On Saturday, 4 March 2017 07:45:11 UTC, jim wrote:
"Dave Plowman (News)" Wrote in message:
In article ,
jim k wrote:
None of the heat is wasted.
Ergo efficiency is always 100%


Bollox! I want to warm the room not the underdrawing to the boiler
& back....

Then you must thing a rad has hot water in, room temperature water out...


Nope.
You seem to thick pipework to & from a radiator emits no heat...
Especially in draughty cellars..

You seem to be trying to tell me a length of copper pipe is as
good at heating a room as a radiator...


Exactly so.
It depends how long a piece of pipe it is.

Pipework heat is taken into the detailed heat calculations in some buildings