Like many things: "it depends". If your current system can heat the house on the design day with 55°C/130°F water, you don't need to change piping or rads. (My

Like many things: "it depends". If your current system can heat the house on the design day with 55°C/130°F water, you don't need to change piping or rads. (My house was in this situation as the original system was designed for gravity flow and so was massively oversized for a modern pumped system.) If your house has minimum sizing of baseboard radiators and the design day flow temperature is 82°C/180°F, then you need to update at least the emitters and maybe the piping.