Will it prevent rain getting into my boiler?

That's the name of the game here. A boiler flue cover could be the easy way to help reduce or even prevent rain from getting into your boiler, potentially saving you costly repair costs not to mention the inconvenience.

Many flues are installed very close to guttering and overflow from heavy rain is a prime cause of water ingress into a boiler. A boiler flue cover helps deflect the overflow away from the flue.