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From what I remember it's Heating demand < 15 kWh/(m²a) or Heating load <=10W/m². That said, I'd i) try to understand why you heating demand is not lower ii) ensure there is a bit of a buffer in the numbers ideally

It would get kicked off site in minutes for H&S breaches. it is pretty cool tho

Self use is king. Since i installed my PV, I have exported 334kWh. If I had been paid for that at 5p I would have been paid £16.70 Even some of the more realistic rates like 15p would only have earned me £50.1 I will let someone else calculate how long it would take to repay the "MCS premium" to enable me to claim that pittance.

I wouldn’t make any decisions on renewables based on SEG or any other scheme the Government sees fit to come up with. My plan is still to consume as much as we can generate/store. Any payments for excess will just be a variable benefit.

42 years ago when I studied Automotive Engineering, we were offered a choice of modules, one was Vehicle Electronic Systems. None of us picked that option, much to the relief of the lecture who admitted later that he knew little about it. Chatting to an old colleague at my old college, he now teaches a course about servicing and repairing EVs. Has been doing it for about a decade. Eco-Drive has been around about 20 years. http://www.eco-drive.co.uk/ The guy who set it up used to run around in a little Peugeot 106 Electrique, he could get from Penzance to Truro in it.

Chofu-Operating-Installation-Manual.pdf Key difference is how they use the controller and generally connect it all up. The manual attached is very similar, just lots of pages longer and features cooling also.

Thank you all. I poured some tap water over it for a few minutes to de-ice it. Only a couple of fins are bent ever so slightly. I hope this doesn't impact on it working as it should? Thanks

I fitted three electric towel rails at my last place and the instructions said to leave the top vent open and heat the towel rail to it's maximum temperature collecting the liquid overflow. Then let it cool down and close the vent.

Yes, and it gets worse as the temperature reaching the mixer falls as the tank empties. For those not familiar with how this works, the issue here is that you're effectively using the heat of the drain water to preheat incoming cold water. The "System B" approach involves you only heating the cold water feeding the shower. The closer the incoming hot water to the shower is to the target output temperature, the less cold water you need to mix in. The edge case is where the hot water is supplied at the target temp: in that case you'd get no recovery, because you don't need to mix in any cold water. It's not all bad. If you're using less cold water, then what you are using should have plenty of time to absorb heat as it passes through the unit. Since it's warmer, you'll need to mix in more of it (and hence use less hot water) to keep the mixer at the desired temperature. I can't remember which way around they go, but System A and C involve preheating the cold feed to hot water tank, or cold feeds to both the tank and the shower. Preheating both can offer higher recovery rates - probably quite a bit higher where the average tank temp is lower due to being heated by an ASHP rather than a gas boiler. Annoyingly, I allowed our plumber to talk us out of connecting the cold feed to the DHW as well as the showers, due to complexity. For others reading, it's imortant to go for this type of connection if you have a low temperature DHW source such as an ASHP. One other thing: other than through the worst of the winter months, our immersion diverter often heats the tank well above what the ASHP is set for (50 degrees at the moment). On Wednesday, for example, the tank reached 63 degrees. In that situation, we do get more waste water heat recovery. Obviously this is much more common outside of the dark winter months.

Not sure that's right. It's not going to happen overnight but if it needs to happen, it will. Take the comments made about plumbers and ASHPs. I know 2 plumbers and they struggle with basic conventional heating system controls using a timer/room stat/zone valves. They've got little chance of being retrained in a field they already struggle with and theres next to no chance of the understanding the workings of a heat pump and associated control system. On top of that they have no chance of fixing a poorly specified system that needs a redesign. What we're going to have to do is wait for a generation of young trainees that cut their teeth on heat pumps and more complex controls to find their way into the market. That's years away but they will get out there in time.

i'm going to need to drop a ceiling in the basement to cover the MVHR pipes and other things. i look forward to seeing how yours turns out. i was thinking some kind of metal frame could be used? other option was joist hangers and timbers? it is a long way off though but my mind turns to it occasionally.

I got mine back today. Paid in full. Submitted mid May

We installed WWHRS but there is a gotcha to be aware of: The simplest way to install WWHRS (System B) is where the cold feed feed for the shower goes via the WWHRS We knew this wasn't the most efficient approach, but the plumbing for the other approaches (System A or C) wasn't nearly as practical given the showers aren't particularly close to the hot water tank. Also, looking at the data the efficiency data there didn't appear to be a big difference either. The reality though is that with System B, the efficiency of the WWHRS is directly related to your UVC temperature. So, if your UVC temperature is 48C and it reaches the shower head at 45C, the WWHRS is hardly recorving anything at all. (The efficency data I looked at was, I beleive, assuming 60C hot water) So, we now have an interesting question, which I haven't tried to answer: - Should we heat tank to 48C, get better COP and not get hardly any savings from WWHRS - Should we heat tank to 55C, get poorer COP, but recover save energy by recovering heat vis WWHRS. The way to avoid this is to use "System A", but it's too late for us to switch to this now and it's a lot of plumbing to do this for 3 showers in different parts of the house

You could fill with yellow grout?

It is the burning of hydrocarbons that is the main global problem. The secondary problem is the geo politics. If energy was as expensive as many claim, why are there so many cars, and large cars, on our roads? I just filled up with diesel at £1.69/litre, roughly 16p/kWh. Am now having a coffee, it has 0.021 kWh of energy, cost £2.95. £140/kWh. I really am a (expletive deleted) for buying it.

I highly recommend the BBC "How they made us doubt everything" podcast. https://www.bbc.co.uk/programmes/m000l7q1 - the essential argument is that oil and CO2 today is the smoking of 20 years ago - with oil companies making huge active efforts to sow doubt about a causal connection between our lifestyles and climate change. It's depressing listening, but well done. Also, if you want current data about grid electricity CO2 impact, look at this app: https://play.google.com/store/apps/details?id=com.carbonintensityapp&hl=en_GB&gl=US&pli=1 -

My architect is doing a detail for me so will share on here when I get it.

I would be surprised if anyone would admit to supporting labour 😂

Bifolds are basically poor for airtightness I’ve fitted quite a few different makes and most rely on toe and heal of the glass for adjustment If the doors are fitted level and square most manufacturers will provide 2-3 seals Each a couple of mil bigger The fitters like a nice easy clean fit and arnt usually bothered over airtight ness From your point of view you need the door to grab like a fridge door My neighbor had a door fitted by Duration and complained of drafts underneath I rang them and they sent me two new seals The first one made the door difficult to open The next worked perfectly My neighbor said whilst the draft problems are cured The original one was much smoother Probably why the fitter used the smaller seal

Nah, not really. It's an emotional starting point. We don't want to be off-grid, but we'd like to not need it. We've got a 3 acre field next door to try and provide as much permaculture food security too. Part of the rationale is to do my best to leave something to the kids and descendants that will be a 'safety net' of sorts - so they don't need to pay for rent, electricity, very basic foods, etcetera. Yep. I'm just at the start of figuring everything out, but I was figuring a few powerwalls or equivalents. Annoyingly we've got 112kWh of storage in the two cars, but neither does V2H It's a 22m long barn with a south-facing roof - that's also ignoring the other building, which is on a north/south alignment. Yeah, there's already a three phase supply to the property. I'll need to figure out what goes on what phases, and all that jazz. I'm just at the beginning, really. Yeah, we might have to register as a power plant (I can't remember what the technical term is). It's something we'll need to think about, for sure. Agreed. Asking on a Tesla forum, others have done similarly complex systems, and unfortunately there's no decent book on the subject.

I'm not sure whether you mean a literal PassivHaus or one designed using PassivHaus principles, but the heating demand you've shown exceeds the PassivHaus standard of 15 kWh/(m²a). Still a great result by any measure.

Before saying you need xxkW, you need to look at the various performance tables of different heat pumps, as one 3 kW heat isn't he same as another, they give different rating to suit what they want to sell. Main issue isn't really the size anything up to about 6kW should be ok. Main issue will be have a design that doesn't require a buffer for the shoulder season, so engaged always open system water capacity is important, roughly 40L. That will allow the HP to run without short cycling and for defrost. If you can get your head around a single zone heating system, that where you need to heading, simple weather compensation your install can be very simple.

Will need a lot more information. Size of the house will help. Have a hunt around on here for Jeremy Harris' heat loss spreadsheet.

I would leave it. Ice on the casing will change the sound, if it’s working ok let it sort itself out

Is there any particular reason to specifically target "covering our own usage"? I get why it's a target conceptually, but it's actually pretty arbitrary - there's no logical reason to assume that this is the optimal target when you take costs into account. I assume you're going for batteries too. Have you modelled how changing battery and array capacity changes the numbers? Is it possible that a smaller array with more battery capacity allows better usage? Where are you going to put the array? 22 kW is physically huge. For comparison, we have 8.5 kW and this is what it looks like on the (flat) roof of our house. For reference, the house footprint is roughly 160 m2: I assume have three phase? If not, you'll struggle to get approval to connect an array that big to the grid. Apologies if you've already worked through all of these questions, but 22 kW is the largest domestic array I've ever heard of!

Oh I found it Section 18

Thanks for the data! Yep, this works out perfectly. Our average daily consumption is 22kWh (we have two electric cars, family of four). If we extrapolate your generation to our size array, we get: (171kWh * (22kWp/5.12kWp)) / 31 days == 23.7kWh

That is about half my usage, and if I had a heat pump, it would cover it all. Trouble is, I would have to cover my neighbours roofs in PV to supply just me. Should have jumped on the 'Roof for Rent' scheme and that 200 kWh would have earned me around £120.

Yes. Worst I saw was an old kitchen wall cabinet on a post with a bit of roofing felt tacked on the top and the DNO were happy.

22 kW

I'd be interested in knowing what the surveyor said when you bought the house given it's so recent a purchase so presumably those cracks have reappeared in quite a short time. Were they the same sort of size? And in the same sort of place? No obvious issues that might be contributing? big trees close to house? water washing away sandy soil over time? (Dodgy drain, leaky gutter??). Had a neighbour once who had a problem from massive Lleyandi, a good 10m from his property, but it was clay soil and they are thirsty trees But as above (non expert here) needs an SE view. Keep us updated?

Probably OSB trays with pipes laid in a pug ( biscuit ) mix screed @ProDave may have detailed this on his blog(?). If too intrusive, you could use aluminium spreader plates. The focus on detailing here needs to be about making the void 'warmer' and less drafty, so fully filling the width with PIR and foaming the gaps will be a good place to start. I fear this system is currently wasting a LOT of the available heat energy keeping these layers of wood warm, with little then left to rise upwards as space heating. The installer hasn't looked into this properly, and therefore hasn't mitigated against these associated ( accumulative ) losses when working out what's needed. You could go back to rads upstairs, but they'd need to be huge.

Just another data point for @SteamyTea's table. ATM, the external temp is 0.3°C and falling and our daily ripple is about 1.3°C and we only heat the house in the off-peak window (midnight - 7AM). The temp peak varies slightly across the various rooms but a typical value in this cold spell is at around 11AM and the minimum at around 2AM, so the house drops a little under 0.1°C/hr. When the average outside temp was 6°C, the daily ripple was just under 1°C.

What about using these?

Some of these inverters have a minimum load, wired in one that would shut down unless it was greater than 200W. Try a heavy load on it.

Alterations are allowable and covered in OFGEMs updated FIT rules https://www.ofgem.gov.uk/publications/feed-tariffs-fit-decision-replacement-generating-equipment

Thanks @MikeGrahamT21, interesting stuff. Our PV was commissioned at a similar time/rate. Until recently we've had no idea how much of what we generate is actually exported, but suspect it's less than 50%. We now have that ability so i'll watch with interest as the year progresses 👍🏼

It looks like at least part of your upper floor is above the garage? While heat going down from upstairs into a room below would not be "wasted" any such heat going downwards into the garage would be. Also with that portion of the upper floor above a garage, it is likely there will be air paths due to leaks etc allowing the cold air from the garage to the inter floor space. I suspect the solution lies with taking it all up again and doing it properly, making sure the entire ceiling above the garage is properly air tight sealed and properly insulated, then re fit the UFH. With carpet is is likely you will need the UFH pipes closer together than the downstairs UFH. Probably not what you want to hear.

Like a present on Christmas day. The novelty soon wears off.

Those houseplants trapped behind the curtains will create the condensation on the inside of that window.

if i may join in here....our house isn't finished yet and isn't airtight (we have 2 openings to the garage and the garage doors are sheets of OSB on hinges (i have a piece of PIR leaning against a wall between the house and those openings). we only have heating in the basement at the moment. yesterday at about 4pm i turned off the heating as it's dry down there now and it's just using electricity for no real reason. when i left the build it was 19.6°C in the basement and 14.8°C on the ground floor. overnight temps were -3°C. this morning when i went and checked (at about 10am), the basement was at 16.8°C and the ground floor at 12.2°C. i'm pretty happy with those loses for now considering we're not even airtight and it's fricking freezing outside (Mr. Bigglesworth). so it really makes me feel good that eventually we should have an efficient and warm house with minimal heating loses. when i finally get it finished that is!

Good to hear all resolved !!

Not from large suppliers that offer reliability and flexibility, but small domestic suppliers are probable a pain to them. As well as that, domestic suppliers are often trying thier hardest to not export. The idea of SEG, FiTs and previous schemes (ask @DamonHD what he has) was to help start an industry, not reward purchasers. The UK is currently trying some very complicated and difficult schemes (just look at what Octopus are doing) to understand. This is mainly because we are trying to shoehorn a distributed generation system onto a centralised generation system, and the easy way to do that is to cut usage, not increase generation.

I cant see electricity suppliers not wanting to buy excess renewable generation so I'd be surprised if SEG or a similar system wasnt in place for a good while. If youre making a decision to install kit based on receiving payments its probably prudent to also consider the same project without payments.

TBF - smoothing out usage reduces the need for backup infra.

Displaced, not saved.

I'm going to order it when available. Also a Tesla sex bot. Wonder how the two would get on?

On my site it would get promoted to site manager ! . I so want one !

That is the difference between us.