Honeywell technical support
This boiler, from memory, has an electric diverter valve.
If the system has dirty (sludge/scale laden) water then the diverter valve may not return under spring pressure, and therefore not divert all of the hot boiler water to the hot water heat exchanger, leaving some going to the rads.
If I am right then the rads will not get fully hot.
If the valve has failed completely, or electrically, then the rads will get fully hot and there will be no hot water output (hot water will be cold).
×