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Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3632
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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I have a vaillant combi boiler and a Siemens remote sensor.

Customer Question

I have a vaillant combi boiler and a Siemens remote sensor.
I am getting hot water, but when I set the sensor to run and auto and increase the temperature for the radiators to turn on the boiler doesn't work.
Any ideas?
Submitted: 2 years ago.
Category: UK Plumbing
Customer: replied 2 years ago.
The green light on the reciever unit is on and the thermostat unit looks normal. I have tried resetting but with no joy.
Expert:  Andrew Smith replied 2 years ago.

If the green light is on, the the receiver has got the signal and turned on.

It could be a wiring fault or could be the relay in the receiver has faiiled.

We could try wiring around it to see if the boiler fires up?

Customer: replied 2 years ago.
Thanks Andrew. How complex is that process?
Expert:  Andrew Smith replied 2 years ago.

If you take the cover off the receiver you will see 2 sets of wires, one for mains power and a pair for the heating.

If you turn the power off and take the pair out and put them both in the same terminal, effectively linking out the thermostat.

When you turn the power back the boiler should fire if it is a thermostat fault.