# To vent or not to vent ..



## f0zzy (16 Oct 2008)

We have a newish (couple of years) build, heavily insulated house. Problem is it appears to be too well insulated as we seem to have a condensation/damp issue. House was built with trickle vents in the windows.

A builder has advised these are next best thing to useless. Suggestion is to install traditional hole in the wall vents. My experience with these however is not positive, due to heat loss, drafts etc and have heard most people just block these up anyhow.

HRV is one option .. but an expensive one .. 

Anyone know of other options ?


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## aircobra19 (16 Oct 2008)

Maybe a dehumidifier? No exactly green, but...


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## Towger (16 Oct 2008)

Heat recovery system.


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## theoneill (16 Oct 2008)

When we moved into our new house there was heaviness in the air in the living room, it was always warm but it felt damp. It turned out that our chimney was blocked and as soon as it was removed the room had proper air circulation. I’m not sold on making my home airtight. Yes it may make the house warmer and retain more heat but IMO a home needs air circulation to keep the house and its inhabitants healthy. Having said that I still open to convincing.


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## sydthebeat (16 Oct 2008)

firstly you need a survey from a competent person to confirm the exact cause of the condensation, this would be very important in determining where you go from here.

a solution can then be drawn up that suits all the factors ie cost, existing construction, dwelling type (2 storey?) nuisance threshold, etc

its possible that a passive stack system could be installed into the most effected rooms.

it would be a shame to have a well insulated dwelling peppered with holes.

perhaps the solution could also be to have a strict schedule of 'window opening' times!!


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## sydthebeat (16 Oct 2008)

theoneill said:


> When we moved into our new house there was heaviness in the air in the living room, it was always warm but it felt damp. It turned out that our chimney was blocked and as soon as it was removed the room had proper air circulation. I’m not sold on making my home airtight. Yes it may make the house warmer and retain more heat but IMO a home needs air circulation to keep the house and its inhabitants healthy. Having said that I still open to convincing.


 
theres a difference between 'controlled' or 'designed' ventilation and 'uncontrolled' ventilation. An open fire should NOT be considered 'designed' ventilation.....

if there was no air vent in your living room, a pre purchase survey should have clled this up, and the matter should have been dealt with before purchase.


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## theoneill (16 Oct 2008)

Sorry, there was a vent in the living room but it turned out that one of the builders accidentally dropped a bag of cement down our chimney. It's just that the difference in the air quality was amazing


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## sydthebeat (16 Oct 2008)

theoneill said:


> Sorry, there was a vent in the living room but it turned out that one of *the builders accidentally dropped a bag of cement down our chimney*. It's just that the difference in the air quality was amazing


 

sorry for laughing, but thats classic....


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## theoneill (16 Oct 2008)

Not as funny as our faces when the cement came tumbling down into our living room


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## sydthebeat (16 Oct 2008)

theoneill said:


> Not as funny as our faces when the cement came tumbling down into our living room




i hope you gave them an ear full!!


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## f0zzy (16 Oct 2008)

Thanks for replies. To answer a few points here.

Controlled ventilation. Yes each morning and afternoon windows are opened and house is vented.

We've had qualified plumber on board checking pipes etc for leaks.

We use dehumidifier when condensation/air heaviness is very bad but this
is not a long term solution hence why we have a builder involved now.

Heating is something we're also concerned about and hence we dont want to create a heat problem by fixing the vent issue.

HRS/HRV is an option but its an expensive one which has why I was hoping there is some other technology other than trickle vents that work and dont require blowing a hole in the wall of each room.


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## aircobra19 (16 Oct 2008)

Towger said:


> Heat recovery system.



What is that?


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## f0zzy (16 Oct 2008)

aircobra19 said:


> What is that?



http://en.wikipedia.org/wiki/Heat_recovery_ventilation


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## Simeon (16 Oct 2008)

sydthebeat said:


> i hope you gave them an ear full!!


Of cement?


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## sfag (17 Oct 2008)

f0zzy said:


> A builder has advised these are next best thing to useless. Suggestion is to install traditional hole in the wall vents. My experience with these however is not positive, due to heat loss, drafts etc and have heard most people just block these up anyhow.
> 
> Anyone know of other options ?


 
I have vents up high on the walls. There is no heat loss or drafts. Reconsider.


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## aircobra19 (17 Oct 2008)

sfag said:


> I have vents up high on the walls. There is no heat loss or drafts. Reconsider.



Can you explain how that works please.


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## sydthebeat (17 Oct 2008)

aircobra19 said:


> Can you explain how that works please.


 
sfag is talking rubbish aircobra.

typical wall vents are designed to allow generally 4 air changes every hour. 

so picture this, you have a room with a rad and an air vent. 
the air is completely changed 4 times every hour in the room by the vent, therefore the radiator has to heat the whol eroom 4 times every hour. thats how it works.

with a heat recovery unit working at say, 75% efficiency,  and assuming the same room... then....
the rad heats the room once, during the next hour the HRv system change sthe air 4 times, as like the passive vent, however, every time it changes the air it retains 75% of the heat of the room. therefore with HRV systems the room only needs to be heated once every hour instead of 4 times with a passive vent. thats the principle its based on and the reason they are relatively expensive pieces of machimnery (approx 5k for a standard house)


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## aircobra19 (17 Oct 2008)

I never heard of them before tbh. I understand that some ventilation is usually a good thing, for chimneys and rooms in general. Then of course you have open vents if you have gas etc. What do you with them?

Incidentally can you get vents for bathrooms, with a electric fan that actually seal when no in use? I've WC which is pretty exposed corner of the house and I think that its a major draught problem. I was thinking of putting a cowl on it, but it there another option?


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## sydthebeat (17 Oct 2008)

aircobra19 said:


> I never heard of them before tbh. I understand that some ventilation is usually a good thing, for chimneys and rooms in general. Then of course you have open vents if you have gas etc. What do you with them?
> 
> Incidentally can you get vents for bathrooms, with a electric fan that actually seal when no in use? I've WC which is pretty exposed corner of the house and I think that its a major draught problem. I was thinking of putting a cowl on it, but it there another option?


 
aircobra, theres two type of necessary ventilation ... 'background' ventilation that feeds fresh air constantly... and 'purge' or 'rapid' ventilation that allows for fast exhausting of water vapour, smells etc.

both are necessary for health reasons 

make sure that any work you carry out complies at least to current building regulations


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## wexford dude (20 Oct 2008)

If you only have the problem in one room you may consider the Passivent system.I am not affiliated but am trying it out on a colleagues house.You would need the standard wall vent opening (100mm dia) and then you basically insert the vent you choose from Passivent.The problem with standard wall vents is that they don't always draw air - I think it depends on wind direction.


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## pullandbang (21 Oct 2008)

sfag said:


> I have vents up high on the walls. There is no heat loss or drafts. Reconsider.


 
Lucky you..........ours produce howling gales in the rooms. I put covers with sliding grills on mine and close them when there is a breeze.


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## Aimee (6 Nov 2008)

pullandbang said:


> Lucky you..........ours produce howling gales in the rooms. I put covers with sliding grills on mine and close them when there is a breeze.


 
PAB - where did you manage to get the covers with the sliding grills ????   I need them badly before we are blown out of it    I have this thing in my head that they changed building regs to ensure these vents were left open at all time and thought perhaps thats why they got rid of the covers with the sliding grills (??!!)  - I could only find open covers when I went looking, would love to find the open/close covers!!!


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## Dreamerb (6 Nov 2008)

Aimee said:


> PAB - where did you manage to get the covers with the sliding grills ???? I need them badly before we are blown out of it  I have this thing in my head that they changed building regs to ensure these vents were left open at all time and thought perhaps thats why they got rid of the covers with the sliding grills (??!!) - I could only find open covers when I went looking, would love to find the open/close covers!!!


You must have a fixed vent in a room with a gas / oil burning appliance (unless it's fully separately vented and enclosed), or anything liable to produce substantial carbon monoxide - so presumably for any type of non-electric stove, and possibly for an open fire too. 

I think the sliding vents are okay in other rooms, and you can get those vent covers in plenty or normal home supplies and DIY outlets. We got some in either Atlantic or Homebase.


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## Aimee (6 Nov 2008)

Dreamerb said:


> You must have a fixed vent in a room with a gas / oil burning appliance (unless it's fully separately vented and enclosed), or anything liable to produce substantial carbon monoxide - so presumably for any type of non-electric stove, and possibly for an open fire too.
> 
> I think the sliding vents are okay in other rooms, and you can get those vent covers in plenty or normal home supplies and DIY outlets. We got some in either Atlantic or Homebase.


 

Thank you Dreamerb - I need one badly for our ensuite and bathroom - unfortunately we live "high up" and experience severe winds - we could really do with being able to close these vents on specific days when it is v windy - I didn't want to close them off completely - good to know I can get the sliding vents - I will go in search!

Thanks again!


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## aircobra19 (6 Nov 2008)

I always wonder about these vents. I seen some which are simply a square hole in the wall with a grill on either side. The problem with this is that the air can go straight through, especially on an exposed wall creating massive draughts and heat loss. I've seen heavy rain get through them aswell. I thought they had to be offset to prevent this but maybe I'm mistaken. The other problem with this is that the wind and rain, actually gets into the wall space. If you run your hands on the wall around the vent you can feel how cold it is. Which can't be right. 

I think they should be replaced with something along these lines...I don't know if how they fit with the building or saefty regulations, you'd need to check that out. 

[broken link removed]
[broken link removed]

seals the wall space and stops draughts and rain from getting in. On a powered extractor vent there should be a back draught protection flap or some means of preventing air from coming in when the fan is not one. Most I've seen in Ireland don't have these either.


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## ospreymate (7 Nov 2008)

Hi f0zzy,
I hope I can be of some help.. The first thing to try, is to stop the build up of humidity (water vapour) in the first place. Install mechanical extractor fans in your Kitchen, Utility Room, Bathroom and En-Suite, in the last two preferable with 15-30 Min overruns. Run a small amount of cold water first in your bath before adding the hot. Some windows in addition to having trickle vents can be left slightly opened in a locked position. Don’t dry clothes inside. Check your radiators and hot water supply for any leaks, indeed any water pipes supply or waste? Insure your Tumble Dryer is properly plumbed. Don’t leave Bedroom Doors open during the day especially if there is no heating on in them, and you have cooking or washing going on elsewhere.

I agree with You we spend a fortune Insulating our houses and heating them and then we have to go and put “Holes in the Walls” to ventilate the house. These “holes in the walls” are compulsorily under current Building Codes. Their surely must be a better way? 

An earlier post on “Ask about money .com” touched on a similar topic 
http://www.askaboutmoney.com/showthread.php?t=16903

Quinno‘s Reply on the 21-01-2006, 10:16 am- the second last post, is a comprehensive and informative reply and explains the need for these “hole in the wall” vents.

I know these “hole in the Wall” air vents are draughty but they are a _requirement _under current Building Regulations in so far as :- they are a means of achieving this requirement under the Technical Guidance Documents (TGD)- Quinno explains this very well. Now (TGD) Part F deals with Ventilation & (TGD) Part J deals with Heat Producing Appliances. 

Basically in Part F it states that.. a Habitable Room (which may be taken as a bedroom or Living Room should have a ventilation opening (background) of 6500mm² ( 81mm x 81mm or 91mm Ø) AND an opening (window or door) for rapid ventilation of not less than 1/20th of the Floor Area. In a Kitchen & Utility Rooms a ventilation opening (background) of 6500mm². AND A suitable opening 1/20th of the Floor Area .. AND a Mechanical Extract Ventilation) ie a Fan. or Passive Stack Ventilation (PSV) .. Bathrooms and WCs requirements are somewhat similar to Kitchens.. But there are - if, buts & ands …

In Part J ..An room with a cooker should have an open-able window or if it is a small room a permanent ventilation opening at least 5000mm². A room that contains an open-flue appliance (Fire Place – Solid Fuel – Range, Stove etc.) should have a permanent ventilation opening at least 150mm² for each kW of appliance input rating, but never less than 6500mm²

Now the above is as I see it??? There may be further requirements?? You can see basically the requirements for all these “Holes in the Wall” ?

I am currently Building a “New House” and I’m not if favour of these “Holes in the Walls” and a looking for suitable Alternatives. But I don’t know all the answers and have many Questions of my own.

If you install a gas Range with a balanced flue do you need a Permanent Wall Vent. (PWV)…

If you install a Baxti Burnall Fireplace (this has its own Air Supply under floor) do you need a PWV? http://www.c20fires.co.uk/fireplace_accessories/burnall.htm
Does any know where I can get a Stove with its own air supply? (From a duct plumbed to the outside)

Can the PWV have shutters and can it be closed if the Fire say is not lit? I know an open flue is a very effective fresh air intake.and most of the heat goes up the chimney when it is (70%)! Check out the “Air Flow Stoves”. http://www.airflowstoves.ie Air Flow Stoves can supply two alternative methods of heating to the conventional oil and gas systems. The first ‘The French System’ this method pipes hot air around your house. The second ‘The German System’ where the energy is absorbed by the core of the fire place and slowly releases it as radiant heat over a 12-24 hour period.

Here is a nifty idea.. http://www.darco.com.pl/eng/oferta.php?o=1&kid=6&xid=0&pid=565
AN Air intake set with a heater that provides fresh air to the building and warms it up.

OR .How about this one http://www.allvent.com/product_a30.html from an Irish company?

As f0zzy said “”HRV is one option .. but an expensive one ..””


Check Out This Site ..
http://oikos.com/esb/39/VentOpt.html

Its seems pointless fitting Insulating (under floor, in walls, in ceilings, in attic etc.) , Fitting double glazing with E glass, stopping thermal bridging around doors windows floors etc, Sealing around draughty fitting !. Recess front Porches. Lagging hot pipes, Everything to make our homes Warm ( all above now Regulations) And the same Regulations then say you have to put a big 4” Ø hole or two, in all your walls to let the cold wind blow in..

Any Body with and Ideas ????


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## sydthebeat (7 Nov 2008)

ospreymate said:


> Any Body with and Ideas ????


 
HRV systems...

these will become the standard by 2010... passive vents will be seen as a backward method of ventilation...

there is a new draft TGD F that deals with these...

unless someone can come up with an method of passively recovering heat in ventilation systems, then mechnical HRV systems are the way forward...


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## bren1916 (7 Nov 2008)

I've had similar problems with draughts - in bedrooms/living room etc I got the internal sliding covers which keep 90% of draught out so still getting a small bit of ventilation even when closed in winter!
For my extractors in kitchen and bathrooms I finally sourced backdraught dampers in Ireland which fit in between the inner and outer covers (cavity) and come in various diameters.They work a treat as the force of the extracted air opens the damper but it cannot be opened from wind/draughts from the outside.
Sliding Grills from Kingstons Hardware Pembroke St and Dampers from www.ventac.com


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## ospreymate (11 Dec 2008)

sydthebeat said:


> HRV systems...
> 
> ...


 

As f0zzy said “”HRV is one option .. but an expensive one ..””


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## Aidomoss (13 Dec 2008)

This might be of use to some. Not sure how it fits in the house, probably in the wall, but it might sort out the heat loss problem with standard vents!!!! I haven't used this myself but it might be worth a go!!!!!


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## sfag (13 Dec 2008)

sydthebeat said:


> sfag is talking rubbish aircobra.
> 
> typical wall vents are designed to allow generally 4 air changes every hour.
> 
> ...


 


"The air is changed every 4 hours" - How can this be?. 

Heres a real life experiment for you.
Every summer my heating is switched off. 
Lets say the tempature drops outside to say 10 degress.
The tempature in my vented bedroom room will stay at 20 degrees - without heating - all night. 

If the air inside the room is replaced every 1/4 of an hour the room tempature should be the same as outside. It is not - it never is - in fact it never cools. 

Regarding draughts from holes in walls there is only ever fierce draughts if the wind blows from the direction on which the vent is placed and you can always flip shut the vent cover on the inside anyway - and still let some air in. 

The wind blows most often from a southerly direction . Dont place your vents on these walls.


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## aircobra19 (13 Dec 2008)

sfag said:


> ...Lets say the tempature drops outside to say 10 degress.
> The tempature in my vented bedroom room will stay at 20 degrees - without heating - all night. ....


 
Do you live in Spain or something?


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## sfag (15 Dec 2008)

No - Louth. 
My vented upstairs bedrooms - hole in the wall vents -  rarely drop below 18 degrees even on the coldest winter day with the bed room heating off. Insulated with 60 mil cavity insualtion. Thats it. I can tell because all rooms have thermostats on the walls. 

As regards the  wind. Almost always from the south. The next 14 days:



No vents on the south side = no draughts. 

Hows that for a low tech solution.


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## AlbacoreA (15 Dec 2008)

Bit hard to believe that a room will stay at the temp temperature all night on a freezing cold night with no heat. Unless its getting heat from other rooms, like the one beneath it. Even with no vents at all.


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## sfag (16 Dec 2008)

My house is a modern build. 
I guess the heat rises a bit - but not much. The floors have insulation so not too much should get up. I
It has very large windows with light blinds - not condusive to keeping the heat in. 
I guess the wife is hot. Have to say the kids give off a lot of heat too while they sleep. 
Its a three storey house. The top floor is under used and does not have the heating on all. It stays at 18 - 19 degrees. 
I consider that bloody cold but others on these boards switch their heat off when it hits 18 degrees.

And last but not least every room in the house has hole in the wall vents letting air in and out.


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## gooner (16 Dec 2008)

sfag said:


> My house is a modern build.
> I guess the heat rises a bit - but not much. The floors have insulation so not too much should get up. I
> It has very large windows with light blinds - not condusive to keeping the heat in.
> I guess the wife is hot. Have to say the kids give off a lot of heat too while they sleep.
> ...


 

I think you have built yourself a passive house without knowing it,nice one.


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## extopia (16 Dec 2008)

Yes, if the temperature is warmer than outside with no heating, then the vents are not working, simple as that.


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## MacTheKnife1 (16 Dec 2008)

sfag said:


> No vents on the south side = no draughts.
> 
> Hows that for a low tech solution.



So put them on the north side instead?? Just wait for one of those freezing northerlies and your ass is frozen.

Here in the west of ireland the wind comes from all directions, but South Westerlies are most prevalent.

I suspect your missus is heating the house while you are away and turning it off when she expects you home. Either that or you have a severe radon problem and the radioactivity is heating your house. Or perhaps its a goddam miracle.


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## sydthebeat (16 Dec 2008)

sfag, you probably didnt realis ethis but most draughts are formed when the wids blows parallel with the wall... not directly at it.

try blowing into a bottle.... blowing directly at it makes no effect on the inside... 

its called 'positive and negative pressure'.....


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## sfag (18 Dec 2008)

The theorys are interesting. I'm just quoting my objective experience. Air is good. Let it in.


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## Aodhán (15 Apr 2019)

A google on vents, draughts, wind, cold, new house brought me to this thread.

This is truly awful. I put over €150k into gutting and refurbishing this house in the past two years and the BER is now B1. It's a lovely, cosy house where the heat is rarely needed, and I've put the fire - an inset stove - on once since we moved in a year ago (and that was just to test it).
However, the vents on these windy days are intolerable. The place is freezing with wind coming from everywhere. In the sittingroom, where the fire is and we therefore have those permanently open vents it is awful given all the money we spent wrapping the whole house up. There's no sense to it.  For the record, I strongly suspect that, despite what every "expert" told us, we did _not_ need permanent wall vents here as our Stovax Studio 500 inset stove had in-built vents. But, just in case, everybody covers themselves by saying "You need vents". Also, if we got vents built into our windows, would that have negated the need for these barely covered  massive holes in the walls?

The bedrooms, however, are infinitely worse. The plastic flip vents are in every room outside the sittingroom. But they are hopeless as the wind comes straight through them. They do not seal when they are shut. You wake up with sore throats and colds after a few days. Instead of being able to let the air in when we leave the house during the day, these windy days with these vents mean there's constant wind going through the house night and day.

I accept that carbon monoxide, for which we have alarms across the house, is a serious problem. However, surely it does not necessitate this much, eh, "ventilation" in the house? Would anybody have a safe solution to this currently unsatisfactory situation? Thanks.


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## AlbacoreA (15 Apr 2019)

Get vents with baffles or at least with a cowl.

If the wind hits the house directly with no shelter from trees or other houses/buildings it comes straight through.


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## Leo (15 Apr 2019)

Aodhán said:


> I strongly suspect that, despite what every "expert" told us, we did _not_ need permanent wall vents here as our Stovax Studio 500 inset stove had in-built vents.



No, the regs demand additional ventilation. They're online so you can verify what your experts have told you.



Aodhán said:


> Also, if we got vents built into our windows, would that have negated the need for these barely covered  massive holes in the walls?



Unlikely to offer sufficient ventilation. 

The bedrooms, however, are infinitely worse. The plastic flip vents are in every room outside the sittingroom. But they are hopeless as the wind comes straight through them. They do not seal when they are shut. You wake up with sore throats and colds after a few days. Instead of being able to let the air in when we leave the house during the day, these windy days with these vents mean there's constant wind going through the house night and day.



Aodhán said:


> I accept that carbon monoxide, for which we have alarms across the house, is a serious problem. However, surely it does not necessitate this much, eh, "ventilation" in the house?



Condensation and the associated mould problems are a significant issue too, particularly as houses become more air tight.



Aodhán said:


> Would anybody have a safe solution to this currently unsatisfactory situation? Thanks.



A bit late now, but heat recovery ventilation could have been planned into the refurb. 

You can get [broken link removed] vents that will deal with the through draft issues, but these have a lower effective free area, so you may need more of them.


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