Pros and Cons - Passive vents in bedroom

[thunt]

I'm social housing tenant and I had a survey from a company called Airtech as we have condensation on the bedroom windows.

Recommendations were to change fans in bathroom and kitchen to ones with a humidistat, and install passive air vents in the 2 bedrooms.

The housing emailed me with the recommendations and asked if i'm happy with the recommendations they will proceed.

I have concerns about the drafts and noise it may bring to the bedroom - layout is we have a mid terrace 2 bed house, 1 bedroom each end with wet-room on the landing.
We only moved here 15 months ago and at the time it had mouldy rotting timber frame windows, which have now been replaced with upvc, central heating system also been upgraded - radiators all new and bigger, new combi boiler. Humidity in bedrooms seem to be around the mid - late 60% even with trickle vents open, and windows slightly ajar.
We use condensor dryer twice a week, don't dry clothes on radiators, keep door closed when showering.

Here's a passive vent on the contractors website so would presume this is what they are wanting to install - http://www.airtechenvironmental.co.uk/product/passive-wall-vent/

Any idea's for pro's and con's or any alternative recommendation i should be counter-proposing?
I did mention a piv unit but that fell on death ears.

TIA

 

[Jadele]

when you say condensation do you mean the windows are beading with water constantly or fogging at shower times? Do you do a lot of cooking with pan lids off? Do the bathroom fans continue running for a while after you trun off the light?

I think I would be tempted to try out the fans first and if this its still an issue then go with the vents.

 

[thunt]

when you say condensation do you mean the windows are beading with water constantly or fogging at shower times? Do you do a lot of cooking with pan lids off? Do the bathroom fans continue running for a while after you trun off the light?

I think I would be tempted to try out the fans first and if this its still an issue then go with the vents.

The windows have condensation on the inside of the windows 'some' evenings / mornings, typically when the outside temp plummets quickly. Never when we've had a shower, not even a slight fog.
And upstairs that is what i cannot get my head around, the surveyor came in with his hygrometer gadget things and didn't seem to take in what i was telling him. I purchased 2 hygrometers and placed them on the window of each bedroom and have been taking readings of outside temp, indoor temp and humidity in each bedroom throughout the day.
For-which the reading prove after a shower the humidity doesn't rise, so i took it from that, showering with the door closed and the fan doing its job, the wet-room isn't the problem.... also the tile grout in the wet-room hasn't discoloured, only sign of condensation in the wet-room is the toilet cistern which is to be expected, but that isn't constant or sever.
The wet-room has an inline ceiling outlet attached to a hose, to a pump in the loft that then blows it out through a vent in the roof, it overruns for 7 mins after switching the light off. Because of this we only turn it off after we have dressed and about to go downstairs, not immediately after a shower.

Re: the kitchen, we rarely have pan lids off, just when cooking with a sauce that requires stirring, or grilling. We use a steamer but that's with a lid on, and whenever cooking we have an extractor fan on and window open, also kitchen door remains shut.

We really are 'behaving' best we can to reduce condensation, but here's a photo of the worse we've had last week and thinking we're not in to winter yet so will only get worse if something isn't done, but still don't see how humidistat fans in kitchen and wet-room, with the way we keep doors shut, etc is going to improve the situation in the bedrooms.

 

[JohnD]

try running the fan for longer. that's all the humidstat will do. I don't know the rating of your inline fan, but it looks like quite a powerful one.

I gather you use the trickle-vents on the bedroom window, and are opening it a bit each morning when you get up.

Apart from moisture in the bedroom from breathing and perspiration, water vapour is lighter than air so will rise up through the house.

Look out for any signs of leaks, for example under radiators or sink.

 

[thunt]

try running the fan for longer. that's all the humidstat will do. I don't know the rating of your inline fan, but it looks like quite a powerful one.

I gather you use the trickle-vents on the bedroom window, and are opening it a bit each morning when you get up.

Apart from moisture in the bedroom from breathing and perspiration, water vapour is lighter than air so will rise up through the house.

Look out for any signs of leaks, for example under radiators or sink.

Thanks for your reply,

I think the fan does a great job in the wet-room, it certainly clears steam from the mirror very quickly.
The reason i took a photo of the pump was to see if i could increase the running time. It looks like you can but means opening it up which i'm not prepared to do.
I mentioned this to the housing, but as per the piv unit, fell on deaf ears.

Yes all trickle vents are open, and condensation appears most on the middle of the 3 panes as the middle doesn't have a trickle vent.
Both outside panes of the windows are open ajar.
All radiators are new, and have just checked the boiler and the pressure hasn't dropped, but will go around double checking for leaks, thank you

 

[Jadele]

do you keep you house cold overnight? or indeed through the day. That last pic is bad for double glazing. The RH shown is also very high. bringing up the indoor temp to 22 would cut that RH a lot. if you ware not getting condensation elsewhere it maybe that having the vent and windows open and presumably curtains closed creates a dead air cold spot in the window recess and all the moisture drops out of the air as it cools behind the curtain

 

[John D v2.0]

Bringing up the temperature reduces the Relative humidity but not the dew point, so if the windows are badly insulated it will still get condensation.
I agree that 86% is very high, and suggests that damp air wasn't ventilated promptly from some origin.

How do condensing dryers work? Could that be leaking humidity into the room? Once we rented a house with a condenser dryer, and we had terrible mould in the adjacent single skin bathroom (rear of an old terrace)
Eventually it turned out it was actually a standard dryer with no vent hose attached.

 

[thunt]

do you keep you house cold overnight? or indeed through the day. That last pic is bad for double glazing. The RH shown is also very high. bringing up the indoor temp to 22 would cut that RH a lot. if you ware not getting condensation elsewhere it maybe that having the vent and windows open and presumably curtains closed creates a dead air cold spot in the window recess and all the moisture drops out of the air as it cools behind the curtain

The thermostat is placed in the hallway and is set at 21c constant and never turned off, although the display hasn't gone below this, i,e hallway temp above 21c so heating not come on. There are instances like this morning when it felt colder, thermostat showed 21.5c, so i turned it up to 22c for a couple of hours, just so the radiators would kick in and warm the place up.
This has me thinking, could the thermostat be faulty and showing a higher temp then it actually is... i'll place a thermometer next to it and see how it compares. Thanks for initiating that train of thought, if not only to rule that out.

I'm hesitant in raising the temp to 22c as we find it warm enough at 21c, my wife and i have disabilities which means we are home a lot of the time so will see if the thermostat is correct first before considering that.

Thanks

 

[thunt]

Bringing up the temperature reduces the Relative humidity but not the dew point, so if the windows are badly insulated it will still get condensation.
I agree that 86% is very high, and suggests that damp air wasn't ventilated promptly from some origin.

How do condensing dryers work? Could that be leaking humidity into the room? Once we rented a house with a condenser dryer, and we had terrible mould in the adjacent single skin bathroom (rear of an old terrace)
Eventually it turned out it was actually a standard dryer with no vent hose attached.

Not sure how they work, but it is a brand new model, which we ensure all filters are cleaned out after each use.
We use it half a day, twice a week, and when we do, we open the windows wider.

Yes the humidity reading rises, but after a couple of hours goes back down to where it was.

When we moved in, we decorated top to bottom, the tenants before us smoked in every room it seemed, and we do not. So when it came to decorating i primed all the walls first with a cover stain. The walls have shown no signs of damp or mould, and are dry to touch.

 

[Jadele]

Raising the temp will increase the due point temp if RH was fixed t's not so the increased temp means a lower RH which drastically lowers the due point. all in the warmer room creates a lower RH, warmer glass and a lower due point that the glass temp must hit to get the condensation.

I think you may have something about the condenser dryer they are definitely not 100%efficient and must be throwing out very humid air.

 

[Jadele]

its 21 in the hall but only 19 in the bedroom and probably even colder when curtains are closed.

 

[John D v2.0]

Raising the temp will increase the due point temp but more importantly the increased temp means a lower RH which drastically lowers the due point. all in the warmer room creates a lower RH, warmer glass and a lower due point that the glass temp must hit to get the condensation.
.

From standard physics, Raising the temperature won't affect the dew point at all, as simply changing the temperature of given air doesn't affect how much water is in the air. The relative humidity only goes down because the air can hold more moisture at higher temperature.
I agree that the glass is likely to be warmer though, hence why I applied my comment to a badly insulated window. A well insulated window would get less condensation, but not due to any change in the dew point or relative humidity.

 

[Jadele]

but when the RH is lower the due point is lower. increased temp lower RH, lower due point temp

 

[John D v2.0]

but when the RH is lower at the same temperature the due point is lower. increased temp lower RH, lower same due point temp

Fixed that for you. Where do you think the water in the air went when you increased the temperature?

 

[Jadele]

Fixed that for you. Where do you think the water in the air went when you increased the temperature?

ok you think that then