A have a vaillant ecotec boiler and when it fires up the fan is very noisy is this right

you might have a small cold water leak

USE A ELECTRIC METER AND CHECK FOR 120 VOLTS AT CIRCUIT BOARD AT LINE IN AND COMMON , IF YOU DO HAVE 12 0 VOLTS THE LOOK FOR TAPPINGS FOR 24 VOLT OUT PUT MAYBE A BAD TRANSFORMER OR CIRCUIT BOARD

wrong category. If you post to correct category you will get a faster response.

Sounds like it is trying to constantly ignite ,the clicking will be the electrodes trying to fire,change the ignition electrode.

my eco tec wall mounted boiler cuts out after about 10to15 days this unit was fitted in august this year

F.22 Dry fire Too little water in the appliance, water pressure sensor defective,
cable to pump or water sensor defective, pump blocked or defective,
pump output too low

try to enter here all informations and you can find the manual: http://instructions-manuals.com/search.php?cmarque=VALLIANT%20&modele=ECOTEC%20PLUS%20824

David,

The fact that you're getting a little burst of domestic hot water suggests that the boiler is capable of circulating hot primary loop water through the heat exchanger, but doesn't necessarily do so when it needs to.

What seems to be lacking is a recognition that domestic hot water is now being drawn off, and that the boiler needs to fire up and divert the primary flow through the heat exchanger.

A good place to start might be the flow switch (usually in the bottom of the boiler, where the cold water supply comes in) or the electrical connections to it.

A.