why replace the fan? thermocouple or the interrupter is more likely the cause.
check this first though.....the fan should run slowly when there is no demand to keep a fresh supply if air for the pilot. check it is running. if its not then check the flow switch under the pump and slightly to the right. this has a pin which moves in when the pump is running, when the pump is not running the pin should come back out and put the fan to slow speed, the pin often gets stuck and doesnt let the fan run.
if it is stuck the most likely cause is the venturi hole inside the flow switch is blocked.
boiler serviced recently, and fan replaced as it was sticking - my username confirms I am becoming slightly 'off colour' with continued breakdowns etc.. will investigate venturi to see if this prevents pilot going out - presumably a fan running at hi speed is likely to blow out the pilot??!!
no, the fan doesnt run at all when there is no demand and the pilot dies from lack of air in the chamber, or at least gets so small it misses the thermocouple.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local