DHW flame drops on baxie 105e

[mickyq]

hi guys. when the bolier has been used for a while the flame for dhw drops to low and the water runs cool at the tap. theres a rubber tube from the gas valve to the underside of the burner compartment. if i squeeze this tube the flame goes up. ill probably need an engineer to fix it but does anyone know what could be wrong?

 

[diesel_ltd]

Plate heat exchanger blocked

 

[mickyq]

cheers diesel. i tried swapping the heat exchanger but no change. it wasnt a new one but it had been cleaned.

 

[Billy Bob Bob]

check gas pressures,thermistor on dhw

 

[Plucky]

Pull lead off thermistor and see if it hold max rate. If it does then thermistor gone. If not then look at modureg coil