jon wrote:

Fredxx wrote:

jon wrote:

What is this nonsense, heat is dissipated by radiation, convection or
conduction so how come efficiency becomes a problem.

For conventional central heating radiators most heat-loss is through
convection. Air is a poor conductor.

It seems there is less overall air flow for a tall radiator than long
for a radiator with the same area and construction.

So hardly nonsense.

So where does the heat loss go other than in the room..?

stays in the hot water and is emitted by a radiator into a different room.