Thought it may be something like this mate, seen similar things during my years on the building, steps or driveways built up over a damp course, walls tanked which will never cure a leaking roof, the list goes on and onYou’re absolutely spot on. The whole point of the system is to blow air in; there’s an extractor in the utility room, which subsequently allows a flow of air. Therefore, no condensation and no damp.
However, it was a waste of money. There was three cases of damp in the house when we moved in:
1. Damp patch on the dressing room wall and on the wall out it the hall, both of which caused by a leaking roof. The repair had been botched a few times during their ownership. We had the roof repaired properly, no more damp.
2. Blistering paint from water ingress on the supporting walls of the patio doors. Them twats painted over it just before we moved in. We had the builders take a look and the damp course stopped about 10cm short on both sides. Now fixed.
3. Damp on dining room wall under bay window; I don’t think they knew about this one. A layer of concrete on the front patio adjacent to the outside wall had been built too high, so there was nowhere for the rain water to drain. Also fixed.
The people here before were academically pretty bright. However, as with a lot of academics, they didn’t have the brains they were born with. It seems that whenever there was a problem with the house, they threw money at the symptoms and not the cause. If they’d called proper tradesmen to find the source of the damp and have it properly fixed, they wouldn’t have needed to install that stupid vent system and could’ve simply opened a couple of windows like any normal person.
It never ceases to surprise me how clever people cant seem to see the easy solution to a problem and just either bodge it up or suffer it for years