Are MVHR's healthy, can mould/bacteria get into the pipes?

[Doran]

18 months ago we moved to a newi(ish)-build flat with a very oversized noisy Mr BOX MVHR. (Mechanical Ventilation Unit with Heat Recovery)

http://nuaire.info/IandM/671588.pdf

My partner has worries that they are not that healthy as they suck up moist air (and all the other 'particles' that come from the toilet/bathroom) and that there is a chance of mould/bacteria getting in the pipes. And with a (bi)/yearly check up the pipes don't seem to be cleaned (not sure how they could be anyway).
Or do they test for mould etc during inspection?

So is there a worry here? or just an over concerned partner that I can calm down with some facts from you knowledgable lot.
Cheers

 

[Roddy Young]

We have a Vent Axia unit which is very similar and have lived in this house since it was built in 2012. Initially I had similar concerns to you - but not now.

The moist air is sucked up as you said but then expelled through the vents to the outside. It passes through a heat exchanger where it is kept apart from the incoming fresh air.

The net result is that the house itself is very dry but I have found some minor traces of mould in the pipework carrying the outgoing air.

We have lived in houses with much more mould in bathroom areas and around windows and cold walls.

We have none of the moulds, slime, algae one finds in loft header tanks, shower areas and toilet cisterns.

I service our machine myself and remove the heat exchanger annually, take it outside and clean it on a sunny day with water with washing up liquid added. I then rinse it with lots of fresh water.

The fabric filters are 2 original sets which I wash and reuse.

We (pensioners) have never had any health issued that could be related to the Ventilation unit.

Roddy