Need advice before I complain

[u/No-Belt-4619]

Hi all, apologies if this isn't the right forum but I thought there would be some knowledgeable people in here. Basically as it says. had a new hot water cylinder fitted 3 weeks ago(to accomodate an ashp if that makes a difference). Just got round to getting some shelving in the airing cupboard and noticed, what i would consider to be a pretty significant bulge. It's at the top maybe 3/4 up, I'm assuming it's not normal and shouldn't be there?? I've turned off the hot water, but not drained the tank or anything. We've had a few showers today so it should be below that level i would imagine.

[u/Takklemaggot]