# Replacing hole in the wall air vents with humidity sensitive air inlets



## Prosper (2 Dec 2020)

Anyone ever upgrade the very basic hole in the wall air inlets with something more modern and efficient? For example one of these? If so then how easy was it to do?








						EHT - Air inlets - Aereco
					

Installed on the wall or on a rolling shutter casing, the EHT humidity sensitive air inlet is the ideal choice for air admission through the wall, and thus provides an alternative where lack of available space (on window frames) prevents the installation of window mounted air inlets.




					www.aereco.ie


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## Alkers86 (2 Dec 2020)

We have those vents fitted, they are a straight swap for the normal hit and miss vents once you order the correct size for the core you already have in your wall. They're very easy to install if the core is already drilled.

In order for these vents to function as intended you need to have continuously operating extract vents in wet rooms (kitchens and bathrooms). These should be humidity controlled also so they are only extracting a low air flow most of the time but when high humidity is detected, they will increase the fan speed. This causes fresh air to be drawn in through the Aererco wall vents. You're also supposed to ensure a 2cm air gap underneath internal doors to facilitate air flow between rooms. For this to be effective, you need to have a reasonably airtight house or the extract fans will just cause air to be drawn in through other areas. In the absence of these extract fans, the aerecco units are not likely to provide sufficient ventilation


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## Blackrock1 (2 Dec 2020)

do these need power?

we have an a3 rated house with this ridiculous hit and miss vents i wouldnt mind replacing them,

also can these be painted?


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## Prosper (2 Dec 2020)

Alkers86 said:


> In order for these vents to function as intended you need to have continuously operating extract vents in wet rooms (kitchens and bathrooms). These should be humidity controlled also so they are only extracting a low air flow most of the time but when high humidity is detected, they will increase the fan speed. This causes fresh air to be drawn in through the Aererco wall vents. You're also supposed to ensure a 2cm air gap underneath internal doors to facilitate air flow between rooms. For this to be effective, you need to have a reasonably airtight house or the extract fans will just cause air to be drawn in through other areas. In the absence of these extract fans, the aerecco units are not likely to provide sufficient ventilation


Thanks for that Alkers86. My house is a 1980's build and I've done a fair bit of diy work (plugging draughts, adding more attic insulation etc.) plus installing double glaze windows throughout but it would not be considered "airtight" compared to modern build standards. I do have extractor fans in bathroom (no window to outside) and kitchen but I'm not sure what you mean by "continuously operating"?  From what you say it appears that the Aereco units don't suit. I'm looking for something just a bit better than the existing plastic grille covering a hole in the wall so that when you slide over the cover to close it there's no draught.


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## Leo (3 Dec 2020)

Prosper said:


> I'm looking for something just a bit better than the existing plastic grille covering a hole in the wall so that when you slide over the cover to close it there's no draught.



If you have 5" cores you could install an anti-draught vent. These will reduce the effective free area, so you'll need to check you have sufficient ventilation for the space. 

Also, don't rely solely on humidity to determine when to allow ventilation, allowing oxygen in and carbon dioxide out is important too!


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## Prosper (3 Dec 2020)

Thanks Leo, that looks more like what I want. Tbh I wasn't thinking of humidity at all, just preventing draughts when the air vents are in closed position. I leave them open I'd say 95% of the time at least. It's just at the coldest and windiest times that I close over the grille.


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## Leo (3 Dec 2020)

Prosper said:


> Thanks Leo, that looks more like what I want. Tbh I wasn't thinking of humidity at all, just preventing draughts when the air vents are in closed position. I leave them open I'd say 95% of the time at least. It's just at the coldest and windiest times that I close over the grille.



I put one of those in my parents house when they needed a new gas hob. Gas installer couldn't proceed without a permanently open vent. He was happy with that and my parents have never complained to me about it which tells me they never notice a draught, and my mother REALLY feels the cold!


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## Prosper (3 Dec 2020)

Blackrock1 said:


> also can these be painted?



I'm sure they can. If you want to change the colour just apply a good adhesive primer like Stix and then paint the colour you want as a topcoat.


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## Alkers86 (3 Dec 2020)

Blackrock1 said:


> do these need power?
> 
> we have an a3 rated house with this ridiculous hit and miss vents i wouldnt mind replacing them,
> 
> also can these be painted?


They don't need power


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## Alkers86 (3 Dec 2020)

Prosper said:


> Thanks for that Alkers86. My house is a 1980's build and I've done a fair bit of diy work (plugging draughts, adding more attic insulation etc.) plus installing double glaze windows throughout but it would not be considered "airtight" compared to modern build standards. I do have extractor fans in bathroom (no window to outside) and kitchen but I'm not sure what you mean by "continuously operating"?  From what you say it appears that the Aereco units don't suit. I'm looking for something just a bit better than the existing plastic grille covering a hole in the wall so that when you slide over the cover to close it there's no draught.


Continuously operating as in the extractor fans need to be running slowly to encourage airflow in the house. They do this silently but speed up whenever there is high humidity. Without the extractors running, you'd get very little airflow in through the aereco units.

The unit linked above by Leo has a free area of 30cm2, this is less than even the aereco units which have 40cm2. I'm not sure that this will provide sufficient airflow as a standalone device.


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## Prosper (3 Dec 2020)

Alkers86 said:


> Continuously operating as in the extractor fans need to be running slowly to encourage airflow in the house. They do this silently but speed up whenever there is high humidity. Without the extractors running, you'd get very little airflow in through the aereco units.


I never knew about continuously running extractor fans. Earlier this year I installed new extractors in my kitchen and bathroom so I'm not going to change them now. I live in a small two bed townhouse so I think the type that Leo has mentioned will be sufficient to install in an 11mtr2 bedroom.


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## Leo (3 Dec 2020)

Prosper said:


> I live in a small two bed townhouse so I think the type that Leo has mentioned will be sufficient to install in an 11mtr2 bedroom.



Just to note that the standards (p24) for rental property demand a minimum 65sq cm free area!


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## Prosper (4 Dec 2020)

Leo said:


> Just to note that the standards (p24) for rental property demand a minimum 65sq cm free area!


How exactly is the free area calculated?


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## Leo (7 Dec 2020)

Prosper said:


> How exactly is the free area calculated?



Is the combined area of the most restrictive part of the vent assembly, it's usually listed in the spec details for a vent. For a straight through vent with a hit/miss cover, it would be the total area of all the little holes on the internal cover.


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## Prosper (7 Dec 2020)

Leo said:


> rental property demand a minimum 65sq cm free area!


I think I'll get this one as it has a quoted free area of 100sqcm. It should just about fit.
[broken link removed]


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## Alkers86 (8 Dec 2020)

Leo said:


> Just to note that the standards (p24) for rental property demand a minimum 65sq cm free area!


I assume this is for passive ventilation only, the aereco units get aware with the lower amount as they require the constantly running extractors as explained above


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## Leo (8 Dec 2020)

Alkers86 said:


> I assume this is for passive ventilation only, the aereco units get aware with the lower amount as they require the constantly running extractors as explained above



The link has the details, believe it or not the regs make no reference to active Vs passive!!


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## Prosper (9 Dec 2020)

Alkers86 said:


> the aereco units get away with the lower amount as they require the constantly running extractors as explained above





Leo said:


> believe it or not the regs make no reference to active Vs passive!!


I don't know for sure but I think Alkers assumption is a logical and reasonable one.  Also, as he said in his reply to my original post you'd need to have a reasonably airtight house with airgaps at the bottom of all internal doors. If I was going for a deep retrofit then I'd install the Aereco vents along with continuously operating air extraction fans in bathroom and kitchen. But I'm not doing that, so I won't install them. However, thanks to both of you I've learned something about the importance of airflow in a house and as a result I'm removing the "brushes" I attached to the bottom of the internal doors.


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## Leo (9 Dec 2020)

Prosper said:


> I don't know for sure but I think Alkers assumption is a logical and reasonable one.



Oh, he absolutely does. A decent mechanical ventilation system will be far superior to open holes in every room. The fans will enable sufficient change of air through smaller holes with or without heat recovery. 

My personal thoughts are that some elements of the standards for rental properties are a very blunt instrument, particularly in the hands of some of the LA inspectors who occasionally inspect rental properties (more common if the tenants are availing of HAP). I've seen them insist on open vents be added to rooms in a '50s ex-corpo house that was as far from air-tight as you can get.


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