During heavy rain, our boiler leaks water out the bottom. I think rain must be getting blown into the flue – is this a big deal? I mean aside from being a pain in the aris having a leak, is it damaging to the boiler?

Looking at the flue, it’s not quite on the hori so I wonder if cutting it back a bit might solve things (will require a biggish ladder, first floor).

Any tips appreciated.

Get a man in pronto. Even if it was being in, it shouldn’t be able to leak out the bottom!

Okay first things first. it would be a potential criminal offence to alter or modify any part of your boiler.. gulp. secondly if the things a modern condensing combi the flue is supposed to be tilted back between 3 and 5 degrees.
the flue is fitted like that so that some of the ‘plume’ condensation washes back through the boiler and exits via the condensate pipework. this liquid is corrosive.
water ingress via the flue is not uncommon how ever as the flue is sealed small amounts should be absorbed via the condesate however if you have excessive amounts then an alternative solution is req. and frankly this should only be considered by a gas safe engineer.
be careful though. not all engineers are competant to work on boilers so check his ID on arrival no gas safe ID stating clearly domestic boilers then dont let him work on it. I would expect him/ her to have to phone the manufacturer and seek there advice.
in the Rochdale, NE Manchester area we charge £45 for the first hour and £35 for subsequent hours plus all parts at trade price.

Do you not have a Flue Cowl on the top of your flue?

not all in fact few modern boilers have cowls . the flue is simply one pipe inside the other the outer pipe is for fresh air in ( for combustion) and the internal one is for the products of combustion ( largely fresh air but includes an unhealthy amount of carbon monoxide and water vapours containing corrsive chemicals as a product of the exhaust gases condensing)

Thks. It’s been like this since installation tbh so I’ll maybe get the guy who put it in to come and take a look at it. Feel like a bit of a Ted asking him since it’s been 2 years and I should have had it sorted ages ago. Oh well.