More Vanda Help Please!

[poppy86orchids]

Hello everyone,

I posted about a Vanda that has been passed on to me. Well it has shot out a new aerial root which I though was a sign it was doing ok. Well now, the root is still growing but the leaves are turning paler in colour and drooping. what's wrong with it???
I am watering it by alternating between soaking its roots for 15 minutes every other day. The day I do not soak it, I mist the roots.
I live in the UK and it is quite cold at the moment. I have the vanda in a hanging basket, with it's roots in a vase (not touching any water), in a bay window to get maximum light. It is in a spare bedroom so the central heating does not affect it - as it is on very low in that room.

What am I doing wrong please?