Ok, so I finally decided to stump up the cash for the airer... it arrived a couple of days ago, so yesterday I washed a load of nappies... carefully layered them on - most 1 layer thick all over, but 2 v thin ones were doubled up.
Then I washed towels and layered them over the outsides to trap the hot air in...
...the airer got surprisingly hot... the air inside felt warm... there was condensation building up on the poles at the top of it (when I moved the towels later to peek in)... the room got nice and warm...
... and 10 hours of it being on (and about 8 hours of it being off) later I had 1 nappy that was almost dry, some half dry towels and the rest was sopping wet still. :(
Luckily the weather cheered up this afternoon, so a couple of hours outside plus an hour on the radiator this pm has dried them, but really... what am I doing wrong???