Radian

In the case where the device is powered from your dedicated immersion circuit (which it should be), you'll have an MCB and double pole isolating switch which you can throw and safely mess about removing and replacing the unit. If you want to of course. However, I'm thinking about how it has failed for a moment. From your description, it sounds as if everything's fine up until the moment excess solar PV becomes available. The only way it 'knows' this is through the current clamp which detects a net export to the grid. The first test I can think of would be to unclamp the CT and confirm that all the lights are normal even when excess pV is available. - If it does misbehave that'd be extraordinary and something weird is going on with your inverter. Next I would put the clamp back on and 'disable' the immersion by setting the thermostat lower than the HW temperature and then see what happens when excess PV is available. - in this case It should try turning on the immersion but with no load there, it would be interesting/informative to know if the lights go weird or behave as normal.

Good grief. You say it worked for 12 months, does that mean it's only just out of warranty? Given that you wouldn't know it had failed until it saw some solar I'd argue that it failed before the warranty was up if it was close!

It's an interesting field. I once got in a big debate with a bunch of religious fundamentalists (pointless I know) who insisted that god must exist because how else could intelligence exist. I pointed out that, at the time, Genetic Algorithms were starting to be used to produce 'intelligent designs' by iterative techniques. They argued that it took a human intelligence to design the GA therefore anything produced by it was a product of human thought. But if the product is novel - something never before considered by a human thinker, it demonstrates that designs can appear to be derived intelligently but at the same time be decoupled from thought or intelligent consideration. It totally satisfied me anyway.

In case you don't already know, if you've got a smart meter, your energy usage (particularly Gas kWh consumed every 30 minutes) can be accessed by signing-up for the Bright App. Bright would love to sell you one of their Zigbee intercept dongles to let you access the traffic between smart meter and IHD but generously make the pooled data available to energy suppliers available to domestic users using the same app.

This is only for initial commissioning - they want to see that the current clamp is seeing import i.e. it's the correct orientation on the supply cable.

^^^ Important advice that. Don't copy the way the old slabs were laid by plonking them down on dollops of mortar. It's a terrible shortcut that has all kinds of bad repercussions.

Excellent. Would have been over-engineered if they'd used an analogue sensor for a go/no go switch.

Would this go along the edge of the outer wedge gasket? I hadn't considered that. Is there a safe way you could put up a photo of the outside gasket? I don't understand what the issue is there.

I keep coming back to this idea, it appeals because it would solve the airtightness issue alright. However it's a one way shot with no comeback if there's any problems. I understand your hesitancy. With expanding foam there's no going back. With mineral wool - forget it for an exposed location. With EPS beads, on the other hand, it's the lightest intervention imaginable (no pun intended). Your concern about large holes in the inner skin are no big problem. The installation crews have seen it all before. I had an escape from the end of an internal cavity wall where it (didn't) meet the underside of the roof but it just made a neat pile in the soffit. I might get around to hoovering it up some day but it's bonded so not blowing around.

Have you considered using a UPVC gap filler like this? Worth a shot for the time being.

DRV5053 is bipolar analog but what circuit does it feed in to? It might have been digital. Biasing resistors and a comparator would be a big hint that it was analog as you suspect.

The HW cylinder and buffer appear to be in a cold loft space with minimal OEM insulation. Could this be why it struggles so much?

Are you certain it's a Hall-effect sensor? W9 prefixes a lot of sot-23 Zener diodes. No other matches that I can find. Maybe trace out the pin connections for additional clues, Vdd and GND are on pins 1 & 3 and output on 2 for all the ones I've come across but if yours looks different, it might help eliminate some obvious candidates.

That basically makes it a musical instrument.

What's the timescale of fitting the AAV relative to the date you took your photos of the condensation? With so much water vapour entering the loft from emptying baths etc. I would expect it to take days or weeks to get humidity levels back to normal.

How is the stack terminated then? Presumably you noticed this when looking around in the loft so was it open to the atmosphere? If it was, apart from the smell, it'd be a massive input of water vapour when carrying bathwater!

The condensation seems to be forming on the back of the roofing battens (regular horizontal rows). That would make sense as they're presenting a cold surface tight to the membrane and also blocking the breathability of the membrane in that place. Fairly normal. What's a bit puzzling is how this is all happening at 5oC. While it will certainly be below the dew point for air in the loft, the amount of water vapour up there is considerable. Cold lofts will occasionally see conditions where the elements conspire to create a significant amount of condensation but over the course of a year, it will generally work out. You may just have decided to look at a bad moment (prolonged moist, warm air mass suddenly replaced by a cold spell - look at local weather stations to see what's been going on lately) or there's some serious air leakage from below (unsealed extract or plumbing pipes, downlighters in upstairs rooms, poorly sealed loft hatch).

It depends on the location of the ventilation apertures. If they're openings in the underside of the soffits then insulation might have compromised them. If they're like trays sat on top of the fascia boards, under the first few rows of tiles then so long as you can see the opening at the top of the tray above any insulation then it won't matter if the eaves a fully stuffed. All I can see is a black strip low down - is that a tray or more saturated membrane?

Oh, I wasn't expecting anything quite so saturated. What sort of outside temperatures were there when you took these photos? There's a shocking amount of condensation that will form in a cold loft. I'm sorry to say it's never going to be a good place to store anything.

At last, a good application for E-paper

But that's a very specific, small, amount. Why not just say zero if a few more sunny days would be all it would take to cancel all costs?

It certainly looks like condensation and should clear up with improved ventilation. I don't understand the first photo though - what's the black membrane coming just past the rafter? The grey stuff looks to be breathable but I don't know what the black stuff is. A point about your boarded area: is it laid directly on top of the truss chords (horizontal timbers spanning the top of the house)?

"Home is rated A, with running annual costs reduced to £11 thanks to the solar panels." Er, that's got to be BS surely? Annual means getting through winter with weeks where there may be no solar. £11 of gas is 100kWh which won't meet the hot water demand alone.

That's all it can be, as those LED's have just red and green diodes. They're either both on together or rapidly switching from one to the other. Sometimes the LED can only light one colour at a time (inverse parallel diodes) but from this photo of the Solic200 PCB, I can see they're three-terminal LEDs so can indeed both be on at the same time. Seems like a fault. (Like @ProDave said 😃)

Been there, wondered that. Not found anything particularly useful. You could just poke your neighbours addresses into gov.uk's find energy certificate website and see what improvements come up for their properties - and see how different houses are assessed.