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Next job is to understand how to wire this into the system As a temporary upper limit safety measure I'm using the original tank stat as a pipestat on the coil return it's not resting there it's got a spring wire underneath to hold it on 🙂

Many thanks for the pics @Nickfromwales

this exactly what I did when Mrs Alien used all her strength to jam it down - once out the sink stayed without a plug for months It doesn't help when she uses bleach every week down plug holes - eventually I replaced it with a swivel type (o ring seal) that also got bleached and the o ring swelled up so now doesn't close nicely - bloody woman thinks the solution to every cleaning is bleach - half my house maintenance tasks are replacing stuff ruined by bleach!!!!

Grant documentation says 1.61 kWh over 24hrs and energy lost at a rate of 67 W

Was having a conversation with a mate on whatsapp and he decided to put part of the comments above into AI Yes — those numbers suggest the new cylinder is substantially better, not just marginally better. The nice thing is that his temperature-decay measurements let us put sensible numbers on it. For a hot-water cylinder, a first approximation is \[ Q = m c_p \Delta T \]with water \(c_p \approx 4.186\text{ kJ/kg·K}\). So, for every 100 litres of water, a cooling rate of 1 °C/hour corresponds to about: \[ \frac{100\times4.186}{3.6}=116.3\text{ W} \]Therefore, at his measured rates: Cooling rate Heat loss per 100 L 200 L cylinder equivalent 0.60 °C/h 69.8 W 140 W 0.50 °C/h 58.1 W 116 W 0.40 °C/h 46.5 W 93 W 0.19 °C/h 22.1 W 44 W So if, for example, these were roughly 200 L cylinders, he's effectively gone from somewhere around 90–140 W of standing heat loss to around 44 W at that part of the temperature range. That's roughly a 60–65% reduction in heat loss, based simply on the measured cooling rate: \[ 1-\frac{0.19}{0.50}\approx62\% \]And it may be nearer 68% if the old cylinder was normally doing 0.6 °C/h. There is another interesting way of looking at his actual example. If the old tank went from 50 → 40 °C in 20 h, a 200 L tank lost approximately: \[ 200\times4.186\times10 = 8372\text{ kJ} \]or: \[ \approx2.33\text{ kWh} \]So that's about 2.3 kWh of stored hot-water energy disappearing every 20 hours. With the new tank at 0.19 °C/h, after 24 h: \[ 50-(24\times0.19)=45.44^\circ C \]A 200 L tank has then lost: \[ 200\times4.186\times4.56 \]≈ 1.06 kWh. So you're comparing roughly: old: ~2.3 kWh lost in 20 h versus new: ~1.1 kWh lost in 24 h That's a pretty striking difference. There's one subtlety, though. Heat loss isn't actually constant in °C/hour. It's approximately proportional to the temperature difference between the cylinder and the room: \[ \dot Q = UA(T_{tank}-T_{room}) \]so the temperature ought to decay exponentially rather than in a perfectly straight line. At 50 °C in a 20 °C room, there's a 30 °C temperature difference; at 40 °C there's only 20 °C. Consequently the old cylinder losing 0.5–0.6 °C/h near 50 °C is actually worse thermally than that simple 20-hour average makes it look. The London loops are relevant too. They're intended to reduce thermosyphon circulation along hot-water pipes — hot water rising out of the cylinder pipework, cooling, and creating a slow natural circulation loop. But if the new cylinder manages 0.19 °C/h even before the associated pipework has been fully insulated, that's particularly impressive. It suggests most of the improvement is inherent to the cylinder itself: better factory insulation, fewer thermal bridges, improved penetrations/fittings, etc., rather than just clever pipework. I'd be quite interested to see what happens after he lags all the new pipework. If he got down to, say, 0.15 °C/h, a 200 L cylinder would be losing only about 35 W at that operating point. So I'd reply to him something along the lines of: your new hobby may be slightly obsessive, but unfortunately your measurements say it's working — you've apparently cut the standing heat loss by something like two-thirds. 😄 If you know the actual cylinder volume, I can calculate the losses in watts, kWh/day and £/year quite accurately from his figures. the bit in bold made us both laugh

Here is the other side of the story about our electrical energy. https://www.bbc.co.uk/sounds/play/m0031h8j It is by Jonathan Ford, so be warned, it is not exactly unbiased.

If you can turn the push down plug bit it can be unscrewed to change the push bit. A suction cup might pull it up if it's strong enough?

Pessemistic, but realistic, and what is actually happening and will continue to happen.

Buy a 3D printer and print a spanner!

Yeah clicker one. Took the waste off but couldn’t get to it, argh!

Easier and quicker to go and buy a new pop up waste and fit it, 15 minute job.

I think if you unscrew the white waste pipe - which you should be able to do by hand - you may be able to get to the waste from underneath. Failing that, you may need to replace the waste. Is it a clicker one?

Once I’ve got that loose, should the whole mechanism come out fairly easily?

https://www.screwfix.com/p/magnusson-water-pump-pliers-10-254mm-/1791v

Can’t seem to get the mechanism out. Haven’t got a spanner big enough to loosen the black bit - any ideas?

Or just unscrew the whole metal piece and replace with new assembly - you seem to find spares for this stuff

Yeah I assumed that, take it off and just push it all up?

Go from underneath take the u bend off to get access.

The kids, but being 4 and 2 I can blame them but not much they can do 😂

Is there anyone around that you can blame?

He he he, no reason not to have some big Mitutoyo verniers on-site so you can ‘measure’ mm to 2 dp / 10 microns 🤣.

Plug broken so doesn’t work properly but unfortunately it’s been pushed down a bit too far, absolutely no idea how to get it out - any ideas appreciated! thanks

New Tank Fitted over the weekend Grant Tank - 180L 2.7m2 coil surface area couple of errors in pipework configuration that are resulting in increased heat loss but I'll fix them over the next couple of weeks. meantime a quick experiment on boiler efficiency (compared to old tank data) revealed Boiler efficiency Old tank when heating HW - efficiency was 88.97% (condensate volume 157 grams - condensate stopped after 10 mins of a 30 min cycle due to return temp being above 54 deg) New tank when heating HW - efficiency is 93.29% (Condensate volume 332 grams was generating condensate all the way thro the 45 min cycle) Can show workings if required....... Heat Loss Old Hot water tank fully lagged pipework - london loops everywhere (U loops on any hot outlets from tank) best I could get in term of temp decay in the tank was 0.4 deg per hour (most of the time it was 0.5 to 0.6 deg per hour) so heat a tank to 50 deg and 20 hours later it would be down to 40 deg (thats a just bearable shower according to SWMBO) New Tank - no lagging on pipework yet and minimal london loops and the tank losses are down to 0.19 deg per hour - so heat a tank to 50 deg and 24 hours later it's still over 45 deg - I think I need a better hobby!!!! PS Yes I need to fit a tank stat PPS The tank is set up as a vented tank (so no G3 certification is required)

Zinsser fixed a problem we had with peeling paint over a shower. Wouldnt use anything else now.

Haha, as with odd socks, there is somebody somewhere that must have a few million tape measures by now.