joth

We have two CO2 sensors but they're both on mains PSU and log to a PC so would be useless in a power cut. Having one with a display and battery certainly sounds sensible. Also I've considered a small UPS for the network router and switch. Adding the MVHR onto it would actually be fairly easy as they're both in the loft.

FWIW this is exactly the route I ended up taking. I have a 1-wire thermistor in each room with wood (bamboo) finishes, sending data to loxone, and it cuts off the call-for-heat if the temperature gets too high. It also can dynamically adjust the flow temp, e.g. use a high flow temp when the screed is cold and gradually back it off as the screed warms up towards the limit. I have all the logic for that implemented, but it's pretty flaky controlling the Ecodan FTC6 via their MELcloud Wifi interface, it would be much better done over the modbus interface but unfortunately you can't have both interface modules on a single FTC6 so meh, I just don't bother with this level of flow temperature control feedback. ... if i left the ashp on 24/7 it wouldn't be interesting anyway, but the nature of overnight cheap rate (and solar PV) does make it more worthwhile to back off the temperature then blast it as hot as possible during the cheap rate window

The end for new applicants. For those already in it, it will drag on for another 7 years of paperwork to claim the ongoing payments.

I know exactly what you meant. We spent silly amounts to get Passivhaus Enerphit plus certified, but still rocking EPC D On the upside, 6 more weeks and RHI perverse incentives will be no more.

We have 2 people working from home every day, working in tech, so have quite a few PCs and laptops and monitors on most the time, which come to a couple hundred watts. The lower power modes really should be better, and I will get to looking at this again some day (we go through phases of getting it tuned to power down/sleep nicely, then the employers push SW updates and it all goes to shit again). My main home automation server needed for CCTV and running most of the house is 40W and the fridge/freezer is A+++ so base loads that are "part of the house" are not insane.

For the time being, I can sell solar at 7.5p and buy it back at 5p (Octopus Outgoing vs Octopus Go) so for the big power consumers that I can move to overnight it's really not worth buying battery. I'll keep with that as long as it lasts, hopefully by the time they discontinue it batteries will have reduced in price a bunch more. (Also, there's a lot of base load usage I can't time-shift so a battery maybe justified for them alone at some point)

+1 to this. Side comment that 600m of 240V from kiosk to house will be less efficient than the high voltage distribution to a transformer nearer the property, and you'll end up paying for most of those power losses (behind the meter) rather than WPN. Oversizing the 3ph cable from kiosk to house will minimize this, as will distributing loads across the phases. Also any solar PV that reduces import will improve the overall efficiency - so long as it's on the same phase(s) that the consumption is on.

It's changed. several success stories here (and other threads) :

it maybe worth getting yourself 3x 100A main breaker and have BG them install them after the meter. Then your electrician can hook the breakers into the CU. This makes life a bit easier if/when any changes are needed to the CU, no need to open the meter to disconnect it. - Some meters have a main shut off built in, but not sure any 3ph smart meters do - Some suppliers will automatically provision breakers after the meter, but not all will

Several folks here have got Octopus to install 3-ph meter recently, e.g.

Just to clarify, 2 ACH is still considered extremely good by UK building standards. The sort of thing you have to work hard to achieve, not something that will happen by acccident because you never put any thought into it. For a conversion, you could probably have 10 ACH and still pass building regs. So unless you're planning to set a target and hold your contractors to it, I'd get a [much] worse worst-case model done. Me, I'd set a target and intend to meet it! Less that 1 ACH is a good one to aim for. Plan in to do a preliminary air-test before 1st fix starts, and if you're way off either do remedial work, and/or adjust ASHP sizing to match.

By chance I just got an email from GBS saying they now offer installations nationwide: https://www.greenbuildingstore.co.uk/services/mvhr-installation/ We used Enhabit - now part of GBS - for design supply and install, and they did a pretty OK job. We did have to get them back in once to fix a bunch of stuff it was all done without too much drama.

I would say that plays absolutely no part in it. Again, to clarify: this is likely true when using direct electrical heating (immersion heater) only Anyone attempting to charge it from an ASHP would do well to have an installer that understands how to get the two to work together.

Personally I'd use type 100 cable, I liked the Webro WF100 but e.g. https://www.cef.co.uk/catalogue/products/488397-pf100-satellite-cable-black-100m is CAI certified . If you're going to the effort of installing coax at all, the extra 16p per meter for quality low-loss WF/PF100 cable seems peanuts Some rambling info on the differences on these pages https://www.webro.com/rg6-sdu-cable-cai-approval/ http://www.stevelarkins.freeuk.com/digital-coaxial-cable.htm https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=60442#:~:text=The real difference is the,and fits F connectors properly.

It's not just that the external outlet will defeat all your airtightness work, but you need a balanced flue of somesort, or some other hole in the house to allow a corresponding inward airflow. Wherever you send the dirty expelled air to, you need to think about the return route for replacement air to makes its way back around and into the intake side of the vent. Really in an airtight house I think option 2 is your only bet. Perhaps you can combine it with Option 1 to a degree - vent it out over the top of the units, and also through to behind the fridge. Or vent it out over the units and also put a concealed hole above the units into the ceiling, and be prepared to cut another ceiling void outlet grill somewhere if needed? On level 3 your hood is about the same as our Bora Pure X max (548 m3/h) and we have that venting out via about 8m long x 10mm tall gap around the island and it doesn't make any noticeable noise -- just aware of it from the cool draft on bare toes. Remember this is only an issue when the hood itself is on full whack, which is not silent by any stretch, and you probably have something fierce boiling/frying at that time too, so it's not exactly going to risk disturbing an otherwise library-like atmosphere.

I wouldn't hold this against SunAmp: a standard UVC hot water cylinder and even an electrical house battery require the same compromise/ trade off to charging strategy The other key issue discussed at length (but only indirectly mentioned in the OP) is heating from an indirect heat source, esp ASHP with the lower output temperatures, has some technical challenges. This has been partly solved by them introducing various new PCM types, but last I looked into it a much larger issue was SunAmp had to individually test & qualify each and every ASHP controller to ensure compatibility, and in many cases they needed to physically ship out a different SunAmp controller board depending what ASHP you wanted to hook it up to. Has this situation changed at all? It seems a crazy and unsustainable business practice. Obviously not an issue for anyone keeping with direct electrical Sunamp charging only.

This is what my MVHR control looks like (sensor.mvhr_boost_request is set true when the Hob is on, the showers are running, or a triple click on a bathroom light-switch indicates a big one has dropped)

Octopus have just increased their fixed rate SEG export price to 7.5p/kWh which moves the needle a little bit in making battery even less economically justified for me, and also flips the self consumption incentive: it's better for me to minimise my PV self consumption and maximize export at 7.5p and then buy it back at the overnight 5p rate. "We’re increasing your export prices from 5.5p / kWh to 7.5p / kWh, a total increase of 36%."

The RHI application is extremely vague on this point, during sign up it has a warning that if you make changes to the house that may impact the EPC you may be required to get a new one done, but no indication as to what could actually trigger that or when. And as Ian said above, even if it were triggered I could get a fresh EPC done today but absolutely nothing (except pride) obliges me to provide the assessor with our actual insulation or airtightness numbers thus the up to date EPC would still payout higher RHI than if a fully informed EPC were done. The only reason I persevered through the ridiculous green home Grant application to limit impact of these RHI vagaries. At the end of the day anyone thinking of gaming the system by getting a crap EPC for RHI then renovating to passivhaus standard will end up paying of order 10x in VAT on their eco measures than they score back through the delta in RHI, so with both the government coffers and the environment benefiting from this devious intent, it doesn't smell like the moral crime of the century.

EPC F I guess? So long as it says no improvements (loft or cavity insulation) are needed. It's a function of heating demand, so the bigger the house and the worse it is insulated, the higher the payments. Against that, having a low design flow temperature on the MCS certificate also increases payments, and a bad EPC is going to lead to a high flow temperature needed, so maybe in practice there's a sweet spot around EPC D somewhere but it'll vary on the specifics of the build.

If you have an AOV that probably makes sense, but with a glazed window I thought you'd want it in the loft to get the benefit of the light and solar gain in winter. AOV aren't much on my radar as it's hard to get airtight / high U value, passive house certified ones? But makes sense on a non-certified project. Displacement ventilation sounds another way of saying stack ventilation? Either way it's using the chimney effect ?

Going OT for this topic, but if you're thinking of KNX light switches (and dimmers?) I'd definitely recommend considering Loxone for the heating control, and it's ~easy to link the KNX systems into it if you decide you want to combine systems as you get comfortable with it. This might be quite a nice system with lighting being autonomous to Loxone, but available for automations if desired. As @Dan F says it'd be quite a fun project to tune the heating system in loxone, and a lot more accessible for DIY tuning over time than most of the KNX homeservers (Gira et al) appear to be

Same: no special kit, extracts into the island central void and then down under the units and comes out through the plinth, about 6m perimeter so fairly low flow rate all round it.

Good point £200 for a new cylinder, and no part P electrical work needed, or you can even grab an eBay bargain if it's just for a few months https://www.ebay.co.uk/itm/325014289052

(To confirm, by "tank" you mean the vented hot water cylinder?) The cold water comes in at the bottom, and hot water leaves via the very top, to promote stratification. For the shower install, you can do it all except hook the new run into the consumer unit. If it's a demolish job in 6 months, maybe you can run the new T&E cable clipped in place but so it's visible, and the sparky that comes to hook into the CU can inspect the whole run and sign off the whole install. Worse case they'll charge you for re-terminating it to the shower. (And putting right any other critical issues they discover ). Ask them first though, it maybe easier just to have them do the whole lot. An 8kW shower on a 60A main fuse is fine, modulo what else you run at the same time? If you have a gas cooker and not many other high power electrical devices (kettle? microwave? hairdryer? plugin electric heaters?) then I can't see an issue. 60A is 14kW