Ducted heating, Murphy's again

[Tiger]

Why is that as soon as you come to turn the ducted heating on because it's beginning to get colder, it won't work . The heating hasn't been used for a while but the pilot is ok, thermocouple ok. I think it's the switch. From what I remember, when you turn it on, it should make a clicking noise and you hear a whoosh sound. The clicking noise is very faint and there's no whoosh. I have taken the top panel off the control switch and it all looks ok ie no broken wires. What should I test/look for? Any advice appreciated.

[SilentButDeadly]

What should I test/look for?

A certified plumber and a new heater control. Otherwise the next whoosh you hear could be your house...........

[FXST01]

A certified plumber and a new heater control. Otherwise the next whoosh you hear could be your house...........

but that next whoosh would be warm

[built4thrashing]

do you know what brand the heater is? Most new heaters dont have a pilot and self ignite when thermostat asks. Im guessing thats what the clicking noise you hear is. if pilot doesnt start then it could be the thermo couple, the pilot jet or the gas valve.(I assume the gas valve is turned on at the heater. )
On a last note it is recomended that all ducted heating units be serviced every 2 years to ensure correct operation and its also a warranty requirement on some brands too.

good luck