHPP and obtain PHI retrofit (Enerphit) certification. The houses 50Pa rated airtightness is 0.6 ACH. Our MVHR supplies about 0.35 ACH. (Based on the MVHR app, that states 150m3/h flow rate right now, on a building of 440m3 volume) Agree with @JohnMo's suggestion to use the heat loss calc from Boffin's corner if you can, but for our project we needed PHPP anyway (to obtain PHI certification) and the MCS Calculator anyway (to get the MCS cert on the ASHP install, to get RHI) so I found it better to spend my time on making those 2 tools work for me than add yet another into the mix.

(I don't see the screen shot?) This sounds very similar to the standard MCS heat loss calculator template. We used the "Cat C" columns below, which assume 0.5 of 1.5 ach with a special note about extract ventilation. The issue with their spreadsheet is less the specific ACH used but the fact they have no calculation for heat recovery of any sort. The net result was it overestimated our heatlosses by 100% vs PHPP.

>Why don’t large commercial companies have PV ands battery storage ? Maybe not here, but the EU is working on making PV a legal obligation: https://ec.europa.eu/commission/presscorner/detail/en/ip_22_3131 A Solar Rooftop Initiative with a phased-in legal obligation to install solar panels on new public and commercial buildings and new residential buildings.

Can you explain why you had to do this? It doesn't sound right.

Silly SAP. It's very expensive and inefficient to open the windows in winter, as doing so lets all your expensively generated heat out the building. (Likewise in a summer heatwave opening windows allows all the expensively cooled air out). This was the first thing that got me looking into MVHR: I hate the wastage of open windows in winter, my wife hates the humidity and damp of closed windows.

What does the heating guy usually do for the service hatches?

My guess is you'll get cracks forming around the outline and it will look pretty naff. Have you asked your main contractor? My guess is they'll decline to do this as it's non standard and they can't guarantee the quality of the result. On the flip side, if it really does hide well, when you come to do maintenance it'll be a lot of prodding and scraping to find the crack and dig it out again. The common solution is to put the FCU in a hallway, thoroughfare or utility area, which both removes the noise from the living area, potentially allows for a dropped ceiling in that location (making the unit selection and installation a bit easier) and doesn't matter so much if there are unsightly service hatches.

Some questions to ask your architect: How important is it they use one of their regular contractors? Would they be open to a different build method such as timber frame with off-site construction that comes with a guaranteed airtightness like MBC? Will they be contract administrator to a main contractor? Are they happy to write airtightness requirements into the contract, and hold the main contractor to them? (even when they try a wriggle out claiming airtightness was impossible due to a specification error from the designer) As others mention if you know you have a good working relationship with an architect I'd be tempted to go with them, but these are some more questions that will help ensure the build itself can meet your goals too.

How many story building? I find cooling in UFH on our ground floor "works" fine but creates a pool of cool air 1 ft off the floor downstairs that does nothing to help the building as a whole feel cool. FCUs upstairs are much more effective. (Conversely, the UFH is excellent for heating in winter)

Some corporate buildings do. I plan to pop in here when I'm over there next month: https://www.popularmechanics.com/technology/infrastructure/a40050447/a-dragonscale-solar-roof-is-the-sparkling-focus-of-googles-sustainable-new-bay-view-campus/

Not listed on https://solarenergyuk.org/resource/smart-export-guarantee/ yet? They have "Agile outgoing" which pays market rates like for Agile import, which in general is a crapshoot but it means right now is good - they're paying around 40p/kWh around the times of day ppl are likely to have excess solar generation Snag is to get this tariff you can't be on Octopus Go for import. My "Go" fixed tariff is very favourable so i don't want to cut it now. It ends in Sept, so I could switch then, but that's just as solar generation starts to tail off 😕

Reading my previous post I see it's misleading: I'm not saying the Quooker is particularly inefficient in of itself. It has 10W standing losses for a 7L tank, and has energy rating A. Combined with zero wasted water running off the kitchen hot tap it is pretty efficient component on its own. It's really just the self-consumption of PV that it's not optimal for. A 1.2kW Qettle would be better, but a bimodal with a "trickle" and "boost" option even better 🙂 Oh now I'm looking at the telemetrics the element in the Quooker Combi draws about 2.3kW, not the 3kW I previously stated, FWIW.

Do you have a link to the make/model you used? GU10 I take it? Thanks

Have you considered building an upside down house? Assuming you like the living areas warmer than bedrooms, putting bedrooms on the ground floor and living areas above will give a major boost to the year round temperature balancing act.

I'd argue that was a short coming of the copper connection you used rather than a strength of the wireless. A WISP will always multiplex users onto the spectrum available so while you may get lucky and have good latency one day, an increase in usage can disrupt that minute to minute and over a longer arc it can deteriorate as more users sign up. OTOH copper is dedicated capacity to the ISP so you're only constrained by the backhaul contention ratio, which they can address much more easily than buying new radio spectrum and you can address by switching to a more premium ISP.

Ignoring all the other users in the house, is gamer boy getting good gaming experience on the ADSL? If so I suggest getting another (wireless) service in addition to the ADSL. Gaming is much better over wired as it's lower latency. A point to point microwave network will give very disappointing latency for gaming. Reserve the new network for everyone else in the house, especially for video streaming, as that needs high bandwidth but doesn't care about latency. Dedicate the ADSL for gaming. (And perhaps IP phones calls). And locking it to ADSL means there's no risk of the Xbox consuming anyone else's bandwidth. And, if either service goes down (very likely in rural location) you have the other as a backup. And zero incremental cost to you.

Got it, thanks. Basically about the data cable and high expenses of making it wireless. My inverter is right next to the DNO cutout so way easier to keep with the SE CT clamp, in the first instance. (If the damn thing ever arrives) Cheers

Is this mostly driven be a preference thing, a money saving thing, CAT5 cable avoidance thing, or do you have reference to why CT clamps would not be suitable? To my mind spending £190 on the official SolarEdge energy monitor would be very worthwhile, if I can avoid yet another raspberry pi, python script, wifi link and collection of other components needed to make them all play together. I actually see CT clamp as an advantage as it's physically non-invasive to the system it is monitoring. Totally appreciate you sharing the way you're approaching it and not saying there's anything wrong, just trying to resolve in my own mind what priority order I'll tackle the various sub-projects here in. I can see that hardwired modbus approach may prove more useful in the long run for getting API control of the inverter, personally I'll be shooting to get the basics working ultra reliably first, before trying to add that as a separate control layer (if I can).

Just to confirm my own understanding, for a system with cooling, you'd recommend a pair of 3-port valves one on each end of the UVC coil, so both the supply and return end of it are shut off and diverted into the buffer when the FTC switches over from DHW to space heating/cooling mode? Do you have a preferred make/model of diverter valve to use for this? My system is currently plumbed with the schematic attached, more or less, using a single 3 port mid-position valve for the change over (the typical honeywell one), and I've never been overly happy with it. It uses way more primary energy in cooling mode than heating mode each year, for a fair number of reasons, and I'm sure this is one contributor. (So I appreciate the chasm that can open between getting cooling to work, and getting it to work well.) Standalone with Third Party Cylinder 2ZM - FTC6.WMXXX.STP.2ZM.pdf

Fair enough. Have you already got this pre-plumbed cylinder? If so my thought now is run it with the simplest heating-only design you can, per LA3222, and if come next summer you have issues requiring active cooling do it properly and install a2a unit(s) upstairs. They're very plausible to retrofit

What floor finishes do you intend to install downstairs? - are they temperature sensitive? which zone(s) are you thinking would be used for cooling? Personally I'd install the electronic mixing valve onto Z2 and use that for the UFH, as even if it turns out you can run the rads and UFH at the same temperature, it's nice to have the option of being able to set them to different flow temps or compensation curves. Also note that this design will be fairly limited for cooling. I doubt rads will work. You'll get a bit from via UFH loops, but as they're all downstairs you have stratification working against you, so downstairs will have a puddle of cool air at ground height, but upstairs won't benefit at all. This may not be an issue to you, but for our house this is exactly the opposite to what we'd like. (Generally we want the office and bedrooms cooler than the living area, not warmer than). Unless you want to get caught up in installing Fan Coil Units upstairs, on a new build, my own recommendation would be to put UFH upstairs too. It won't add much expense compared to rads and is a LOT more flexible.