Baxi [E50] fault codewhat it means and how to fix it

E50 is "Hot Water NTC Fault" in the ten-code table Baxi printed for the Duo-tec Combi HE A, Platinum Combi and Platinum+, and Baxi's manuals single it out for its display form: "E50 is shown as 'E' then '50'", because the number fits the two-character facia without being split. The thermistor sits on the domestic hot water outlet of the plate heat exchanger and tells the board how hot the tap water is, and when it reads open or short the board cannot control the tap temperature.

Baxi's professional page gives the meaning as "DHW NTC sensor fault (tank boiler) — short circuit/open circuit", the "tank boiler" reflecting that on a system boiler with a cylinder sensor the same input is used. The Platinum user guide groups it with the component codes: "E20, E28, E50, E125 & E160 indicate faulty components. You should make a note of the displayed error code and contact your installer or service engineer."

No reset is offered and none is useful. What E50 does to the household depends on the boiler: many Duo-tec HE and Platinum owners find the heating still runs and the hot water either stops or runs at a fixed, sometimes uncomfortable, temperature. On the digital-display generation the same fault has a different number, E321, with the same meaning; the 600 and 800 tables do not print E50 at all. The sensor is inexpensive and, on these combis, reached from the front once the case is off.