On Thu, 6 May 2021 11:55:00 -0000 (UTC), jon wrote:


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

Because efficiency is a measure of 'how well' not 'how' a system
works.

With a tall / narrow rad, most of the air rising up / around the rad
will already have been warmed by the lower sections and so only the
lower sections will be working 'efficiently' (hot rad cold air V hot
rad already warm air (= lower temperature gradient)).

With a wide / low rad, much more of the height / length of the rad
will be transferring the heat from the rad air room and so it will
(for the same area) be able to transfer the heat to the room
efficiently / faster.

It is this way because the air is moving over the rad by natural
convection and that means vertically. Make the rads 'fan assisted'
and, (depending on the design) make far less difference re the
orientation.

Cheers, T i m