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Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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Promax 24he +. Heats 2 hours with occasional hot water

Customer Question

Promax 24he + . Heats for approx 2 hours with occasional hot water demands working ok. Fault is no heating after 2 hrs. 60° flow from exchanger going to plate exchanger & back to main exchanger, heating cold. Baxi say 2.5k ohm across heating thermistor= 80° &thats why its not wandering why the diverter valve would circulate 80° water round the boiler instead of the rads. Mechanical time clock is the only control.
Submitted: 1 year ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 1 year ago.

It sounds like the divertor is not switching across to heating again after it fires up again.

Are you able to check for voltage at the motor to see if it has failed?

Customer: replied 1 year ago.
Hi andrew, the motor hasnt failed. Whilst the heating call dose not fire the boiler the hot tap does and the valve extends to divert the water. Also after time has allowed the primary water to cool the boiler can be reset and functions properly.
Expert:  Andrew Smith replied 1 year ago.

Does the valve fully open when on heating only?

Does the boiler fire when it does?

Customer: replied 1 year ago.
I'll try that tomorrow & get back to you. Thanks for your help. Iain
Expert:  Andrew Smith replied 1 year ago.

No problem, let me know

Customer: replied 1 year ago.
Appologies for the long delay. After further testing im getting 240 across red & black to the diverter. Ive noticed that when in fault condition the actuator pin is "slack", it slides back into its housing when the actuator is turned upside down rather than remaining flush with the surface of the actuator. Im guessing its the actuatir at fault?

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