I was going to say the same as Hazel, he's probably not happy with the change in the house. He will probably keep wee-ing in the same place now unless you can make it smell totally differently, especially something chilli or vinegary which his delicate nose won't like! Do you have somewhere different you can put a litter tray for him? I found with mine, when I take her to stay with someone when I go away, just showing her where the tray is located and dipping her paws in is enough for her to always go in that spot even in a strange house.

__________________
Life may not be the party we hoped for but since we're here we might as well dance