ᐅ Central Vacuum Exhaust: Is an Open Pipe or a Sealed Wall Box More Appropriate?

Hello,

Our construction plan includes a central vacuum system (which is already planned in detail). However, there is one aspect I haven’t been able to resolve satisfactorily, and maybe someone here has good input? (By the way, this is not about the pros and cons of a central vacuum system. There are different opinions on that, but that’s another topic.)

Specifically, the exhaust duct uses a 100mm (4 inch) pipe that leads outside. Typically, there is just a bit of plastic on the outside with an insect screen underneath, and nothing more.

I wonder if it wouldn’t be much better to install a wall box that seals tightly and only allows air to pass when the vacuum is running. Otherwise, the pipe represents quite a large thermal bridge in an otherwise well-sealed house. There are various options available, and the exact model is not so important. Searching for “wall box blower door” online reveals several products designed to achieve this. They are usually intended for range hoods, but that does not make much difference in this case—range hoods also have a large hole in the wall when venting.

I’m not interested in ideas like “directing it into the ventilation system so the heat exchanger can handle it,” because the vacuum would push too much air in and disrupt the ventilation (and then I would be bringing that exhaust air back into the house, which is exactly what I want to avoid).

I can't help you with the central vacuum system itself, but isn't that technology outdated by now? About 10-12 years ago, people still mentioned it quite often here in the forum, but with cordless vacuum cleaners and the continuously improving vacuum-and-mop robots, it seems like a feature in the house that’s no longer necessary nowadays. Are you really sure it’s worth investing money in it?

Musketier schrieb:

About 10 to 12 years ago, you would still see this discussed quite often in the forum. But with cordless vacuum cleaners and the constantly improving vacuum-and-mop robots, this has become an outdated feature in the house that is no longer really needed today. Are you really sure it’s worth investing money in it?

Regarding:

Ganneff schrieb:

(Oh, this isn’t about the pros and cons of a central vacuum system. There are different opinions on that, but that’s another topic.)

Yes, we’re sure. That’s why I said it’s a different topic.

It is really just a relic from the past, like a fireplace.
I would generally advise against it.

If you still want to go ahead with it, you should seek thorough professional advice.

Ganneff schrieb:

Oh, it’s not about the pros and cons of a central vacuum system. There are different opinions on that, but that’s a different topic.

Even if you didn’t want to make it the topic, the pros and cons were still discussed ten years ago. The fact that central vacuum systems hardly play any role in this forum anymore actually suggests that for most homeowners, there are probably very few “pros” left. Since most users have built or are currently building in recent years, I personally doubt you will find meaningful advice or experience here.

You still seem to see enough pros for yourselves, so of course I hope that someone can still provide a useful answer to your question.

RotorMotor schrieb:

It’s just a relic from the past, like a fireplace.

PS: At least a fireplace remains an emergency option in case the heating fails or there is a prolonged power outage, and fire always adds a cozy atmosphere—even if from an energy perspective it no longer fits modern houses. But running around the house with a long hose feels more like hotel cleaning to me.

Off topic at first: Central vacuum systems are outdated nowadays due to very good cordless vacuum cleaners being available, because a) they are much too expensive for the performance, and b) they are still too inconvenient to use.

Regarding the question: Of course, a simple opening in a new build is practically a disaster. That’s not acceptable. You first build a tight house and then install an opening through which a lot of cold outside air can flow in. A wall box is a must.
If you use a wall box, then an electronically controlled one. Although the central vacuum system operates at a high negative pressure, it ultimately has a rather low volume flow. More in the range where a mechanical flap just barely opens (not comparable to the volume of an exhaust hood). So choose an electronically controlled one that opens when the vacuum is turned on. This also has the advantage that particles that might settle and block the opening won’t hinder it as much as they possibly would with a mechanical one.