What makes a good condenser

[froglet]

Hello please be gentle with me! I have had a big search around, and read our books and things but I still have to ask...

In an inline reflux still, is there a way of calculating how much copper tube is the optimum amount to use in your condenser?

We want to build our condenser with a tightly wound 'double helix' style coil to pump the water through, to increase the surface area for the vapour to make contact with.

However we dont want to go overboard and build a condenser that is a million miles long. We just want to make sure the one we build will handle Froggy's pride and joy - the 2400W heating element. And not just handle it, but work well!

The closest I came to having any real joy was the 'wee calculator' on the parent site, in the condensers section. But it seems to deal mainly with worm style condensers and liebig ones.

Can someone point me in the right direction? Even if the calculations are very complicated I'd like to have a go at working it all out.