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Finding GPT really useful for this. It suggests: 2K water temp drop, combined flow rate 26.9 L/min 5K water temp drop, combined flow rate 10.2 L/min 10K water temp drop, combined flow rate 4.65 L/min I guessed at some of the heat loss specs but they are roughly inline with what I've seen while browsing radiators. So in summary, to ensure sufficient flow I need to balance to maybe a dT of 2-2.5C? (I doubt my boiler will ever fire at full modulation for long at all given the size of the radiators so maybe could target minimum flow and around 4K drop)?

Welcome @woodstream! Parts of my house are built into the roof like this. The 45 degree bits have badly fitted PIR insulation where the cold air goes both sides of it(!); we've decided the payoff from tearing down the ceilings to redo it isn't worth it, so I've focused on the vertical walls. If you need to crawl in the tight space, treat yourself to the recycled plastic bottle insulation, it's a lot more pleasant to work with. I put 100mm of this in the 1m high vertical wall on one side of our bathroom, and that alone raised the temperature by 2C in winter, so it's worth doing. Where you can get to the 45 degree rafters, pop mineral wool batts between them (remember it needs supporting, with netting, plasterboard, whatever - it will sag without) leaving a 50mm gap for ventilation. It can be easier to put wooden battens along the joist to enforce this gap. And then make it as airtight as possible, because draughts going round your insulation will undo much of the indoor comfort that your insulation brings. If you're up for it, put an air and moisture tight membrane on; otherwise plasterboard and seal all cracks carefully.

Looking to use the Polypipe bottle gully with concrete antisplash surround (UG425AST). It's not cheap (~£50) but finishes things quite neatly. I had intended to use the concrete hopper (UG414AST) which has a square grate, but that has a 110mm vertical outlet that I would have sent into a rest bend but for levels. I just need to decide how far to position it from the wall. Pulled away from the wall slightly would make access easier but leave a gap between the wall which would need dressing. If water blasted out of the downpipe it could in theory overshoot the concrete surround if it is too far back, but that feels pretty unlikely. Positioned with concrete surround touching the wall, shoe dipping below the top of the concrete: Positioned with concrete surround 25mm from the wall, bottom of shoe level with top of concrete: Positioned with concrete surround 63mm from the wall so that shoe is just over the grate, bottom of shoe level with top of concrete:

Best it can do is set the pump at 70%.

Looking at the installation manual it needs 21.5 Litres/Min at Max output pretty much in line with my ball park numbers. I'm guessing as the boiler has control of the pump it's not possible to slow the flow rate down and with 9 smallish rads it's going to have a narrow DT unless the boiler sees that and slows the pump down as well as modulating down to min.

Maybe I need to look more at tariffs. My assumption in the future is that export rates will reduce as more people get solar, because they'll all peak at the same time and at that time the generation will greatly exceed energy requirements. Other than being future proof, why look for a system which doesn't require internet? I imagine internet is only for some smart features, not for basic functionality? the one who offered 3 or 5 said the 5 would be a 'small additional cost' and the 8kW one didn't mention but I assume would get consent as part of the install. In the event we want to charge during the day (and if we have 2 EVs that might be more of a common occurrence), it would make sense to use stored energy in the battery wouldn't it? If I have a 3kW inverter and charge at 7kW I need to import 4kW from the grid at peak rates. Sorry if I've misunderstood. Not sure I agree - charge at 7-8p/kWh, get ~3miles/kWh efficiency means ~2-3p/mile plus 3p new tax still makes it probably half the price per mile of a petrol or diesel. Things will change though over time. Personally I hope someone manages to reform the UK energy market to enable cheaper electricity from renewable sources.

2x Single Flat Panel 800x500 2x Single Flat Panel 1000x600 1x Single Flat Panel 800x600 1x Double Flat Panel 800x600 1x Single Flat Panel 400x500 2x Towel Rail 500x750 Total 9 All fed via what looks like Speedfit 15mm pipes homerun to manifolds at the boiler. 22mm copper at boiler. Edit additional info: Pipe is through the floor (presume embedded in screed, though can't feel heat through floor except in very limited area near manifolds. Furthest radiator is about 6m straight line away, closest <2m

Do that for all the rads and then sum up the total flow rate and you'll have a better idea of the total flow rate. Rule of thumb I've used over the years is for every kW of boiler output (up to 15kW) you need a min of 1 litre/min for each kW to keep the boiler happy (this is probably out of date for modern boilers with good turndown ratio's.) After 15 kW provided the boiler modulates down you can get away with an extra 1 litre/min for every 2 additional kW increase Example - current boiler is 16kW but range rated down to min - most it hits on start up is 58% of max output so 60% of 16 is 9.6 kW Current Flow rate is 0.6 m3/hr = 10 litres / min is more than enough to keep the boiler happy under start up conditions and in normal running Manual Says 633 Litres per hour is the expectation which is 10.5 litres/min

I was at university in 1981, not much in the way of politics, though on my course most students were basically right of centre. Went again in 2005 and again, not much interest, though most students were left of centre. I think the centre has moved to the right. Prior to 1981 I did my apprenticeship, most people I worked with were very central in their politics. I think there was a bigger gap between Labour and Tory during the 80s, but that was mainly because Thatcher and Kinnock were miles apart, and we all saw how well that helped the Labour party.

I went to uni in 1969, was involved in student politics, i.e. the student's union. Apart from some big 'events/demos' I don't think students were particularly involved in Politics, the 'clubs' aligned to the major parties only had a few members. Compare that with the numbers a while back marching for Gaza, climate change etc. And don't forget, back then less than 10% went to university. Thanks to Blair, almost 50% go. And don't get me started about the lack of vocational training as a result.

Id over specked my radiators as I've a mixture of those fashionable tall radiators that are a bit rubbish and modern radiators that cool down quickly. My old control unit didn't have a universal back plate. I got it all wired in this morning. I spent ages looking at all the wiring diagrams and instructions prior to starting and got myself all confused, then I actually looked at it and figured it out instantly. Now i just need to dial in some killer settings so i can save tonnes of money 🤣

So how many radiators do you have

Two reasons: 1. It wasn't installed as one and I don't have the kit it was supplied with (manual says it should have been included in the box) 2. While I'm sure I could get the kit, the boiler is installed in the centre of the property and installing an outside sensor would involve making lots of holes in plasterboard. As I needed to replace the timer anyway, my plan was to use load compensation instead of weather compensation. It might not be as good but it's a lot easier to set up. Neither is going to be particularly useful with the size of radiators I have in the room with the highest heat loss and the overall ability of the installed radiators to dissapate the boiler output at minimum modulation (6kw) Overall I think so (just wrote a lot on this) but then realise that I think you are just referring to this specific bit: Firstly, there is a bypass installed. I have two towel radiators with manual flow valves only (not lockshields, so nothing to prevent anyone adjusting them). It's not entirely clear to me what they mean by uninterrupted flow. I've adjusted the valves so there is a dT across these two radiators of about 5C. One of these radiators is the closest to the boiler (<2m) so was bypassing a large portion of the flow until I started balancing. 10% of the minimum output of my boiler is 600W. The radiators are 500x750 and looking at similar online they I'm finding outputs specified as ~250W per at dT 50. I struggle to believe that's right given the heat output I get from these (the one closest to the boiler seems to overwhelm the other radiators nearby (assuming doors are left open) putting out enough heat that the other radiators barely come on. Even if these two towel radiators are turned down too much right now, there will still be plenty of flow elsewhere to satisfy the minimum specified above as I have the TRVs removed from 4 radiators with a total output (at dT 50) of approx 3500W, these rads were (at the start of this thread) controlled to a dT of about 8 but all still putting out decent heat.

Or more complete cut and paste is Kilogram Definition: A kilogram (symbol: kg) is the base unit of mass in the International System of Units (SI). It is currently defined based on the fixed numerical value of the Planck constant, h, which is equal to 6.62607015 × 10-34 in the units of J·s, or kg·m2·s-1. The meter and the second are defined in terms of c, the speed of light, and cesium frequency, ΔνCs. Even though the definition of the kilogram was changed in 2019, the actual size of the unit remained the same. The changes were intended to improve the definitions of SI base units, not to actually change how the units are used throughout the world. History/origin: The name kilogram was derived from the French "kilogramme," which in turn came from adding Greek terminology meaning "a thousand," before the Late Latin term "gramma" meaning "a small weight." Unlike the other SI base units, the kilogram is the only SI base unit with an SI prefix. SI is a system based on the meter-kilogram-second system of units rather than a centimeter-gram-second system. This is at least in part due to the inconsistencies and lack of coherence that can arise through use of centimeter-gram-second systems, such as those between the systems of electrostatic and electromagnetic units. The kilogram was originally defined as the mass of one liter of water at its freezing point in 1794, but was eventually re-defined, since measuring the mass of a volume of water was imprecise and cumbersome. A new definition of the kilogram was introduced in 2019 based on Planck's constant and changes to the definition of the second. Prior to the current definition, the kilogram was defined as being equal to the mass of a physical prototype, a cylinder made of a platinum-iridium alloy, which was an imperfect measure. This is evidenced by the fact that the mass of the original prototype for the kilogram now weighs 50 micrograms less than other copies of the standard kilogram. Current use: As a base unit of SI, the kilogram is used globally in nearly all fields and applications, with the exception of countries like the United States, where the kilogram is used in many areas, at least to some extent (such as science, industry, government, and the military) but typically not in everyday applications. Pound Definition: A pound (symbol: lb) is a unit of mass used in the imperial and US customary systems of measurement. The international avoirdupois pound (the common pound used today) is defined as exactly 0.45359237 kilograms. The avoirdupois pound is equivalent to 16 avoirdupois ounces. History/origin: The pound descended from the Roman libra, and numerous different definitions of the pound were used throughout history prior to the international avoirdupois pound that is widely used today. The avoirdupois system is a system that was commonly used in the 13th century. It was updated to its current form in 1959. It is a system that was based on a physical standardized pound that used a prototype weight. This prototype weight could be divided into 16 ounces, a number that had three even divisors (8, 4, 2). This convenience could be the reason that the system was more popular than other systems of the time that used 10, 12, or 15 subdivisions. Current use: The pound as a unit of weight is widely used in the United States, often for measuring body weight. Many versions of the pound existed in the past in the United Kingdom (UK), and although the UK largely uses the International System of Units, pounds are still used within certain contexts, such as labelling of packaged foods (by law the metric values must also be displayed). The UK also often uses both pounds and stones when describing body weight, where a stone is comprised of 14 pounds. Kilogram to Pound Conversion Table Kilogram [kg] Pound [lbs] 1 kg is equal to 2.2046226218 lbs

So how far back would you go to get to the 'good times'? I presume you mean Brown? I wonder how differently things might have gone if he'd been able to see through his plan to get out of the 2008 crash. Cut VAT, encourage consumer spending, grow your way out. Instead we got the coalition who tried to cut their way out, and we've had stagnation of wages and living standards ever since. That's almost my entire post-student life. I don't honestly know if Brown's economics would have worked any better. But other countries certainly bounced back faster. I returned to uni in 2012 as a mature student, and I was pretty appalled by how little interest the younger students had in pretty much any sort of world affairs. That's not to say they were following the Kardashians et al, but they just wanted to do their own thing. Nobody joined any sort of political organisations, went on rallies, etc. The idea that students are where new political movements are cultivated is no longer true. They don't actually want to change the world, probably because they don't believe that they can. It's very sad. These are supposed to be our brightest cohort who will move in to positions of influence in society.

Not exact though. I think the distance measurement is the only one that is a stated conversion rather than a defined one based on something real i.e. wavelength of light.

Strange until I joined the RAF (1986) I did the same, now its always metric so kg, and metres. Yes and 2.2 lb to the kg

Good idea! This is what GPT came up with (which seems good to my non-mathsy eyes): Flow rate for the specified radiator and temperatures Given your inputs, we can estimate the radiator’s actual heat output at 60°C/50°C water and 21°C room air, then use an energy balance to get the flow rate. Given data Radiator rating: 550 W at ΔT50 (mean water to air) Inlet water: 60°C Outlet water: 50°C Room air: 21°C Radiator output at actual conditions Mean water temperature: Tm = 60+502 = 55∘C Temperature difference to air: ΔTair = 55−21 = 34∘C Output correction (ΔT method): Radiator output scales approximately as Q=Q50(ΔTair/50)^n. For typical steel panel radiators, n≈1.3. Q ≈ 550×(3450)^1.3 ≈ 550×0.606 ≈ 333 W Flow rate calculation Water-side temperature drop: ΔTwater = 60−50 = 10∘C Mass flow (energy balance): m˙ = Qcp⋅ΔTwater ≈ 333 W / (4180 J/(kg\cdotK)⋅10 K) ≈ 0.0080 kg/s Volumetric flow (water, ρ≈1000 kg/m3): V˙ ≈ 0.00801000 m3/s = 8.0×10−6 m3/s ≈ 0.48 L/min ≈ 28.7 L/h Notes and sensitivity Exponent sensitivity: If the radiator type uses a different exponent (e.g., n= 1.2 to 1.51.5), the output—and thus flow—varies modestly. Across n = 1.2–1.51.5, the flow would be roughly 0.44–0.53 L/min. Fluid properties: If you’re using glycol mix, adjust cp and ρ\rho accordingly; glycol will increase the required mass flow slightly. Direct answer: About 0.48 L/min (≈29 L/h) for water under these conditions. If you know the exact radiator type, I can refine the exponent and give a tighter figure.

I started my apprenticeship the year Mrs T came to power. I can remember the labour governments before that, and the winter of discontent, rolling power cuts, 3 day week etc. so things were not good before then. I know it is trendy now to blame her for everything, but she did do some things right, though a lot of things wrong. It almost sticks in my throat to say it, but the early Blair years seemed good (apart from that war) but things went downhill when it was Blairs turn in the hot seat and has not really improved since. My daughter has no interest in politics, never watches the news, doesn't read a paper. She just gets on with it and takes whatever is thrown at her and lives her life doing the best for her, as I have said before she makes decisions for her usually not thanks to government policy but regardless of it. I suspect a lot of younger people take that attitude, so it's no wonder the old stick in the mud folk are the ones that still vote and still complain.

1" is 25.4mm exactly.

That would make sense. I suggested this years ago as a cheap way to reinforce the local grid.

Similar here, though pretty sure imperial measures was touched on, though I couldn't convert metric/imperial in my head until much more recently. Whatever happened in school I think I've ended up using Imperial more as I got older* though not for anything important. I've always measured my height and weight in imperial but if I'm measuring or weighing anything else it will be in metric. * In recent years I've been watching a lot of makers on Youtube and a lot of them are American and so I've been a lot more exposed to Imperial measurements than I was when I was younger.

At these low battery storage prices I wonder how long before someone like octopus will install a battery system at your house for free, you pay an elevated standing charge but get upto 15kwh a day "included" then a higher unit price afterwards. The battery charges up under control of energy firm at various times when the wholesale price is really low. Say the kit (battery plus 10kw inverter) costs energy Co £5k installed and is 15kwh usable. We assume the kit will last 10 years. So. Energy Co. Need £500 a year capital, let's say £730 or about £2 a day. The usual price for 15kwh at 25p plus 50p.standing charge is £4.25 If the energy. Co offered £3.75 a day, they would have 1.75 to buy 15kwh of energy, abiut 11.5p a unit average over the year. I reckon thry could do that. They can already seem to afford to give EV owners 8p a unit.

Keep it simple and use something like this? https://www.tlc-direct.co.uk/Products/SMTGBD4.html * Confirm with electricitian this is suitable

Yes, those ribbed sections are 1cm apart, so you can cut it to length. I ended up doing this all over, with good results! I even used one of the off-cuts to extend another section where I needed a longer section, joined with a regular metal-with-rubber-rings piece, as the 125mm plastic pieces fit together perfectly with the 125mm spiral ducting pieces.