Hot water & IPC

[John110]

In a project I am just replacing two hot water heaters 990 MBH /Each (for the capacity might call it Boiler). There are two 400 gallon hot water storage tank hanged from ceiling. The building is in USA and built 1998. The building is maintenance facility with partially offices. I am not seeing any main mixing valve inside the mechanical room to control the supplied hot water temperature to showers and sinks at 120F, to meet the IPC section 408.3 & 409.4 temperature requirements. I don't want to add a main mixing valve inside the mechanical room since the piping system isn't separated. This code requirement was in force during the construction of the building in 1998. Should i consider that all showers and lavatories and sinks are using temperature controlled fixtures. Since i don't have the original fixtures submittal , I have no way of finding this. The existing drawings also don't show anything related to this. Please advise.