How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Plumberpro Your Own Question
Plumberpro, Home Appliance Technician
Category: Appliance
Satisfied Customers: 634
Experience:  Heating and hot water heating appliances experienced
Type Your Appliance Question Here...
Plumberpro is online now

My CH system operated by a Honeywell St9400c. Programmer has

Customer Question

My CH system operated by a Honeywell St9400c. Programmer has an intermittent fault. At about 6.20pm most days the boiler switches off for no apparent reason. The thermostat is set for the heating to be on as is the St 9400c and the lights are on but the boiler is off. We have had the boiler checked twice by Worcester Bosch and there are no recorded faults. The only way to get the system operational again is to switch off the boiler which also cuts the power to the St9400 c and then switch the boiler on again. It then works normally switching on and off in accordance with the timer until the following evening.
Any suggestions as to likely cause and solution would be appreciated. The whole system is approx 2 years old.
Ps this happens whether or not the hot water is set to come on at the same time.
Submitted: 3 years ago.
Category: Appliance
Expert:  Plumberpro replied 3 years ago.

Hi . I would recommend that when it switches off next, with a multimeter/ voltage tester a check should be made to see if there is still power to the boiler ROM the external controls.this would confirm whether it is a boiler fault or an programmer , room stat fault.

JACUSTOMER-ihrik80z- : Thank you. We know it's not the boiler so I had expected some guidance on what to do to fix the programmer. I shall arrange for someone to call and please confirm there will be no charge for this answer.

Sorry , but anyone looking at the system would want to confirm that first. Sorry to dissapoint you with good practice