Hot water cylinder recovery

That depends on the size of the cylinder and the bath. Modern average bath is approx 100 litres. 2/3 to 3/4 is added cold water. So if an 80 litre Part L, it will be 1/2 hour. An 80 litre quick recovery will be 15 minutes, provided the boiler is man enough.

????

My God and your are supposed to a pro. A quick recovery cylinder reduces gas consumed.

Reply to
IMM
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Balls to the lot of you. O level maths introduces you to calculus. This used to be A level only, and before that degree level.

Reply to
IMM

In message , IMM writes

In my day it was "O" level

Reply to
raden

Maxie, you are very old and spherical and Calculus wasn't invented then. Behave!

Reply to
IMM

In message , IMM writes

How would you know ?

Reply to
raden

You told us all.

Reply to
IMM

I did calculus in third form at grammar school......

.andy

To email, substitute .nospam with .gl

Reply to
Andy Hall

So did I , but my grandfather was introduced to calculus in the second year of his undergraduate course at the University of London.

Reply to
Neil Jones

Exactly. It was a degree subject that has dropped to O levels.

Reply to
IMM

I did all the specific heat stuff at gcse 12 years ago, but never did any calculus - I wasnt introduced to calculus until part way though my HNC.

Reply to
a

Me too. Differentiation in the third form and integration in the 4th, probably, leading I think to areas under simple polynomial curves and volumes of revolution.

There were _definitely_ calculus questions in the JMB O-level I took in

1968. I still have the question paper somewhere - I'll dig it out and post some of the questions if anyone doesn't believe me.

And on the BBC TV news the other night we saw a boy jubilant that "I've done really good" - apart from the English, presumably. Aaaargh. I would _like_ to believe those who say standards haven't fallen, but _just_find_ it impossible to do so.

Reply to
Andy Wade

I think you mean *had* dropped to O level. I have just had a look through the GCSE syllabus from Edexcel and AQA and calculus is not mentioned.

Neil

Reply to
Neil Jones

Andy's memory is failing.

Reply to
IMM

I used to be, well just the into. I always though there enough in O levels anyway with having an into to calculus. It should be firmly in A level.

Reply to
IMM

Things were always better years weren't they, and you were always brighter than the current kids too. The same old boring groan........ The fact is the 1970s was full of graffiti and vandalism, many reading here would have been a part of that.

Reply to
IMM

In uk.d-i-y, Andy Wade wrote:

I believe you, Andy ;-) though my JMB O-level was 7 years later; I wouldn't swear to whether simple differentiation and integration were on the O-level syllabub at that time, as I kept up with Maths through A-level and one year's undergrad course - and it wasn't until the undergrad year that I felt I had "properly" understood calculus, wot with doing Riemann integration and following Michael Spivak's *beautiful* text (and learning to both incant and *apply* "for every epsilon greater than nought, there exists a delta greater than nought such that abs( f(x +- delta)

- f(x)) is less than epsilon" (shamelessly misquoting and glossing over the highly relevant point that f(x) may not be defined for x at the Interesting value, and dropping all mention of the Limit value... but You Know What I Mean ;-)

The specific-heat thing, OTOH, was most definitely O-level, since I dropped physics after O-level (as there was a one-in-three chance of getting the useless prat who ran the physics dept as the teacher for two years of what should've been intellectual challenge...)

I peeked into the normally-suppressed IMM contributions to this thread, and noticed he'd described my "step by step" exposition of how to get from 4.2kJ-for-1L-thru-1-degree to "about half an hour for a 150L tank and a 20kW boiler" as "terribly(?) complicated", instead showing an "all in one" formula. Sigh: remembering one, or rather fifty-seven assorted, formula(e) is precisely *not* "education" in any meaningful way - it's being able to do the back-of-the-envelope-from-general-principles stuff (with appropriate rounding and choice of easy numbers to work with, rather than "can't do it without a calculator", too!) which gives you the generality of understanding, and allows the same basic knowledge to be applied to "how fast will my HW cylinder warm up", "why does the immersion heater take S-o-o-o L-o-o-n-g to warm up my tank", "how long should this kettle take to boil", and "what flow rate can I expect from this combi/electric-shower in summer and in winter?", and all the rest. No surprise there, I suppose... nor any mention of the principle by which a "quick recovery" coil manages to, apparently, halve the heating-up time of a tank of hot water! Presumably, "quick recovery" is trade-speak for "has a more efficient heat exchange system", like maybe more turns in the coil or a plate heat-exchanger, which means a greater temperature fall across the boiler's flow-and-return connections and/or allows for a boiler with a bigger heat output to be hefted into use. But in our resident brocure-reader's world, it's All Just Magick; Arfer See Clarc applies!

Well, there we're into the distinction between informal speech idiom, and standard written English: wot passes for quite OK when said in a moment of elation in an informal context - and, let's remember, selected for broadcast by an editor looking for a story - isn't what anyone with sense and edjerkayshun wants to see written down in an exam paper, a business letter, or a magazine article. I've no problem with kids being explicitly aware of different registers of language; I do have a problem with wishy-washy teachers who can't be arsed to teach kids the *appropriate* register to Move On In Life. You may be able to set up an environment within a local school where particular idioms are acceptable/widespread not only in casual speech but in written work: but you're doing those kids a considerable disservice if you let them go right through their school years thinking their job applications, Usenet postings, letters-to-the-Council, and all the rest will be treated just as seriously as others if they're full of misspellings, malapropisms, non-standard idioms, and so on.

Stefek

Reply to
stefek.zaba

Speak for yourself, buster.

.andy

To email, substitute .nospam with .gl

Reply to
Andy Hall

I can understand why you would think that........

Your real name wouldn't be Charles Clarke would it?

.andy

To email, substitute .nospam with .gl

Reply to
Andy Hall

in

It is clear you vandalised, the clear guilt is there.

Reply to
IMM

Why?

No. Nice man though.

Reply to
IMM

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