underfloor air vent

Hello, I've recently bought a house that was build about a year ago. It has underfloor heating (wet type, running off an air-source heat pump). The other day I noticed the low-level underfloor vents had water around them, as you can see in these photos. 20190101_141831 by hellopaul2 posted 9 Jan...

We have a Victorian terraced house, with timber joists/floor on the ground floor. We have 3 double (flood proof) airbricks to the front of the property, however, at some point in the past a large extension was built across the entire back of the house with concrete floors and we do not have any...

Hi, I recently had a plumber put in a downstairs toilet. For the soil pipe exit point from the house he used an underfloor air vent to the outside to join the main stack (I was not happy when I saw that). Now I need to drill a hole into the wall to replace the lost air vent. I have a 4"...