Is this internal vent needed? Trying to resolve (improve) some condensation issues.

[JimDogweed]

Hi. I'm looking for some advice on some internal air vents that I have.

It's an old house (1900/1910) and has a couple of big bay windows. The pictures show 1 example where I seem to get a lot of condensation.

On this example, there is an existing external air brick fitted. Internally, the previous owners have fitted an air vent (I assume to assist with ventilation). The windows here are uPVC sash windows (and therefore no trickle vents).

I've read some conflicting information around vents, so I just wanted some clarification if possible... Should this internal vent be here, and will it be helping with regard to the ventilation or condensation, or could it be making it worse? I have tested this one with a small candle and it seems to be getting some air passing through.

Many thanks.

 

[denso13]

They tended to be for vents for gas back boilers or coal fires etc. Do you have a chimney in use? What heats the room?

 

[JimDogweed]

They tended to be for vents for gas back boilers or coal fires etc. Do you have a chimney in use? What heats the room?

This is our dining room and there's no chimney in use in this room (it's blocked up) - heating comes from a radiator. It's quite a big space though as the wall has been knocked down between this room and the kitchen (the kitchen also has a radiator).

Just trying to understand if it's needed - and doing anything useful with regards to the condensation. It might just be a symptom of an old house with a bay window?

 

[denso13]

Just trying to understand if it's needed

Nothing critical. Could have been for when the chimney was in use.

Block it off and see if it helps. Could be making it worse.

 

[pcaouolte]

Ventilation doesn't usually make condensation worse, but a single air vent might not allow enough air movement to do any good but may just create a draught.

Condensation occurs when warm wet air meets a cold surface. 66% RH is on the high side.

Reducing the moisture content of the air by not drying washing indoors, covering pans when cooking, getting rid of those plants if they are real etc. would help, as would increasing the insulation on the surfaces which are getting the condensation.

 

[JimDogweed]

Ventilation doesn't usually make condensation worse, but a single air vent might not allow enough air movement to do any good but may just create a draught.

Condensation occurs when warm wet air meets a cold surface. 66% RH is on the high side.

Reducing the moisture content of the air by not drying washing indoors, covering pans when cooking, getting rid of those plants if they are real etc. would help, as would increasing the insulation on the surfaces which are getting the condensation.

Thanks.

As long as it doesn't make it worse - that was my main worry, and had read some conflicting info over on the MyBuilder forums about air bricks and vents making it worse?! There doesn't seem to be a notable draught.

But yeah, I try to keep humidity as low as possible with the things you mention - the only thing I haven't thought of is moving the plants. Although afaik some plants (like palms which most of these are) absorb the moisture - could be wrong. I also have a good sized dehumidifier in the next room (the hallway) which is on often and used for when we need to dry clothes in doors.

As for insulation - good shout, but that might be one for the future - it's 100% a cold spot due to the nature of the bay window. Unfortunately, would likely require the wood being ripped off to be able to insulate that lower part. I was considering getting the roof tiles replaced on this bay window in the coming year and had wondered if it would be possible to add insulation at the same time (essentially above the ceiling) - that would probably help. Unfortunately, I don't think the "columns" will be easy to insulate, especially as the windows are only a few years old so won't be getting replaced any time soon.