Extractor Pulling Air from Loft

[leccyblue]

Hi,

I've recently refitted our main bathroom and built an ensuite. In both I've fitted Turbo Tube Pro inline fans to take care of the ventilation. These are being extracted outdoors via the loft and then the soffits. I did some research and found the best I could afford, because a) the ensuite has no external window and b) as I've got older I seem to be very sensitive to mould spores and also have a heightened sense of smell. They do a fantastic job of clearing the moisture when showering, we've had zero mould in either bathroom over the last year and I'm very pleased with the performance of them.

However, more recently we've had new upvc windows and doors and consequently the house is now much better sealed to the outside elements. I'm now noticing that when either fan is running, if I'm stood anywhere in the bungalow where there is an unsealed hole into the loft (e.g. downlighters in hallway, loft hatch, extractor pipework in kitchen etc), I can 'smell' the air that is being dragged out of the loft. This is causing me some discomfort. I realise this sounds a bit soft, but unless you have a heightened sense of smell, it's hard to describe. It's like a mental overwhelm and becomes an unnecessary distraction and focus.

What's the best way to deal with this? Clearly the fans need to be able to pull air from somewhere to do their job, and before we had the windows and doors done, because the old ones were draughty they were able to do this from outside. In the main bathroom I can crack the window open whilst the fan is running but the ensuite has no window. If I seal all the holes into the loft with downlighter lids / foam etc presumably all I will do is reduce the performance of the extractors?

Thanks!

 

[JohnD]

block up the holes in the ceiling.

You can make an open-bottomed box out of plasterboard quite easily, to fit over the light from above, as well as preventing heat and damp rising into the loft, it will block dust and is fireproof.

you can buy readimade hoods if you want.

it is usual for a bathroom extractor to suck replacement air through the gap under the door. This aids stratification of the warm damp air upwards towards the extractor.

 

[foxhole]

Hi,

I've recently refitted our main bathroom and built an ensuite. In both I've fitted Turbo Tube Pro inline fans to take care of the ventilation. These are being extracted outdoors via the loft and then the soffits. I did some research and found the best I could afford, because a) the ensuite has no external window and b) as I've got older I seem to be very sensitive to mould spores and also have a heightened sense of smell. They do a fantastic job of clearing the moisture when showering, we've had zero mould in either bathroom over the last year and I'm very pleased with the performance of them.

However, more recently we've had new upvc windows and doors and consequently the house is now much better sealed to the outside elements. I'm now noticing that when either fan is running, if I'm stood anywhere in the bungalow where there is an unsealed hole into the loft (e.g. downlighters in hallway, loft hatch, extractor pipework in kitchen etc), I can 'smell' the air that is being dragged out of the loft. This is causing me some discomfort. I realise this sounds a bit soft, but unless you have a heightened sense of smell, it's hard to describe. It's like a mental overwhelm and becomes an unnecessary distraction and focus.

What's the best way to deal with this? Clearly the fans need to be able to pull air from somewhere to do their job, and before we had the windows and doors done, because the old ones were draughty they were able to do this from outside. In the main bathroom I can crack the window open whilst the fan is running but the ensuite has no window. If I seal all the holes into the loft with downlighter lids / foam etc presumably all I will do is reduce the performance of the extractors?

Thanks!

Correctly installed the fans remove no air from the loft.

 

[leccyblue]

block up the holes in the ceiling.

You can make an open-bottomed box out of plasterboard quite easily, to fit over the light from above, as well as preventing heat and damp rising into the loft, it will block dust and is fireproof.

you can buy readimade hoods if you want.

it is usual for a bathroom extractor to suck replacement air through the gap under the door. This aids stratification of the warm damp air upwards towards the extractor.

Thanks JohnD. I'm more than happy to go around and seal all of the entry points into the loft. I did this already in the main bathroom on the downlighters because the fan was pulling air via them rather than under the door as you suggest. This worked great. However, I then wonder what the consequence of this will be. The fan will fight harder presumably to extract because air won't be as free flowing?

 

[leccyblue]

Correctly installed the fans remove no air from the loft.

Then I've obviously installed them incorrectly, in that case, because since replacing the windows and doors (which are now air tight) that is exactly what happens. The replacement 'fresh air' that the extractors draw from the path of least resistance when extracting is now via any unsealed openings between the loft and the living areas, e.g. around downlighters, the loft hatch, pipe/cable entry points etc. When either fan is running you can feel it if you hold your hand up to a downlighter, for example.

 

[JohnD]

check the size of the gap under the door.

Usually, the other gaps you mention should be closed to prevent draughts, and heat or water vapour rising into the loft.

Loft insulation is pretty good for muffling draughts, and I recommend the brown variety treated with ecose, which does not shed irritant dust and fibres (it is made by Knauf, but widely sold as an own-brand in the big chains, you will find "ecose" printed on the wrapper)

For small gaps in cailings, I now like the pink expanding foam, which is fire resistant as well. Use a vac then a damp sponge to remove dirt and dust first, the slight dampness helps it to stick and cure. Cover cables or electrical fittings so they do not get foamed.

Round the loft hatch you can tack a batten, or use the door and window type of draught excluder.

these treatments also reduce the passage of noise through gaps

 

[foxhole]

Then I've obviously installed them incorrectly, in that case, because since replacing the windows and doors (which are now air tight) that is exactly what happens. The replacement 'fresh air' that the extractors draw from the path of least resistance when extracting is now via any unsealed openings between the loft and the living areas, e.g. around downlighters, the loft hatch, pipe/cable entry points etc. When either fan is running you can feel it if you hold your hand up to a downlighter, for example.

Doors are never air tight, your windows have trickle vents?