Any bizarre CH layouts / controls?

[uselessFCUK]

As a spark with diy plumbing experience I find myself penning differing layouts and control of wet central heating systems... just out of boredom and as I've been doing a little DIY in my previous home and now in this new one.

We currently have a gravity DHW pumped CH vented system off a BBU, with no control on cylinder temp, the upstairs rads heat up when on HW only and two stats in different rooms (one of which there's no rad).

Interested to learn of any bizarre / outrageous / dangerous / useless CH systems you guys have experienced that have really stuck in your mind.

Regards
UF

[wiggikins]

Remember an Asian cousin who seemed to think that a Multipoint could do 8 rads as well as hot water!