Not reasonable at all. Efficiency is nothing to do with output for a given area.
Not reasonable at all. Efficiency is nothing to do with output for a given area.
There's more than one way to define efficiency.
Not reasonable at all. Efficiency is nothing to do with output for a given area.
No there isn’t. Efficiency is energy in divided by energy out times 100%. Any other definition is due to ignorance.
In your example, it is not being used in a "general" way, but in a meaningless way.
Efficiency can apply to different aspects of a design. Heat output for a given area is a standard measure of efficiency in all kinds of applications.
Maybe the OP just meant "Will new rads chuck out more heat compared to the old ones?". Can that question be answered without splitting hairs?
It depends on the size and design. The design of central heating is such that a given output radiator is used depending on heat loss calculations for the room. Then a boiler is sized to be able to supply the required energy. If you start putting higher output radiators everywhere the boiler may not be able to cope. But at the end of the day do you need more heat? Are you cold?
No, that is not efficiency.
How do you measure the efficiency of a heat exchanger then?
For a heat exchanger? So if there were say 5% heat loss from the external surfaces of the exchanger it would 95% efficient? That tells you nothing about its performance. You would need the kW transferred (under specified conditions), per m2 or for a specific piece of kit, depending on the details.
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Modern/new rad v the same size old crusted/slugged/painted rad. If it’s hotter, you can always turn it down.