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Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
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Honeywell st9400c control panel. the panel is illuminated and

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honeywell st9400c control panel. the panel is illuminated and the hot water is working, but the buttons are frozen and i am unable to turn the heating on. have tried turning off and on again with no joy. the time and date are frozen too? any ideas? thanks.
Hi ,there is a lithium back up battery inside, replace that, if still the same the unit has failed. Replace with the same model and you can use the same wired back plate.
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