if you have use of a blowtorch,solder and flux it is easy enough job to solder a patch onto the cylinder.first you need to turn the cold water stopcock off and open the hot water taps to drain the header tank in the loft. once water has stopped running you need to lower the water level in the cylinder to below the pinhole.to do this you will have to undo the union at the very top of the cylinder,a little water will come out so have some towels ready.spring the pipe to one side so you can push a piece of hosepipe into the cylinder.now you need to syphon off the water into a bucket. now with wire wool clean around the pinhole until spotless and coat with flux. get some copper tube cut off a piece and open it out. hammer it to the shape required and clean this up and flux it. place the patch over the pinhole and have someone hold it down with a screwdriver.now all you have to do is solder the patch onto the cylinder making sure you put plenty of solder on around the patch edges.once its cool,clean up the patch with soupy water.if the patch looks ok reconnect your top pipe and turn the water back on.check the patch to see if its ok,if so jobs a good un. ps use lead free solder.
peter, January 2008