I am having a strange problem with my Toto toilet. If I flush the toilet and then turn on the shower/tub or sink faucet, the toilet will run until I turn off the other faucet. When I turn off the other faucet, the toilet immediately stops filling. The tank is filling and going in the overflow tube, not into the bowl. The toilet has to be running when I turn on the other faucet. If the toilet is not running, it will not start just by turning on the other faucet.
It happens whether I am running a shower, or filling the tub so doesn't appear to be related to the drain.
The toilet and sink are on old galvanized pipes, while the shower is on new pex lines.
My water pressure is high - there is no PRV. A couple of years ago I added a thermostatic mixing valve on the water heater in order to turn the temp way up.
Is it likely just a bad fill valve? Replacing it is the first thing I plan to try, but very curious why it would behave this way.
It happens whether I am running a shower, or filling the tub so doesn't appear to be related to the drain.
The toilet and sink are on old galvanized pipes, while the shower is on new pex lines.
My water pressure is high - there is no PRV. A couple of years ago I added a thermostatic mixing valve on the water heater in order to turn the temp way up.
Is it likely just a bad fill valve? Replacing it is the first thing I plan to try, but very curious why it would behave this way.