Thanks for your replies everyone.
I don't heat mine. I just load them in the extractor and let them spin.
Australian honey is notorious for having a low moisture content, and therefore a high viscosity. Sometimes they can be hard to extract even when heated. Its also getting colder. A neighbour tried to extract some a few weeks ago and got a little irritated :-\.
I know a lady who runs 900 hives she has a hot room she puts the Box's in for a day before she extracts.
I know a guy who has several thousand and does the same, but he still has trouble sometimes when the water content goes down to like 12%. I have six hives. hmmm, maybe I could build a very small hot room......
Look at this:
Yeah that was helpful thanks. It got me thinking and I realised I have an old lizard enclosure which I turned into an terrarium. I has light bulbs in it for heating, which are controlled by a thermostat. I'm thinking if I clean it out I can use it. It will hold at least two 8 frame deeps. I could also line it with polystyrene to in insulate it more. If I wanted to get really carried away I could take the thermostat, and mount it into an old cupboard or purpose built container like the one in that link. I could then connect it to light bulbs, element, hotplate or whatever I want to use for heating. hotplate might be a bit of a fire risk actually.
So I'm thinking it just took a little encouragement ;).