Condensation & Room Vents blocked inside

pan wrote: »

Hi all,

I'm in fairly new house (8 yrs) but I'm noticing alot of condensation on the window(double glazed) in some rooms. All rooms have vents but only some can you feel some air passing though them. Is there a recommended size hole? I've looked in one or two of them they seem to be parially blocked by insulation.
Should you for example be able to see out through the vent hole?

Vents in my house have a 100mm wavin pipe going through, so I can see some light. Some of your vents may be totally blocked, check the outside grill is actually over the hole and not just cosmetically stuck to the render (not unheard of).
If you can't feel airflow you could check it by holding a lit candle to the vent and seeing if the flame is drawn to one direction, in or out doesn't matter.

pan wrote: »

On the condensation front, I heard double glazing should reduce this because indoor part of glass should be warmer than external glass and therefore result in no condensation? Is this true and if so is this a sign the double glazing is not working correctly?

Thanks in advance
Pan

Although the inner pane is warmer you will still get condensation if the conditions are suitable, for example I often notice condensation on cold mornings. So long as the condensation is not between the panes then the double glazing unit is ok.

I think you need to focus on keeping the vents clear and reducing your sources of moisture e.g. keep bathrooms door closed after showers, open kitchen windows when cooking/washing floor, don't dry clothes indoors, etc.