Originally Posted by
speedball1
Your Delta valve has seats and springs instead of a cartridge. Perhaps the hot water pipes were disturbed or you have mineral build up in the heater but the hot water seat is blocked in both valves.
To access the valve, remove the handle and the face plate. You should see screwdriver stops where the water enters the valve. If not turn off the water. Now unscrew the bonnet nut and pull out the stem unit assembly. This will expose the seats and springs. Remove them and check the opening for crud or blockage. Now, while the valve is open) turn on the hot water and flush out the supply line. You should have a full stream. If so, reassemble. If not then the blockage is further downstream and you may have to call in outside help. Good luck, Tom