To me this is one big confusion
http://i12.photobucket.com/albums/a2...ps961db59c.jpg
The thing is at the moment my gas bill is sky high so to help bring it down a bit im hoping that i flick this on for an hour before showers and stuff the hot water will come from this instead of the boiler, but how to I tell if it is plumbed in to work this way?

