The homeowner was receiving lukewarm water throughout the house. I checked both water heaters: the tank water heater was set to 130°F, while the tankless water heater was set to 120°F. The issue arose because when the 50 gallons of hot water from the tank ran out, the 120°F water from the tankless heater mixed with it, resulting in lukewarm water. To resolve this, I adjusted the settings on the tankless water heater to allow it to increase up to 140°F. However, at the homeowner's request, I set the tankless heater to 130°F, informing them that this setting could be adjusted. I noted that I do not recommend leaving it at that higher temperature, especially considering that the code minimum is 120°F. Additionally, I observed that everywhere in the house, except for the master shower and the daughter's shower, was receiving lukewarm water. I advised the homeowner to replace the cartridges in these showers. The homeowner has ordered a specialty Delta cartridge, and once it arrives, we