hello i have a navien 210a tankless model installed in a new house in the spring. I have received this error message three times in the last month, 048 . According to Navien tech support that error code is a gas pressure issue. MY contractor has been back and has checked the gas regulator and the gas switches on the unit itself. He says the pressure is set exactly where they recommend. Anyone esle have this issue any guidance will be greatly appreciated.