Hi everyone; I need some advice on a small plumbing 'challenge' I have ahead of me. My 27 year old bath tub faucet is slowly dripping (it's a Delta, two individual knobs for Hot & Cold respectively); and thanks to some videos on YouTube I suspect that the seat and spring assembly that needs to be replaced. It does not look too complicated to repair. The problem is that I cannot determine whether it is the hot or cold that is dripping, so I plan to change both. Where I am looking for suggestions... in the absence of any localized shut-off valve I will turn off the main water to the house which will cover me for the cold side, but for the hot side, I am unable to locate any type of shut-off valve at the exit of the hot water tank; any ideas on how I could avoid having to drain 60 gallons of hot water to change a small spring/seal? Thanks!