joth

We received the certificate today: EnerPhit plus. Vital stats: 0.6 ACH (target: <= 1) 24 kWh/m2 heating demand (target: <= 25) 57 kWh/m2 generation (target: >= 41) Thank you so much buildhub for a 2.5 year crazy adventure

Looks like the Pi can load a MAC address override during kernel boot. https://raspberrypi.stackexchange.com/questions/68513/pi-using-a-random-mac-address-after-every-reboot-how-do-i-stop-this-behavior /boot/config.txt Perhaps you have that set in the SD card image you are using Btw MAC addresses are only supposed to be globally unique if allocated in the global (not locally administered) range, see b1 of the first byte in https://en.m.wikipedia.org/wiki/MAC_address That said I've seen manufacturers fail to assign unique addresses even within the so-called globally unique range. If you imagine a mass produced low cost devices (ESP32 *cough* *cough*) with multiple manufacturing lines running at once, perhaps in different buildings/cities, it takes a lot more time effort and money to coordinate all the lines to guarantee each device is unique, and no MAC addresses wasted (they are a limited resource after all). Much easier to blat a random address into each device and just hope no two identical snowflakes ever meet in the wild.

Ha, wish I'd thought of this before building mine! Ideally get a small metal cabinet specifically for the 110 block termination, and have a row of strain relief (shielded) cable clamps to hold the CAT6 outer jackets and screen in place rather than having them float loose as I currently do. The benefit of this is any 'bus' protocols can be distributed entirely within the 100 wiring centre e.g. Tree, 1-wire, +24V/Gnd etc. So the number of cores coming into the LXN cabinet would be vastly reduced. I'm guessing 28 x CAT6 is you're running an entirely radial system? i.e. one cat6 per lightswitch / motion sensor / other device? This is maximum flexibility but a lot of cable. What I settled on very late in our 1st fix was that having one (or possibly 2) CAT6 drop per "room" seemed the sweet spot. My preference was to wire it to the main light switch in that room, and then daisy chain from there to all the other devices. This way the drops coming into the cabinet are very easy to label up (just the room name) and if there's any issues with any device it's very straight forward to isolate just that room and then diagnose.

Hmm 50°C seems a very high target temperature for a system based on UFH. When the outside temperature is below 5 it's going to give a very poor COP. Personally I set the curve to 30°C max rolling down to 25. Mine is controlling an electronic thermostatic mixing valve so actually setting the temperature running in the loops, and no buffer tank. So I need the max flow temp low to protect the wood floor finishes. If your system has a buffer tank and a separate manual fixed setpoint TMV then I guess the compensation curve serves a completely different purpose. (I'd really feel for the ASHP engineers in 10 time trying to understand all the different system designs people end up with, no two installs are ever quite alike.)

I used a car style 8 way fused power distribution box but you can get DIN mounted versions which are probably neater. E.g. https://czh-labs.com/products/din-rail-mount-12-position-dc-power-fuse-distribution-strip-module I think similar things are on eBay etc I also put a 20A d.c. breaker on the input to the LED strips distro board so it's easy to isolate it without shutting down all 24V distro. https://www.amazon.co.uk/RKURCK-12V-24V-Circuit-Inverter-Protection/dp/B074RK2DZB/ref=asc_df_B074RK2DZB/

@Dan F I gave this a go again and remember the error: when I try and login to the SetApp I get an error "user not allowed to use SetApp" Any idea who controls the ACL to my own inverter? The original installer I assume, or contact solarEdge? Thanks

On the flip side of what CAN be done, I have just approaching 1 year with our 8kWp array with MCS plus octopus outgoing, I've only done basic measures to optimize self-usage (immersion redirect, running white goods at midday). Generated 6340 kWh Exported 3400 kWh Export payments: £187 Money saved via reduced imports £588 (assume 20p/unit ) = £775 /pa payback System cost £16000 (GB Sol RIS) Payback ~= 20 years As domestic energy prices outstrip inflation, that time will reduce. If I can add a battery then it may reduce further. (As others have said, the motivation for us was not overwhelmingly financial gain, so just sharing this for illustrative purposes)

In other words, AC has RCDs/RCBOs but PV doesn't. Also PV has higher peak voltage, and even if the sun is hiding, DC can kill at lower voltages anyway. Juicy.

If the conduit is not entirely visible and labeled, (e.g. if hidden behind plasterboard at all), it should be armoured.

@Dan F thanks for this. I'm currently away but will try and look into all this when I'm back in the house.

Is it 14 zones, or UFH loops? Either way, I think part L requires a per-room stat on new builds so it's the default spec for most suppliers. At buildregs levels of energy efficiency, it makes sense to agressively turn off heat in unused rooms, but at near passivhaus levels it's a waste of time as, broadly, the whole house will stabilise to a near equal temperature across rooms anyway. (Yet, the complex controls are technically a requirement anyway on a passivhaus new build)

Also: Delivering 2.5kW via air is very difficult at the very low rates that an MVHR operates at. As an approximation, you can put in 10W per supply vent per °C rise (above the normal mvhr supply temperature, I.e. over and above 20C). So if you have 10 supply vents you'll need to be putting 45°C air in. The AG mini won't even reach that temperature, it would be difficult to deliver that through a matrix heat exchanger at low rates, and would be uncomfortable for anyone sat under the air vent I expect.

How much insulation are you putting under the screed? If digging out and pouring a new slab it's a relatively tiny price increase to add 50mm or more insulation under it, and will pay for itself fairly quickly. Other insulation could feasibly be added at a later date, but the under floor insulation now is your one and only chance

It's an analogy. Don't over think it! But that's not at all what the MIs say, they have a minimum not a maximum, so not sure why that's relevant. Agreed

Are you trying to chose ASHP, or decide whether to install 3phase to the house/ashp location? If the former, don't overthink it, just find the best deal on 16kW heat pump that meets all your other requirements. If the latter, maybe install 3ph anyway, if it isn't much more cost. Like a boiler a heatpump doesn't last forever, and by the time you come to replace it there maybe better deals or efficiency in using a different model that happens to be 3phase.

I think you're finding a false dichotomy here. As the previous comment says, it's possible to comply with both minimums, but taking the larger of them as the limit. By analogy: my car has a maximum speed of 120mph but the road outside my house has 30mph max limit, which one should take precedence, MIs or 40 year old regulation?

Phew. When our vented stacked was forced into the design I raised this concern, our passivhaus consultant spoke with the building physics/thermal bridge consultant and they said it should not be a problem in practice. We filled the void with as much rock wool as it would take and haven't thought about it again really. Upstairs it goes behind the ensuite, the master bedroom of which is pretty consistently the warmest room in the house, so I'm not stressing it.

3. There are 3phase SMETSv2 smart meters, they call them "polyphase" meters in the spec, searching this site for polyphase brings up lots of info 4. Yes Octopus do, no extra charge, but people generally find it's much longer wait times that single phase +1 to getting UKPN to answer the rest of the questions.

Terribly. Don't bother trying. pairs out of a Cat6a cable was my solution. (Assuming you mean the wago 243 terminals)

I also used those. The bootlace ferrules are needed when used in screw terminals but not in the spring loaded Weidmüller terminals (which can take max of 1mm2 IIRC)

No! It's a good question, I was hoping for an easy answer here rather than have to do that. Ah good thought, I think it could well be something along these lines. This is the UFH flow temp at the same time There's a small slug of 23ºC water at the moment the DHW turns off 01:17, then at 01:52 it starts running the UFH proper. If for some reason that initial slug is just as the electronic mixing valve shuts down, it will indeed take a bunch of time for the water to cool if it's just circulating in the primary circuit and low loss header. (I definitely wish we'd put a large buffer tank in, as then this would be filling that up, rather than most likely being wasted to outdoors in the external pipework.) And again I think you're right that running the DHW at the end of cheap rate is going to be the only/best way to solve it. I've not programmed it to do UFH first and if that reaches target it will do a "boost" on the DHW. I need to program in an extra test that if the tank middle stat temp is too low (below 40?) it will force override the UFH with 30mins of DHW from 0400-0430 Thanks! No it's driven from Loxone miniserver relay outputs, so I can make as complex control logic as I care on all this. (Although trying to KISS as far as I can, future me will be grateful for that)

So on top of the first floor flat roof? Does sounds ideal in many ways, but can see probably needs special access/handling HSE procedures to install, and you'd want some sort of flat rood hatch and "loft ladder" to get up there for service from time to time. Have you had quotes from other installers?

Technically, if it's a new-build you have to have WRAS everything, but if you're renovating you (probably) don't. If your mains has already been hooked up to enable the build (as most are) the odds of it being retrospectively checked are low, but technically the liability is there e.g. for when you eventually came to sell. (Heck, it's just a tap. Odds are you'll replace it again some time anyway)

What is the layout upstairs? Have you considered options to wall-mount a monoblock higher up? This would reduce the pipe distance needed but obviously might have some aesthetic and access drawbacks.

My very rough understanding: it's fine for all the "inside the house" vertical stacks to be purely on AVVs, so long as the horizontal drain they feed down into has a open-to-air vent at its furthest point from the main sewer. Typically this is done by extending the horizontal drain right through under the house and out the other side. The open vent can be down in the garden somewhere or whatever. But different BC might see it differently. We were going to do exactly this, but my main contractor removed the vented extension and got the architect to approve the change, and then poured the slab without telling me (this was last April, and I was bed ridden and in quarantine with 'rona). Their argument was because nothing was feeding water regularly into the open vented end, it would slowly get blocked up with "back splatter" at the point the furthest upstream vertical stack drops into it. They debated swept bends, but never considered the obvious option that our extended pipe was going out to the garage and passed an outdoor tap we could have fed the drain down to it to keep it cleared out. So anyway in the end we had to punch an extra hole through the roof so our final vertical stack can have the open vent on top. (They tried to charge me extra for that variation, so I asked for the money back on the horizontal pipe and foundation lintel they failed to install without my approval and they backed down ?)