Why the flame remains always at the same size? That is why the hot water cannot be kept at a constant temperature. Burner keeps swtching on and off. I think it may be the thermistor? Or perhaps the the ignition PCB or the control PCB or both?

Thanks in advance for your help.

Manuel., October 2012

Change NTC hot water that's easy option if not the hot water heat exchanger need clean up not PcB

ltd, October 2012