Where does a ceiling bathroom extractor vent to if it is nowhere near an external wall?

[rocketz]

Thinking of buying a flat on the second floor of a modern block (built 1996). It is currently let out but the landlord is selling up. The bathroom is not on a external wall so has no windows. There is an extractor fan in the ceiling, but the current tenant says it hasn't worked for the 3 years he has lived there. Surprisingly, there is no mould. The bathroom will need some refurbishment, so we can get the fan fixed as part of that. However, my question is, where would the extracted air go if the fan is in the ceiling nowhere near an external wall?

There is another flat above.

Ours goes up into the under eaves of our loft extension and out from there.

There will be a ducting hose from the fan to a vent in the external wall.

It will most likely go along a duct behind (above) the ceiling of the bathroom and whatever room is between it an outside, then out through a vent in the wall. (Eg between joists, or though them as a lot have an open structure made of steel struts)

A fan that has to blow air along a duct needs to be extra powerful to get enough flow, so bear that in mind (mention it to the contractor) when any bathroom work done.

(Your landlord should take this seriously because of awaabs law)

If it doesn't work at all, it's probably turned off. Depending how they have been installed some bathroom fans have to be low voltage (mine is above the bath), so there will be a transformer somewhere, they should also be configured to be in continuous trickle mode, until the light is turned on, then to stay running for a set time when the light is turned off.

Should be a duct running between the ceiling joists to an external wall, whether this has actually been done or they’ve just stuck in a dummy fan to satisfy regs, I couldn’t say.

my previous flat was built poorly and the extractor fan just went into the wall cavity! But if you don’t have mould then ventilation must be working somehow

Yes, this is a concern. Though as it's a modern building, and the bathroom was built in that position (not converted later), and there's no mould, I'm hopeful all is ok.