bathtubfaucet
I have a leak from the hot handle of a 3 knob tub faucet when the water is running. I am able to turn off the hot water because I have access to the hot water heater but I live in a condo that does not have a water shut off for just my unit. I have to request the management company to shut off the water which affects several units. There is also a charge for this request.
Can I replace the washer by just shutting off the hot water?
Try tightening the packing nut (the hex part the stem goes through) a little. That's what it's for. Don't overdo it. The "packing" is the material that seals around the stem - the packing nut compresses that material. On a valve that is not used often, actuating the valve does commonly cause it to leak, as things have "set." Tighten a little, wait, tighten a little more, wait - try to sneak up on it, as the pressure is a balance between enough to seal and little enough that the valve turns easily.
Diverting the leak up to the shower head using the diverter valve should not be a problem, but your assumption that fixing it will be "pretty easy" may not prove to be true. You are correct in that hot and cold supply to the tub/shower valve needs to be shut off. Sometimes apartment shower valves have built in shut-off valves called integral stops.
Sometimes apartments are equipped with individual remote shut-offs. Sometimes the whole building will need to be shut down. Removing the valves may require special tools like deep valve sockets.
The repair may be simple washer replacement or may require more complicated cartridge replacement.
I do recommend that you try it but make sure your landlord is cool with it in case something breaks, and have back up shower facilities available in case it ends up being out of service for a while.
Best Answer
YES- on 3-handled tub/shower valve units the supply water is delivered seperately to the hot and cold sides; turning off the hot water supply will allow you to work on the hot side valve.
Because multiple units will be affected you should do some research on how these are repaired prior to turning the supply off, to minimize down time.
Your description of the problem ("leak from the hot handle... when the water is running") is indicative of a problem with the valve's packing. I recommend rebuilding the whole valve while you have the water turned off (bibb washer, packing, grease the stem thread, seat if necessay, etc.) Keep in mind that there are many (many, many, many) brands, models, and configurations out there and there are no "standard" parts. Washers come in a bunch of different sizes and types.