NO HEAT FROM HEATER. PIPES TO AND FROM HEATER MATRIX ARE BOTH HOT. CABLE CONTROLS ARE FUNCTIONING CORRECTLY. MATRIX HAS BEEN BACK FLUSHED. NO PROBLEMS WITH FLOW RATE THROUGH THE HEATER MATRIX.
COOLING SYSTEM HAS BEEN BLED ON NUMEROUS OCCASSIONS BUT NO IMPROVEMENT. HAS ANYBODY ANY IDEAS OR COME ACROSS SIMILAR PROBLEM.

GEOMAN, December 2004

There could be a break in the linkage which moves the heater from hot to cold. Perhaps the cable mounting has broken? Hence stuck on cold.

Have you tried to move the hot / cold paddle manually?

Paul, September 2007