Noritz Tankless Combination Boiler

[Ryan Cohen]

I have a rental property that has a natural gas Noritz tankless combination boiler for heat and hot water. The unit is about 6 years old, and has constantly had problems the 3 years that I have owned the property. Particularly in the winter, the unit throws error codes as the intake pipe usually freezes. I have tried multiple things - changed the intake pipe to a T so it could vent from both sides, and even have vented the unit from inside the basement and it stills gets the same error code. Additionally, the unit will typically throw different error codes as well which are fixed by resetting the system on/off. I am constantly having my tenants text me that they have no hot water, and this is more to happen in the winter when it's most important. My question to everyone is what system do they have for their multifamily properties? Do you think I should still mess around with Noritz or should I go a different route? From my experience, they are really fussy and find a way to throw an error code. One plumber mentioned that these units are lemons, and suggested that I replace the unit with a cast iron boiler and water heater which will have better luck than the wall mounted Noritz unit. I understand boilers need yearly maintenance, but I am really looking for a solution to sort of forget about having yearly problems typically around the winter with this unit. Any info on this is appreciated. Let me know what you recommend.