jack

That's hardly the same thing. Used lithium is still fundamentally lithium. Used nuclear waste is an entirely different set of atoms.

That's the current situation - as you say, it's a finite resource, which means it will ultimately become more difficult and expensive to extract. The rising price will push research into recycling, so that will become cheaper and more efficient. Of course, by then, we may have other storage possibilities that reduce the demand for lithium batteries.

I'm sure it could be done more cheaply with a Willis heater, but for not that much more money I agree that having everything in one integrated and warrantied unit is attractive.

A Willis heater is an inline system, no tank required. You could use a small tank as a buffer if you wanted to. You'd need to check with a plumber as to whether an expansion tank is required given the volume of the system.

An ASHP is much, much cheaper than ground source. For what you're trying to achieve, you'd be buying the smallest possible unit. You can probably get something for £1700-2000, depending on brand (you might get it cheaper if you're willing to go the ebay route). Installation isn't too hard, and with an installation this size you can probably avoid a manifold + pump (etc) and have the ASHP drive the UFH directly. I do worry that even the smallest ASHP will be so oversized that it will be cycling on and off a lot. Edited to add: ASHPs are fugly, for sure, but usually you can tuck them out of sight. The issue you'll have with your situation is that you can't put it at the back or side of the building, because there's no space. You could put it at the front, but you'll need some form of screen to camouflage it. I wouldn't worry too much about noise: if you're using it, the doors/windows will be closed, and decent inverter-driven ASHPs really don't make very much noise, especially when they aren't being driven very hard (as would be the case with your setup). Given how low your heating requirement will be, I'd really think hard about whether it makes financial sense to go for such an expensive heating option for a space like this. Alternative idea: @TerryE plans to use an ASHP with UFH, but is presently experimenting with a Willis heater to get a feel for how much heating he actually needs. A Willis heater is basically a standard immersion heater in a sleeve, which heats water as it's pumped past. It's incredibly cheap and simple - eg, here's one for less than £50. You'd need to add an UFH pump to this, but it's still a lot cheaper than an ASHP. They're very reliable, and if it breaks you can buy a replacement immersion heater off the shelf for peanuts. In comparison, we had a pump go on our ASHP after less than three years and that cost several hundred quid to replace (had to replace a circuit board and pump together). In your situation, I'd consider a Willis heater driving a radiator or underfloor heating, and wiring up (but not yet fitting) provision for an air conditioning unit that can be retrofitted if you find it regularly getting too hot in summer. You could spend the money you were going to spend on an ASHP on better insulation (as mentioned above, timber frame is definitely your friend given the space constraints), which will further lower your energy requirements. Pay attention to shading so that you maximise gain in winter and reduce it in summer.

Our plumber nearly choked when I told him we were considering a 5-6kW unit for our 290m2 house. He wanted to install a 15kW ASHP as a minimum. His main concern was how cold the house would get during the 1-2 hours that the ASHP would be heating the cylinder early in the morning. In reality, it takes something like 24 hours for the house temperature to drop by any significant amount!

Absolute worst case, some form of resistance heater can always be employed to supplement the ASHP output on the very coldest days of the year. For example, judicious use of a fan heater would be a low capital way of topping up any shortfall. By way of example, we got by through all of last winter with a 1.5kW column heater in our kitchen after our ASHP packed up. I should add that this was the only proper heat source we used to bring the house up to nearly 20 deg C from the 14.5 deg C it reached while we were away for three weeks over Christmas 2017. Sure, I would have preferred parts of the house to be warmer at times, but it wasn't the end of the world.

We have the same. Wouldn't be without them, although I don't bother with the solar tracking function. As for light, I don't generally close ours fully. You only need to stop the direct light, which is nearly always achieved with the blinds partly closed. Enough reflected light still gets through to light the room. Nothing keeps the heat out better than external barriers in my opinion. Our bedroom faces east, and unfortunately it's the one place we should have specced blinds but didn't. We have thermal fabric up but it gets hot and radiates into the room. I wouldn't rely on it as a way of keeping a room cool if it gets direct sun.

That was me on the weekend (minus Faye). Great weather to be up in the mountains having a cold one.

Find me a better selfbuild forum on the web. I'll wait...

That's a child, not a "blending thing" you nutter! It's an odd thing to have on a cylinder though, I agree.

I hope you don't mind me being honest, but I think it's getting worse rather than better. This looks like three or four houses chopped up and put back together One thing that this revision emphasises is the fact that on the right, the upper storey overhangs, but on the left it's set back. Then the front bit is completely different in style but partly merges in due to the roofline. At the moment, there are random planes at all sorts of depths in the front elevation. Try to think of the design in terms of intersecting volumes - that might help resolve things.

Yes, but it still has the problem of one roof merging into another: I think it looks strange, especially with the lack of symmetry as mentioned by @ultramods I think you may also struggle making it look as neat as this in real life. For example, how will you blend ridge tiles into the merged portion? I think it'd look better if the roof over the atrium were clearly higher or lower than the roof it presently merges with. It's achieving that without fussy joints that may be a challenge, and that's why a flat roof could potentially be a solution. If it's south facing, you really want to be thinking about solar gain control. Fixed or moveable slats might be an option. External would be best from a functionality point of view, but will likely be more expensive and visually intrusive.

Beat me to it, I agree. I do like the way the double-height bit in the middle comes out from the rest of the house, but it doesn't (to my eye) work where its roofline meets the roof to the right. You could also consider whether having a dual pitched roof over the atrium might work - could be a bit fussy getting it to sit with the rest of the roof though. To my eye, the windows under the dormer look like they're too far to the right. It think they might look better moved to the left to leave some space between them and the double-height section. Not sure how that works with the dormer above. I like the mix of materials, although I'm not sure about the cladding to the bottom left. To me, cladding feels lightweight, and shouldn't sit underneath heavier-looking construction. I'm not a huge fan of the wide roof over the dormer on the left. I see why you've done it in terms of pitch-matching, but it draws more attention to itself than I think is ideal. Overall though, it's a great start - fantastic improvement over what you're starting with. Oh, and before you go too far, have you considered solar gain given how many windows are being introduced to this elevation?

Bet you a million quid he "unbuilt" a hell of a lot more than he built for £600. I don't care how angry he was or how unreasonably he was treated, what he chose to do was stupid and reckless.

Ah, same as ours then (I seem to recall reading once that the heat exchanger is common across a lot of these units). I did give it the once over, but I suspect it could do with a more aggressive clean at some point.

Would you want to be a customer of his though? What an absolute waste over £600. He hasn't hurt the people who actually owe him the money, and now risks a criminal record (assuming he hasn't got one already) and the cost of repairing the damage.

Whatever you use, it needs to be closed cell.

I remember reading about that or something similar. It's absolutely critical that these things are maintained. I was surprised to find that the heat exchanger on our Brink unit is riveted to together, so can't be taken apart for cleaning. I'm sure I remember reading about at least one person (@Bitpipe maybe) who was able to take theirs apart and wash all the individual plates. I may look into whether it's possible to do this by drilling out the rivets and replacing them with some other form of fastener.

We had a leak from underneath our MVHR unit a few days ago. I took apart the u-bend underneath and was horrified to find it 95% clogged with some sort of bio-jelly. The leak was caused by water backing up above this in the cold weather (lots of condensation) and then finding its way out around where the threaded outlet is connected to the unit (loose screw, now tightened). I cleared the u-bend out then decided to check the rest of the internals. For context, until about a year ago I checked the inside of the MVHR unit pretty regularly - virtually every time I changed the filters (so maybe once every three months on average). It was always spotless. I then got a bit slack and probably haven't checked it since last winter. This time, however, it was pretty disgusting. There was a patch on the heat exchanger where some mould was starting to build up. There was also some pretty disgusting biological buildup on the drainage surface under the heat exchanger and around the drain. Worryingly, there was also a pool of standing water underneath the filter for the incoming cold air. There's a pocket there that doesn't drain but could potentially hold quite a lot of water before it would start overflowing into the drain. I cleaned it all out and sprayed it with bleach. I'll be keeping a much closer eye on this in the future, but I thought I'd share this with others as a warning.

We have a Quooker (same model, I think) and were advised to use unsoftened water. We're in a moderately hard area I believe. Descaling is actually a really simple process. The scale doesn't build up on the element - it just falls off in little flakes and sits in the bottom of the unit. If you have any diy skills at all, it's a simple matter to take the lid off, tip out the water with the scale, and put it back together (you must use a new seal, which I think they provide at least once for free if you ask them). We had a problem with ours about two years after installation. I can't fault the quality of Quooker's after-sales service - the engineer was here for 90 mins diagnosing and then fixing the problem.

It's on the (very, very long) list of things to do. The list I should be working through right now rather than posting on BH. Unfortunately, we do have some shading from a large tree to the west south west of our house. Microinverters help, but when there's shade, there's shade.

You're making me feel inadequate now!

An interesting thing about PV, especially if you're using a standard inverter rather than micro-inverters or similar, is that the worst-performing panel limits the power that can be generated by all the rest on the same string. That means that if even one panel is shaded or dirty, it drags down the amount the rest of the panels can generate, often by a surprising amount. Even shading a couple of cells on a panel can be enough to make a difference: [Edited to add:] https://blog.aurorasolar.com/shading-losses-for-pv-systems-and-techniques-to-mitigate-them/. Cleaning may therefore be worth it, especially if you have any panels that have algae or dust on them (even if only in a corner or along the bottom).

Wowsers, we only managed 11.9kWh and we have 8.5kW! Shows you what a difference angle and orientation makes on a sunny winter's day. We're stuck with a relatively flat array, much of which is east west. I also need to get up on the roof and clean mine!