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JamesI, Handyman
Category: Appliance
Satisfied Customers: 2083
Experience:  I have repaired and maintained numerous items over the years, from fridges to freezers, radios to TV's.
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Hi. We have an oil-fired boiler with Danfoss controls. the

Customer Question

Hi. We have an oil-fired boiler with Danfoss controls. the water heating control is WP75-RF
The display is working okay but when on auto, on, or boost, the boiler doesn't fire up and we have no hot water.
Can you suggest obvious reasons for this.
thanks for any help you can give.
Harry Houldsworth
Submitted: 3 years ago.
Category: Appliance
Expert:  JamesI replied 3 years ago.
The most common reason is the sensor on your hot water tank is not functioning (calling for heat), so when "On" (eg Boost, On, Auto), the boiler is waiting to be told to heat the water, but the sensor isnt transmitting the call to start up, and thus the boiler thinks the water in the tank is hot enough.

The installation manual can be found here

My suggestion is start at the sensor\transmitter end, check its making good contact with the tank (has it come lose), next check the wiring going to the sensor is it still getting power (this is mains voltage so be careful).
If the sensor looks to be working, I would follow page 7 on wards on the manual, starting with getting the control panel to 'learn' the signal for the transmitter, then look at doing a factory rest on page 11.

I hope this helps you get to the root of the problem.