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Blocking up wall vents

gnolan

I currently have our wall vents upstairs blocked up. I've done this for the reasons most people do it; the house is freezing with them because they're just a big hole in the wall. I know there's some people who will staunchly argue that they shouldn't be blocked, which is fair enough, but I've got humidity monitors in each room, we regularly open the windows fully, and we've got a dehumidifier.

I have a temporary solution in place that involves a load of insulation stuffed into them. We're having the house replastered in a few weeks though and I'd like a more permanent solution. Can anyone suggest anything that won't involve me on a ladder, and that I could hopefully do handily myself before the plasterer comes?

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10-10-20

A pipe bung?

https://duckduckgo.com/?t=lm&q=pipe+bung&ia=web

Nigzcurran

Could you block them partially and allow a small bit of ventilation?

cobham

I think you must leave vents there and do not permanantly close. The next occupant of your house might not be so diligent in opening windows/using dehumidifiers. Also if passive ventilation is needed if house is unoccupied for any length of time.

dbas

Something like this. Acoustically lined and humidity activated. You definitely need fresh air in those rooms, but they cause draughts of not installed properly

https://buildstore.ie/fresh-99h-wall-vent.html

Idioteque

Have you monitored the humidity during the winter yet? That's when most humidity issues arise due to poor ventilation leading to mould. If your diligent opening windows in the winter in all rooms fair play but I think the heat loss (and cost) from a wall vent would be a lot less than opening all the windows in habitable rooms in the depths of winter.

I use one of these on the internal wall which allows me to control the amount of air on particularly windy days. I also use a cowl on the external wall at the back of the house to reduce straight-through gusts as the back gets the worst of wind.

There's also loads of automated options with humidity sensors etc. or sound reduction if noise is an issue also.

I know its not what you were asking before but worth considering the likes of the above. If you're adamant to block off the wall vents you could spray expanding foam in the pipe and then patch hole with plasterboard.

mulbot

Just buy slide vents, close over whichever side the wind is blowing into, very simple.

gnolan

@cobham I think you must leave vents there and do not permanantly close. The next occupant of your house might not be so diligent in opening windows/using dehumidifiers. Also if passive ventilation is needed if house is unoccupied for any length of time

I don't see the same vents on other houses in the area. The houses were built in 1930 and ours is the only one with them. I don't think other houses have had them filled as the houses are a distinctive brick and you'd notice on at least one or two if they'd been patched. The house was rented before we bought it and I'm assuming that a rental inspector advised the installation of the vents.

@dbas Something like this. Acoustically lined and humidity activated. You definitely need fresh air in those rooms, but they cause draughts of not installed properly

What I don't understand about the humidity activated fans are that it's often > 75% relative humidity in Ireland; it can be just as humid, if not more humid outside the house. Would these not just be constantly pumping cold air into the house through the winter?

Have you monitored the humidity during the winter yet? That's when most humidity issues arise due to poor ventilation leading to mould. If your diligent opening windows in the winter in all rooms fair play but I think the heat loss (and cost) from a wall vent would be a lot less than opening all the windows in habitable rooms in the depths of winter.

I have. We wouldn't open the windows as I've described every day but probably for a total of 30 - 60 mins a week in combination with the dehumidifier

@mulbot Just buy slide vents, close over whichever side the wind is blowing into, very simple.

Do you mean like map vents/hit and miss vents? These are what we have. Even when closed the vents are the same temperature as outside, meaning in winter the rooms have a four-inch fridge. I've checked this with a thermal camera.

Lumen

https://www.boards.ie/discussion/comment/122571493#Comment_122571493

What I don't understand about the humidity activated fans are that it's often > 75% relative humidity in Ireland; it can be just as humid, if not more humid outside the house. Would these not just be constantly pumping cold air into the house through the winter?

RH drops when the air is heated.

Slightly Kwackers

https://www.boards.ie/discussion/2058367052/blocking-up-wall-vents

I used cement as a permanent job downstairs.

The vent was a joke as even with new doors and windows the airchanges are frequent.

Were I not able to cement it, I would go for foam. line what you don't want it to stick to with a plastic bag for ease of removal when the asphyxiated corpses start to pong a bit :-)

Tefral

These are pretty good https://munsterhrv.ie/shop/ols/products/wall-vent

User567363

This thread is confusing, its summertime, are you talking about issues in winter or are you cold even now, we have our vents and even most windows wide open last few months

geographica

https://www.boards.ie/discussion/comment/122571701#Comment_122571701

No better time to do it than now

Allinall

if the house is freezing you’ve got bigger issues.

Open vents won’t make much of a difference.

Concentrate on that first.

greasepalm

If you have gas heating you will need ventilation , sitting room had a gas fire for looks and not for heat. Gas provider cut a hole in the floor boards to add a vent .

Now removed as fire does not be used or work and slid some sheeting i had under the carpet and hole is blanked off.

A few years ago added a fan in the outer wall to extract fumes in the downstairs toilet and at times cold air would blow in creating a draught. Bought some 4 or 5" pipe to connect to back of fan through the metal vent where i cut to slide pipe in. On the exterior wall i have 3 blades which open to vent and suppose to shut when fan stops , and sometimes stuck open. Good old silicone put on the bottom of the blades for more weight and has kept them closed most of the time

Explosive_Cornflake

spray foam and a bit of bonding over it.

I had the same concern about blocking them up, but I have trickle vents on the windows which are very rarely closed. I've not had any issues in a good few years now.

User567363

You dont need to block them all just the ones facing the windy west of ireland, if you live in the country plant 100 leylandies to your west and in 15years your gonna have a paradise

If I am still on here, get in touch and i will join ya for a beer

gnolan

https://www.boards.ie/discussion/comment/122571557#Comment_122571557

I understand that, but if I'm in a room at 20C and 65rh and the vent kicks in and blows air in at 12C and 80rh, how does not increase the humidity and lower the temperature in the room?

gnolan

https://www.boards.ie/discussion/comment/122571701#Comment_122571701

Yes, with the summer ending and colder temps on the way I'm looking for a more permanent solution. We, too, have had the windows open over the summer

mulbot

https://www.boards.ie/discussion/comment/122571493#Comment_122571493

Yes those type. The cold temperature at the vent face isn't really affecting the room , I'm talking about closing off the flow of cold air coming into the room/s. I've had that problem, front of house faces S/W, I just slide over the vents, stops the cold air, I open them periodically.

gnolan

https://www.boards.ie/discussion/comment/122571721#Comment_122571721

I am, we've had triple glazing installed and we're having the attic insulated as well as the suspended timber floor downstairs.

gnolan

https://www.boards.ie/discussion/comment/122571773#Comment_122571773

Do you think I could some plastic behind the exterior grille? My concern is that the foam will expand out the exterior vent and look a mess and I don't want to get up on a ladder to sort it.

Hobby farmer

If you're intent on blocking them then yes put something in against the outer vent cover and foam. Go slow with it, spray some/ let it expand spray more so on so on. Try leave it shy of the surface so either you or the plasterer can ad some bonding before skimming it.

Bogwoppit

I retrofitted mhrv a few years ago and blocked my vents.
I put a bin liner inside the hole and filled the bin liner with expanding foam. The bin liner should make it easy to open the vents at a later date if needed.

Brickie777

Shouldn't block up the vents , especially if there is gas being used in the house , in the last so called boom the builders specified wall vents in most dwellings , unfortunately occasionally when plasterboard was put up they forgot to cut out the vents , leading to fatalities from gas in some cases , in a lot of newer houses there are vents in the windows and in this case no wall vents required

Lumen

https://www.boards.ie/discussion/comment/122571890#Comment_122571890

In your example, if you completely replace that indoor air with outdoor air and heat it to 20C, the RH will be 49%.

You only have to warm it up to 16C to bring the RH down to 62%.

dbas

https://www.boards.ie/discussion/comment/122571890#Comment_122571890

i0522-74-psychometric-chart-aw-web-ready-1.pdf

It's too tricky to explain on here but the attached is a psychometric chart. Pick a temperature from horizontal axis, draw straight line up from that temp to meet the curved humidity line. Mark that point, and draw horizontal line from that point to the right side. That shows moisture content of the air at that temp/humidity. Winter outside air is relatively dry

[Deleted User]

https://www.boards.ie/discussion/comment/122571721#Comment_122571721

Ah they do though. A 4 inch hole in the wall with a flow of cold air will make a huge difference to the room temp in minutes.

I wouldnt be blocking though. Id be looking at a heat recover vent. Not sure how effective they are though.

condra

I just bought a gaff and the previous occupant had the vents filled with nappies. Unused, of course, but still, I'm not sure if it's gross or clever.

pinkfloyd34

If you have a fireplace that is not in use then you can block up the chimney with a pillow. This stopped some of the draughts. I had to remove the pillow though when the power went recently and light a fire. With the air vent it felt like the heat was just being sucked out of the room and up the chimney.

I did hear of people filling the vents with newspaper just to weaken the airflow but not completely stop it. I still have to do this with mine.

10-10-20

https://www.boards.ie/discussion/comment/123150689#Comment_123150689

A few rolled-up socks placed loosely inside will restrict the air-flow too, but retain just enough for some flow.