Lots of people on the Ormerod forum complained about long bed heating times to ABS temperatures. 120W isn't quite enough power. The solution most of us have adopted is to use a 12V PSU with a voltage adjustment allowing it to be turned up to 13 or 14V. These PSUs cost very little on eBay, less than GBP20 here in UK for 25A one. I printed a cover to go over the mains terminals, see [www.thingiverse.com].
Another thing that helps is to put an insulating mat on top of the bed while it is heating up.
Another thing that helps is to put an insulating mat on top of the bed while it is heating up.