S2D2

Quote seems a couple of grand heavy, might be worth getting a few more but prices are getting a little daft atm. Remember it includes a whole bunch of other kit, mountings, cables, scaffolding etc. And will give you an MCS certificate to get paid for export. Even with your high usage you may end up exporting a fair chunk.

The idea being (I think) you can convert the outside air to absolute humidity then calculate the relative humidity once you have raised it to internal temperatures. This gives you a "best case" relative humidity if you were to add no moisture at all. I think in your case it comes out at 72%, you are adding 9pp from somewhere which seems perfectly within the bounds of evaporating construction moisture or even just general household usage. Heat the room or run a dehumidifier and it will stabilise. I've been looking at this on our house and we were sitting about 13pp above best case humidity due to drying clothes etc. Dehumidifier reduced it down to 55% within a week.

The £650 application fee for G99 (depending on location) is a big disincentive. OP may have split panels East/West or otherwise not optimally placed which mean gains from upgrading would never pay this (plus the inverter upgrade cost) off. All depends on individual usage, it is a shame a 3.68kW inverter wasn't put in originally though.

Doesn't sound normal to me, suggests a very quick air change with outside air. A wireless thermometer would probably reveal the source, check window vent, sockets, light fittings etc.

I've used loft legs, the XL version and they worked very well. Shouldn't be too expensive if you buy by the box rather than individually. Remember they can be spaced at 600mm along the joists, but yes the 400mm joist spacing will increase the number required in the other direction. Use the expensive screws which don't require pilot holes and self countersink, they pay for themselves in about five minutes and make the job very quick indeed.

Calibrate beyond a fixed scaling? I can use that for a certain device but I presume it will be different between devices?

Annoyingly I've been using a Meross equivalent for this but after recently comparing with real time smart meter readings, I've discovered they're giving a reading of 200W for a dehumidifier which is actually drawing 160W. Pretty useless then. Are the above more accurate?

+1 for LVT, I used quick-step and I'd do the same if I did it again.

Assuming a loft installation your only real option for a standard house design is the upstairs landing. It is not silent so you don't want it in a bedroom and you want to create a pathway from input to extract, usually in bathrooms, so it can't go in those either. You can usually get quarter baffles to stop it creating a draft in a particular direction if it is at normal ceiling height and one aspect gets more usage than the others.

Yes I haven't done the calcs just rounded up, it does seem to be a suspiciously linked rate - I guess they want to incentivise against gas offset otherwise they'd have less export to sell off and so less clout on the market. I guess the innocent explanation is just that gas and elec rates will always be linked at around these ratios. From an eco perspective I'd rather offset gas usage but will save the hassle for when rates drop.

I use this setup to good effect. It depends on airtightness, ours is too poor to warrant MVHR running costs (probably, based on many assumptions...) Unsure on building regs, our last house was a new build with PIV and no trickle vents so it's possible.

Whilst usually true, I assume this is an MCS install so eligible for the current 15p octopus outgoing export rate vs ~11p gas offset? Obviously this rate can disappear overnight so an immersion divert may be a longer term plan, especially if it's part of a negotiated recompense as suggested above.

Interesting figures, I recently looked at this on our house with 13 months of DCC smart meter data compared against heating degree days from a local weather station (https://www.degreedays.net/). Regression fit for input kWh to degree days, input both with and without hot water (some energy lost to the drain). Came out somewhere between 4.1 and 4.7 kWh/hdd. This is a mid 90's house with some insulation everywhere, but nowhere near modern standard and poor airtightness. It'd be interesting to get a range of figures from different types of housing. Also, the point of me doing this is that you can use the average forecast temperature for the following day to work out how many kWh heating will be required the following day, allowing a PV divert to power a heater without over-heating the house. I'm yet to get this set up and am unlikely to bother until export rates drop as my heating is still mains gas.

I installed something like this as an experiment at the insulation layer of a duct run and unsurprisingly it makes an annoying noise when it's windy outside. I will move it to after the inline fan and report back if it's still a nuisance. Sadly a 100mm pir plug is not suitable, no matter how effective!

I was surprised when I checked the agile rates and they'd dropped so soon after the 15p fixed increase so maybe it's just a blip, depends how many of their customers swap over I guess, probably most will ride it out. I had assumed rates would stay high for two years. End of the day it only makes 2 years difference to the system payback so not a major issue. I don't have time for the power cut scaremongering, nearly laughed at the solar installer when he offered a £1k upgrade for an off-grid switching system, we'll do just fine without.

Thanks for the feedback, it does seem like a revert to 7.5p is inevitable unless winter price rises kick in soon. Time to revisit the PV forecasts.

41W, 67W including fridge freezer. It used to be 27W before some convenience additions. I have no use for a printer or Freeview box, on-demand covers everything. NAS is very low demand so is just a hard drive on the raspberry pi. @ProDave measuring each device would be useful, without knowing details of your setup I'd guess spinning disk drives make up a good chunk of the power draw, SSDs would reduce this. The problem with off grid is 100% availability and diminishing returns, the capital investment to absolutely guarantee this circuit doesn't go down for a few hours over a few weeks of winter would probably negate any savings. I would be interested in the performance of the very cheap wind turbine mentioned though. Edit: Just noticed the mains charge backup, this may make the system viable if you assume something like 25% will come from the mains charger, counteracting the diminishing returns

How are you finding the October rate? I've just checked and looks like currently the 15p flat rate would be better? Haven't done the sums over the month yet though.

My chosen solution for a similar situation was PIV - I couldn't justify the running costs of MVHR with such a leaky, albeit reasonably "not too bad" house. I have block + beam + block walls so was less worried about moisture escape, though my previous house was timber frame and used PIV to similarly good effect. Installed above double height stair void and temperature is vaguely noticeable when passing but far warmer than outside on a low setting and nothing that makes me wish it wasn't there, I don't loiter on the stairs. Air quality much improve at a subjective level, I never bothered measuring it as I considered the problem solved.

As usual it depends, but probably if your focus is maximising return on investment. Optimising for offsetting your usage is more nuanced and requires you to factor in consumption, as in the thread I linked. This has the benefit that you'll be reducing that usage for as long as the system lasts, whereas export rates can disappear overnight. For my usage and proposed system preferring increased winter generation leads to a better usage offset but optimising for total annual output is more financially beneficial (at current rates and MCS install). It depends on your priorities.

On my units about 2mm, dictated by the thickness of the little rubber dampers that sit on the non-hinge side and make the door close silently. The hinge is adjusted to match this so the door sits flat.

I should probably have qualified further, I was comparing SSE vertical mounted (gable end installation) to 35° WSW (roof install) so a bigger difference than your comparison. Based on your data carry on with the optimal pitch. Also worth noting that if you plan to export at current rates (£0.15) it tends to dwarf any other small optimisations to just maximise total generation.

Strange that air fryers are so popular this is how things are branded now - as far as I can tell it's just a fan oven/microwave combi. I have an AEG one, works well as a microwave or a fan oven. It can do both at the same time but we never do, microwave hot spots aren't helpful for a dish that calls for oven cooking in my experience, though I haven't experimented much. If you cook a lot of jacket potatoes then maybe. I got it to avoid having a microwave on the worktop and to act as a second oven when required, which it does well.

If you have a DCC connected smart meter, see here for sizing the battery: I was looking at panel orientation rather than E/W split but found when using a battery vertical mounted panels saved the most on energy bills for my specific location/consumption - you sacrifice summer export to generate more in winter. Same principle here with south facing panels generating more in winter, that will have a much bigger impact on energy bill savings than extending the generation window slightly when the system has a battery.

Yeah that's why ours is left on the worktop with no lid, not the best aesthetically but way less faff, just chuck things in. We have one with a removable inner shell so fitting a new liner is very quick and looks neat. Milk etc wouldn't work with that though so if the newer waste disposals are better (as others have said they are) it may suit your usage more.