Old 60's fresh air ventilation system

[Terminatrix]

Hello everyone!

I own a house built around 1960 and it has these ventilation boxes on the wall. A larger one in the living room, which is wired into the mains (see 1st pic below). And then 3 smaller units in the bedrooms that are mounted higher up and don't have any wires or switches (see 2nd pic).

I assume that back in the day, they were just an alternative to opening a window and allowing fresh air in?

Could I simply remove them and place a ventilation grill over them? Does anyone know why the smaller bedroom units have no visible wires or switches? How would they work?

Thanks in advance!

 

[JohnD]

Is there an airbrick on the other side of the wall?

How did you know they are ventilation units?

I wonder if they contain dust or pollen filters.

"Airprime" is today a name used for wireless equipment.

 

[JohnD]

Well fancy that

Company closed down in 1982.

Name of Company: AIRPRIME EQUIPMENT LIMITED.
Nature of Business: VENTILATIONS EQUIPMENT
MANUFACTURERS.
Address of Registered Office: 4 Charterhouse Square,
London EC1M 6EN.
Liquidators' Names and Address: M. R. Dorrington, A
W. Wainwright, 4 Charterhouse Square, London EC1M
6EN.
Date of Appointment: 20th April 1982.
By whom Appointed: Members and Creditors. (055)

 

[Terminatrix]

So when I switch on the Living room unit, I can feel that it blows out air in the opening at the bottom. It has 2 vents on the outside. The bedroom units have 1 exterior vent.

I guess I could just unscrew the unit cover to see what's inside, but I'm sure that I've seen these in other people's homes, so I thought that I would ask here first.

Thanks