What Are Trickle Vents?
Handles & Hinges UPVC Maintenance Ltd is a UK specialist in UPVC door and window parts. A trickle vent is a small controllable opening in a window or door frame that lets a steady flow of fresh air into a room without fully opening the window.
How a trickle vent works
- A narrow slot is routed in the sash or frame.
- An external canopy keeps rain out; an internal vent controls the airflow (open/close or filtered).
- Air passes continuously in small amounts (“trickle”), improving background ventilation.
Common types
| Type | Where used | Notes |
|---|---|---|
| Over-frame slot vent | Retrofits to most UPVC windows | Internal controller + external canopy; screws through the frame |
| Glazed-in vent | New frames or when replacing glass | Built into the glazing bead/spacer; neat appearance |
| Acoustic vent | Noisy locations | Designed to reduce sound transmission while ventilating |
| Filtered vent | Dusty/urban areas | Includes mesh/filters; keeps insects and debris out |
How to choose a trickle vent (quick steps)
- Measure the window section — note frame thickness and where the vent will sit (top of sash/frame).
- Pick a vent length & capacity — choose a model whose stated airflow/“equivalent area” suits the room size and regulatory guidance.
- Decide features — standard vs. acoustic, filtered, or night-latch style control.
- Choose colour/finish — white, brown, black, anthracite, etc., to match your frames.
Basic retrofit overview
Note: Drilling or routing frames may affect warranties; proceed only if you’re confident, or ask a professional.
- Mark the slot position at the head of the sash/frame (check clearance to steel reinforcement).
- Rout/drill the slot to the vent maker’s template; deburr and clean swarf.
- Fix the external canopy and internal control unit with the provided screws.
- Test open/close and confirm smooth airflow (you should feel a faint draft when open).
FAQ
Do trickle vents make rooms colder? They allow a small, controlled airflow. In practice they reduce moisture and improve air quality with minimal heat loss compared with opening a window.
Where should they be fitted? Typically at the head (top) of the window for best airflow and to avoid rain ingress.
Are they required? Many new or refurbished properties need background ventilation. Check current local building regulations or speak to your installer/landlord.
Can I add them to existing windows? Often yes with over-frame vents. If unsure about reinforcement or glazing lines, seek advice before cutting.