Fan or Heat Recovery Unit in bedroom

[Butterfly44]

My master bedroom has 2 outer walls. It's a Victorian building so no cavity walls. There is an en-suite with an extractor fan. However the bedroom walls and ceiling have been having condensation and mould. I'm trying to increase ventilation to help, though do try and open windows often. So I'm thinking of replacing the en-suite extractor fan to a humidistat one, and wondering how to increase ventilation in the main bedroom. A fan might be noisy? Reading up, a heat recovery unit looks a possibility. Has anyone had one installed, are they quiet enough for a bedroom? Thanks in advance

That appears to be a disused soil pipe sticking out of the floor. It seems to be brown glazed clay which is frequently cracked or broken and leaking. It looks to me like the damp is leak related. There are some other old pipes under the floor. I'd ask around for an experienced plumber.

Also, look for nearby manholes.