Zipster
I assume you mean S23,
If so no wonder why you have sulphur smells; that stuff really stinks; it is about the smelliest yeast I know off.
Basically you should be looking at fermenting at 12c
Then once you hit your FG, raise the temp up to 16 for a couple more days. This will allow the yeast to eat up all their 'poo' (sulphur smell) .
Then you should look at lagering it for a couple of weeks to finish it off.
PBR
I haven't really noticed a sulphur smell from any infected brew. Not saying it doesn't happen, but I have never smelt it. Infections normally have a different stink to fermenting of lager yeasts. Also normally you will see visual signs on top/slightly into the wort. Finally always taste the beer before bottling/keging.
QldKev