12v Fan

whjohnson:

Years ago, building regs did not require forced mechanical ventilation if a source of natural ventilation was present.

To translate, basically you did not need to fit a fan if a window could be opened in the same room.

However, with the move towards this green nonsense and the widespread installation of 'warm roofs', the building regs changed, and now you have to fit mechanical ventilation, even if there is the facility of opening a window instead.

Moreover, there would appear to be a requirement for any fan to be a timed in order to clear any residual humidity after the light has been switched off. Most fans are wired to come on with either the lights, or via some kind of (usually unreliable and short-lived) humidistat device, so you will have to provide a 'permenant live' for the fan timer in order to comply with building regs.

In order to site the transformer, is there not any way of situating it on the other side of the wall from the bathroom?

That is what I am doing on my present job - 3A fused spur, then transformer, then 3 pole fan switch and 12VAC cable going through wall to fan inside bathroom from outside.



unfortunately the bathroom is tiny, the wall they originally wanted it on was going to be right next to shower head, I can’t go further to door as the window goes across there. Then your at other wall. 

The wall opposite the shower then towards the door is back to back with neighbours , so it can’t be put there, unless the neighbour agrees ?.. Leaving the only wall being is inside the bath area. Reason I cannot go for a huge transformer fan . If I can have one with a little one, there’s a chance I can find some cavity to try slot it in

whjohnson:

Years ago, building regs did not require forced mechanical ventilation if a source of natural ventilation was present.

To translate, basically you did not need to fit a fan if a window could be opened in the same room.

However, with the move towards this green nonsense and the widespread installation of 'warm roofs', the building regs changed, and now you have to fit mechanical ventilation, even if there is the facility of opening a window instead.

Moreover, there would appear to be a requirement for any fan to be a timed in order to clear any residual humidity after the light has been switched off. Most fans are wired to come on with either the lights, or via some kind of (usually unreliable and short-lived) humidistat device, so you will have to provide a 'permenant live' for the fan timer in order to comply with building regs.

In order to site the transformer, is there not any way of situating it on the other side of the wall from the bathroom?

That is what I am doing on my present job - 3A fused spur, then transformer, then 3 pole fan switch and 12VAC cable going through wall to fan inside bathroom from outside.



unfortunately the bathroom is tiny, the wall they originally wanted it on was going to be right next to shower head, I can’t go further to door as the window goes across there. Then your at other wall. 

The wall opposite the shower then towards the door is back to back with neighbours , so it can’t be put there, unless the neighbour agrees ?.. Leaving the only wall being is inside the bath area. Reason I cannot go for a huge transformer fan . If I can have one with a little one, there’s a chance I can find some cavity to try slot it in