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How To Fit Trickle Vents Easily Using This Guide

How To Fit Trickle Vents Size Guide

You've come to this page because you need to know how to fit trickle vents to your window. If your window is made from upvc, wood or aluminium and you already have trickle vents fitted or at least the slots in the frame then this is 100 per cent the page to be on. If you are struggling with condensation, heat, mould or other moisture related problems and are looking to find a solution then trickle vents may or not be the solution. Scroll down to the troubleshooting and frequently asked questions section below for more on those points.

Let's start looking for a replacement trickle vent and we will do this by using the table below in conjunction with these three steps.

1. Take the old trickle vent off the window. This may be a clip-on fix or a screwfix. Screws are usually hidden underneath a cap which will need prising away.

2. Measure across the slot or slots that have been cut across the frame. You could have one, two or three slots depending on the size of the trickle vent used previously. If there are screw holes for self-tapping screws measure across the fixing centre points (the centre of the screws).

3. You will need to select a trickle vent from the table below studying the column 'Fixing Centres'. You may find the exact size for fixing centres which would end your search but if not consider a wider size for the fixing centres so that you can use something wider that bridges the slots and any current fixing holes in the frame at the moment. Then you can put two new slightly wider screw positions into the frame. Check the other dimensions to ensure the depth of the trickle vent covers the slot also and that a wider trickle vent will fit onto the window should you be increasing the length significantly. The new vent housing will then cover the slots in the frame and will be fixed to the frame securely.

How To Measure Trickle Vents

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Sizes Table For All Trickle Vents

ProductColourMaterial Made fromLength (mm) InternalHeight (mm)Depth Closed (mm)Fixing Centres (mm) InternalEA Rating (sqmm) 13/16mm SlotGEO Rating (sqmm) 13/16mm Slot
V2000WhitePlastic26518.5202421700/ ----2000/ ----
BrownPlastic26518.5202421700/ ----2000/ ----
GV 3000WhitePlastic30522232851800/25003000/4200
VAL 3300WhiteAluminium33520192932500/ ----3315/ ----
BrownAluminium33520192932500/ ----3315/ ----
TanAluminium33520192932500/ ----3315/ ----
BlackAluminium33520192932500/ ----3315/ ----
VXR 4000WhitePlastic3522116335----/ 4600----/ 4523
V4000WhitePlastic3662116335----/ 4600----/ 4507
BrownPlastic3662116335----/ 4600----/ 4507
GV 4000WhitePlastic40022233802700/32004000/5400
GV4000 CORDWhitePlastic40022233802700/32004000/5400
V4000 SLIMWhitePlastic41118.5203874400/ ----4106/ ----
BrownPlastic41118.5203874400/ ----4106/ ----
VAL 5100WhiteAluminium47520194334000/ ----5135/ ----
BrownAluminium47520194334000/ ----5135/ ----
TanAluminium47520194334000/ ----5135/ ----
BlackAluminium47520194334000/ ----5135/ ----
V5000WhitePlastic49518.5204735000/ ----5080/ ----
BrownPlastic49518.5204735000/ ----5080/ ----
GV 6000WhitePlastic55022235303400/42006000/8000
VAL 6300WhiteAluminium56520195235000/ ----6305/ ----
BrownAluminium56520195235000/ ----6305/ ----
TanAluminium56520195235000/ ----6305/ ----
BlackAluminium56520195235000/ ----6305/ ----
VAL 8000WhiteAluminium70020196586495/ ----8000/ ----
BrownAluminium70020196586495/ ----8000/ ----
TanAluminium70020196586495/ ----8000/ ----
BlackAluminium70020196586495/ ----8000/ ----


Column References

Product: This is the reference of the product and you can click this reference as it links to the product page to view more details.

Colour: Most trickle vents have several colours you can choose from and these are highlighted.

Material Made From: The construction of the vent is shown and is usually upvc (plastic) or an aluminium construction.

Length (mm) Internal: This is the overall size in millimetres of the internal vent and will give you some initial guidance to help with the replacement size. It is expressed as 'internal' as the external size may be slightly different. External trickle vent canopies are also available.

Height (mm): This is the size of the height of the vent (in millimetres) and is important when assessing how to fit trickle vents that the new trickle vent will cover over the height of the slot cut into your window.

Depth Closed (mm): This is the size the trickle vent projects away from the surface of the window when in the closed position.

Fixing Centres (mm) Internal: This is the size between the centre points of the two screw holes in the vent shown. You will need this to ensure that the screw positions will not be obstructed by the existing slots or existing screw holes on your frame.

EA Rating (sqmm) 13/16mm slot: Architects use this reference a lot to determine what is the Equivalent Area (EA) of the vent as this can calculate the overall room efficiency for air-flow that may be stipulated in Building regulations. In other words this is the amount of volume air that can pass through the external canopy, slots and the internal trickle vent. The design of the vent is important here as the more ribs, grilles or obstructions designed into the vent will reduce the amount of air that can flow through the construction. If you have a 13mm wide slot in your window the EA rating is shown for this as is the EA rating for a 16mm wide slot. If it is not shown then this vent will not be suitable for the size of slot indicated.

GEO Rating (sqmm) 13/16mm slot: This is an older interpretation of the vent size and capability and refers to the cross-sectional area of the slots cut into your window. This has been superseded by EA rating which is a more accurate assessment of the amount of air that travels through the complete assembly including the slot in the window.


My trickle vent doesn't sit flush onto the surface of the window.

Some vents have small lugs on the back that can drop into the slot for better alignment. If these are hindering the vent from being flush to the window surface then just slice them off with a Stanley type knife as they are very thin and easily removed.

My trickle vent is whistling in windy conditions

This happens rarely but in gusty conditions where the wind is head-on to the window it is possible. If the vent cannot be closed sufficiently you may need a baffle of some kind within the slot. These are specialist parts and may or may not be available.

I want a trickle vent that is draught-proof

Trickle vents are by design meant to be open and in some cases must be kept open for safety reasons, but of course there are times when the vent needs to be closed. If you are looking for a draught proof trickle vent that will be difficult to achieve particularly with moulded plastic vents. The aluminium trickle vents are much more rigid and have a foam pad to close onto so can be pretty close to being draught-proof.

My windows have a condensation problem, will trickle vents solve it?

It depends on the severity of the problem but it can help improve the situation. You need to establish the root cause of the condensation or get some professional advice as it may be more building related.

Will trickle vents make the bedroom cooler in summer?

It will help but it depends on how many vents you have in the room and whether that makes enough of a difference. It is difficult to say but it is best to assume the difference will be small.

I want to know how to fit trickle vents to windows that don't have them?

You can fit trickle vents in most cases but you would need a high degree of DIY skill as you need to drill or route slots into the frame. An important point to remember is that upvc windows may have steel or aluminium reinforcement inside the frame which can make the whole task a lot harder. There are many double glazing repair type companies around these days who can help you with work of this type.

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