Leaking tub faucet and localized water shut-off

[ChrisB]

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!

 

[FishScreener]

Once you depressurize the house, the water in the tank will stay in the tank. Domestic water heaters feed in and out from the top. Just be sure to turn off the water heater first.

So: first turn off the water heater; second turn off the water; then turn on the valves, to depressurize the system; then make the repairs.

Personally, I’d do the cartridges while I had it apart. It’s a few bucks in parts, and a worthwhile belt and suspenders kind of approach.

Murphy’s law says that if you just replace the springs and seats, the cartridge will be bad, and you’ll just have to tear things back apart.

 

[Diehard]

Just a thought.
You do have the capability to turn ONLY the hot water off, at the cold water INLET to the water heater. That should allow you to determine if it's the hot or the cold side.

 

[TomFOhio]

Turn the main water valve off and the hot water heater will also be off since no water can go into it. Turn it to pilot or if electric turn breaker off.
Open the hot and cold faucet someplace like said and then repair your faucet. Change both like suggested.