Water vapour condensing in pipes?

[flanagaj]

Whilst researching about MVHR systems, it got me thinking about whether warm moist air from bathrooms will condense in the ducting before it has reached the MVHR unit.   If so, how do the systems handle this as otherwise you will have water collecting in the pipework which will pose a Legionella risk?

[RobLe]

The pipes should be insulated, so you’d not expect much condensation.  They shouldn’t have dips in them for puddles to form.  And that air is on the way out, it’s not coming back in ever!

[MikeGrahamT21]

All of my extract pipes and corresponding manifold are as dry as a bone, have been since I installed them nearly 4 years ago 

[JohnMo]

1 hour ago, flanagaj said:

water collecting in the pipework which will pose a Legionella risk?

You should be sloping back to the terminal or towards the MVHR unit. There should be no collection of water. Even if there was, the amount air travelling down the pipe would soon mop it up.

 

Legionella growth is zero below 20.