Should I suck or should I blow??

[theflyingpig]

I have a room with a supended floor in a corner of the house that is subterranean. The public highway outside, built up higher and higher over the years, prevents me from lowering the outside ground levels.

It is therefore difficult to ventilate the sub floor. I have so far put in some periscope cents, but these are proving inadequate.

Luckily there is a disused fireplace in the room, with the chimney stack terminating in the loft. This is going to allow me to run a duct from the subfloor into the loft.

But, should I use a PIV unit to blow air into subfloor, or an extractor to suck air from it?

Anyone? Thanks!

 

[JohnD]

Suck

Though the damp air will tend to rise naturally up the chimney, provided you put fresh air inlets into the void.

 

[theflyingpig]

Thanks. I think I'll put an extraction duct down the chimney, and leave to open to the void for some natural ventilation.... As in, block the chimney off to the room itself, but open it to the subfloor....

Now, which extractor? It will need to run nearly constantly, and the duct will be somewhere around 8 metres long....

 

[JohnD]

Solar & Palau (also sold under the Envirovent brand) offer extractors with a ball-bearing motor on anti-vibration rubber mountings, which I find have a long life and are very quiet.

Try it on natural airflow first, you might not need a fan.