Upon arrival I was point to the toilet in the master bathroom. This toilet had a leaking fill valve. This can happen for two reasons, age or a pressure issue caused the fill valve to break. After performing a safety check of the home we discovered that the pressure regulator was working properly, but at first we had elevated pressure. This pressure was elevated from the baseline which was 55 psi After performing a thermal expansion test. We discovered there was a thermal expansion issue. After providing options and upon approval, we rebuilt the master bathroom, water closet, installing a new fill valve, a new flush tower gasket, and replaced the supply line. We began addressing the thermal expansion issue by performing one final test, pressurized both the thermal expansion tanks to verify whether they would hold pressure or not. Both thermal expansion tanks held pressure. We set both thermal expansion tanks to 65 psi. Most likely both thermal expansion tanks were not pressurized when