Knocking holes in the wall for extractor fans

[lethargic_man]

I have a running problem in my kitchen with mould on the walls during the winter. I suspect it's because I don't use the cooker hood fan while cooking, but even if I did, it's just got a filter in it: there's nowhere for the steam from cooking to go. It seems to me I'm going to have to get a new cooker hood with a proper extractor fan, and that, it seems to me, is going to require knocking a hole in the wall to let the extracted air out. (Either that or the window, but the secondary glazing would make that problematic.)

Does anybody with experience of these things have any comment to make on this? And of my London readers, can anyone recommend me someone to do the appropriate hole-knocking?

[ETA: Oh, I hadn't realised I'd blogged this already. Though the solicitation of recommendations still stands.]

Comments

[pseudomonas.livejournal.com]

Are you going to get one of those heat-exchangery whatsits that allows fresh air in without making the place chilly?

[lethargic-man.livejournal.com]

This is why I posted this on LJ—I didn't even know such things existed! (I assume(d) extractor fans normally just push air out, and replacement air is pulled in through/around the door by the partial vacuum thus created.)

[pseudomonas.livejournal.com]

You can get these whirly things that pass air in and out through or past a chunk of high-heat-capacity material, I think.

[pseudomonas.livejournal.com]

https://secure.wikimedia.org/wikipedia/en/wiki/Heat_recovery_ventilation

Physics

[miss-whiplash.livejournal.com]

Moisture migrates to the coldest place in its local vicinity and condenses there. When it is colder outside, opening the window will reduce humidity, and closing the kitchen door will help to prevent heat loss from the rest of the house and moisture from spreading around the house. If you can't bear the window open when you are cooking, open it once you have finished for twenty minutes or so, closing the door behind you. It's a cheap, low energy solution that will work unless you have internal walls colder than outside.

Unless you are reducing a sauce, using lids on saucepans will help too.

If your fridge defrosts, drains out the back and then evaporates the water in the room, then it might make sense to fast defrost it and pull ice out occasionally.

Re: Physics

[lethargic-man.livejournal.com]

Thanks for the advice, but all the above is what I do already (plus, for the last year, a dehumidifier on loan from bluepork), and it's still not enough. Though some of that is no doubt due to the fact my place has no central heating, and also that fungal spores lurk in all manner of difficult to get to places, waiting for the colder season to return, in which the carrying capacity of the air is much lower.