hello guys, i am doing a job for a m8 and when i turned off the gatevalve on the hot water supply at the cwsc it snapped in the closed position, i am going to insert a rubber bung to the outlet inside the tank but as there will be no pressure to hold the bung in place because the water is not on will i get someone to hold the bung in place or will it be ok on its own, i am a qualified plumber btw, although i have never done this before ?????