Hangzhou hotel uses 50-60 degrees water, and the boiler water comes out and connects the hotel with copper pipes. Now I found that the white towel in the hotel turned yellow in a few days.

Personally, I think it's still the water quality of the boiler. If the chemical composition reaches the standard, it means that the suspended matter such as sediment in the water exceeds the standard! The scheme is right, but I suggest that you install a disc filter and a sodium ion exchanger in the boiler water, and it is of little significance to add a precision filter in the outlet water. Can't you just think about white towels and not be afraid of boiler accidents? According to the regulations, if the rated output of the hot water boiler exceeds 4.2MW and the rated evaporation of the steam boiler exceeds 6T/H, a deaerator must be installed!