I am preparing to change the sink unit in my kitchen and have just discovered that there are no cutoff valves on the hot and cold pipes that feed the sink. I would prefer to fit these before I go any further but this is an old house and I have never really understood the way the water system works. This is an old back boiler installation and it looks like I would need to completely empty the hot water tank before cutting the hot pipe to fit the cut off valve. If I can't figure out how to do this then it will be a free flowing hot water supply while I am trying to fit the cut off valve. That's alot of water!
Is there anything anyone can recommend that would let me isolate the supply while I complete this work without draining the entire hot water tank? I guess the "freeze" solution is out of the question because it was constantly melt due to the hot water.
Any suggestions please?