I live in a house which consists of a 17 year old extension on a 40 something year old cottage. The two main bedrooms are the only rooms in the house with air vents. They are also two of the coldest rooms in the house.

The vents are basically just holes in the wall covered by plastic vent covers. They have a switch to slide them 'closed' (I leave them closed permanently). Even on closed I can feel a cold breeze if I hold my hand to them. I can also hear the wind whistling through them at night.

As it comes into winter I feel like all the heat in these rooms is escaping through these vents. I keep thinking I should just stuff some insulation in there, even just for the winter months.

Is blocking them a bad idea? Long term, can I replace these with a more insulated kind that won't lose as much heat?

  • 1
    What kind of heating system do you have? Forced air? Radiant? Wood stove? Are these return vents or just random wall vents?
    – Freiheit
    Nov 21, 2013 at 17:19
  • I have an oil fired boiler at the other end of the house which pumps water around ordinary rads. They're just random wall vents. My wife believes that they need to be open to allow air flow through the house, but I believe we're just losing heat
    – roryok
    Nov 21, 2013 at 19:45

1 Answer 1


Go ahead and block them off.

My house was built in the same era and has similar vents in the bedrooms. I believe the rationale is the construction of this era had become so tight that infiltration alone was insufficient to provide fresh air into the house, so these vents were installed as intentional infiltration.

In my case, I'm not convinced the construction was all that tight. Even if yours is that tight, you get enough infiltration from the old section that I don't think you will have an issue with stale air if the vents were sealed off with insulation. Even if you do notice the air being stale afterwards, it's easy enough to remove the insulation to regain some infiltration.

If you do find the need for some fresh air, the only energy efficient solution is an air to air heat exchanger that heats incoming air with the residual heat of outgoing air. These units are installed in homes that are truly tightly built. As in refrigerator like tightness. Without these exchangers air in such houses becomes noticeably stale.

  • thanks. if stale air is the only thing I have to worry about, I can live with that for the winter!
    – roryok
    Nov 22, 2013 at 7:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.