Breif re-cap as follows.
Downstairs bedrooms x 4 built into steep hill so all have one opening
window, and nowhere for a through ventilation (in winter) as no trickle
vents or nothing installed leading to condensation esp. as bathroom also
downstairs with limited ventilation.

As I will be ripping out all radiators in bedrooms and re-plumbing all
pipes to be above solid floor rather than embedded, and re-fitting new
radiators, I had a thought.

Glancing through bes.co.uk (or some other) I stumbled on "baffled"
ventilation blocks (or simmilar) which, I am thinking might be ideal to
fit from room to outside but behind radiators.

Thereby, convection of radiator may well draw fresh cooler air and heat
it up as it is convected up with heat. I am thinking it would hugely
reduce those icy draughts from ordinary trickle vents at the same time
as being invisible within the room.

Any thoughts / precautions on doing this? good idea or bad?

oh, I still have the old un-used chimney flue open into the downstairs
airing cupboard which creates a reasonable draw to change air shoud
inlets be installed.

Cheers
Pete

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