On 16/06/2020 22:25:34, wrote:
On Tuesday, 16 June 2020 20:08:04 UTC+1, Fredxx wrote:
On 16/06/2020 17:59:37, tabbypurr wrote:
On Tuesday, 16 June 2020 17:51:25 UTC+1, Robin wrote:
On 16/06/2020 17:41, tabbypurr wrote:
On Tuesday, 16 June 2020 09:28:35 UTC+1, Robin wrote:
On 16/06/2020 08:55, PeterC wrote:
On Mon, 15 Jun 2020 22:30:39 +0100, Robin wrote:
On 15/06/2020 21:55, tabbypurr wrote:


A rad is 100% efficient because there is nowhere for any waste energy to go. Thus energy input & energy output are actually the same thing for a rad.


That's conservation of energy.

Efficiency involves the concept of usefulness - as in the traditional
definition "the ratio of the useful work performed by a machine to the
total energy expended". On that it's entirely reasonable to consider
how a radiator in a CH system affects the ratio of the energy released
where it's wanted to the total energy expended (i.e. including all the
energy released where it's not - e.g. in the boiler, pump, and pipes
under suspended floors).

Looking at it another way, I'd consider a radiator which took water in
at 70 degrees and passed it out at 65 degrees to be less efficient than
one which passes it out at 55 degrees. The second done is doing a much
better job at putting the energy where it's wanted.

Is that efficiency or is it effectivness?


It's a fair cop that I conflated the 2. My mitigation is that I was
trying to stop the post growing even longer. Slightly longer 2nd attempt:

The second radiator is more effective (assuming it's a good thing to
have at least the option of warming the room faster)

probably, though I don't know what 'second one' you refer to

and (very probably)
also more efficient

no.

in that the CH system delivers heat to the room more
efficiently.

no. You are still not grasping what radiator efficiency is.


Please state your definition.

NT: useful energy out over energy in is the definition.

With a wet radiator there are only 2 places energy can go: into the room or out the outlet pipe. In neither case does the rad lose any energy, hence efficiency is 100%.

Energy efficiency is always going to be 100% for a radiator.

Efficiency has several meanings. This might assist:
https://en.wikipedia.org/wiki/Effici...disambiguation)

only one of which applies here, and that is:
Energy efficiency (physics), the ratio of power consumed to useful power output


For the avoidance of difficulty in comprehending English, this may also
assist:
https://www.oxfordlearnersdictionari...lish/efficient

Adjective: doing something in a good, careful and complete way with no
waste of time, money or energy

a usage of the word that applies primarily to a person's actions. 'with no waste of energy' certainly applies to radiators. Good & careful certainly have nothing to do with radiator efficiency.


It doesn't just have to be time, money or energy. It could be weight or
area in respect of a radiator.

sorry but no. The definition of efficiency in physics & engineering is useful energy output divided by input. That's just what efficiency is.


A radiator may be more efficient
radiating heat if the water is at a higher temperature.

Radiation from a radiator versus convection is irrelevant to its efficiency. That is more relevant to filament lamps.


Some further examples
2) efficient heating equipment
3) more efficient use of energy
4) fuel-efficient cars (= that do not use much fuel)
10) efficient in something - Modern water boilers are highly efficient
in fuel use.

those are of course the efficiency that we are discussing, useful energy output over input.


5) We offer a fast, friendly and efficient service.
6) This is simply the most efficient way to do it.
7) We must meet members' needs in the most efficient and effective ways
possible.

Generally waffly bs uses of the word

Which has now become common usage. I suspect you still think kinky means
fashionable and gay means happy.

1) a highly efficient worker
9) efficient at something - These magnificent animals were remarkably
efficient at survival.
11) efficient in doing something - He was ruthlessly efficient in
acquiring estates.

again useful output over input, though used with rather less precision


8) efficient at something As we get older, our bodies become less
efficient at burning up calories.

not even true. Old bodies do become less efficient at doing work this calories, but not less efficient at burning them.

Old bodies also become more senile and resistant to change too. They use
the English language less efficiently and still think they are kinky and
gay.

There may be occasions where you might swap the word for effectiveness,
in many instances they are synonyms.

Perhaps English has moved on since you were at school?

It's moved on since all of us were at school, but like most words, efficient still has the same meaning. And like so many words it also gets used inaccurately, imprecisely and for the purposes of promotional bs.

No, many words like 'efficient' have changed. Do you really still think
kinky means fashionable and gay means happy.