I hope someone might be able to offer a suggestion as to what the problem is with my condensing combi-boiler. The boiler is nearly 2 years old and approximately 9 months after it was installed it started making a noise when a hot tap was turned on. The noise only lasted for a couple of seconds before stopping and was only really a slight annoyance so we just left it. From then until now though, the noise has increased in loudness and also length of time it lasts for. So much so that we can't turn on a hot tap at night, otherwise it would wake the whole house. It's a hard noise to describe, but it sounds kinda like a plane taking off. No gurgling, just a whooshy noise. It never happens when the rads heat up, only when a hot tap is turned on. The green pressure gauge on the front of the boiler shows the needle is in the right area. I'll need to get someone out, but I don't want to be ripped off just because I'm female and it looks like I don't know anything about boilers. (Which I obviously don't, lol.) Be grateful if anyone has any ideas? TIA.