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How to fit an air conditioner window seal

Updated: 20 October 2026

The paper says side A while the drawing says side B. That clash shows up in the shared MOEGFY reviews. This is how to fit an air conditioner window seal on a hinged window: clean the frame, keep the tape off the glass, put the wide cloth on the sash that moves, and do not shut that sash on the fabric. Prices and the product table stay on our [air conditioner window seal comparison](/hub/cooling/air-conditioner-window-seal). Peter F. used Sealey's SACWK1 sheet, Electrovision's EH1927 sheet, and the amazon.co.uk review notes from 19 October 2026. It is not a timed install. A qualifying purchase can earn a commission at no extra cost to you.

The paper says side A while the drawing says side B. That clash shows up in the shared MOEGFY reviews.

Our top picks

Derwit Derwit 4 m casement window seal

Best overall

Derwit Derwit 4 m casement window seal
6.7/10about £17.99
View offer
DREO DREO 400 cm window seal

Rank 2

DREO DREO 400 cm window seal
7.3/10about £19.99
View offer
Machine-YA Machine-YA 300 cm window seal

Best value

Machine-YA Machine-YA 300 cm window seal
7.2/10about £16.38
View offer
On this page
  1. 1.Before any tape
  2. 2.Frame, then the opening sash
  3. 3.Zip, spare fabric, and the first hour
  4. 4.Heat, wind, and an open window

Before any tape

Measure before you peel anything. On a hinged window that is the top rail and the two uprights, skipping the hinge. A Machine-YA reviewer says the diagram draws four sides and the seal does not. A 90 cm top and two 110 cm uprights is 310 cm, which misses the 300 cm cloths. If you are still choosing a length, use the buying guide first. Clean the frame and let it dry. Paint and grease are why tape lets go the same afternoon. LYUNIT reviewers describe glue perishing around 30°C. Derwit reviewers had to work around security bolts. A sash is the wrong opening. Confirm the hinge on the casement page before you commit the adhesive.

Frame, then the opening sash

Sealey's instructions say not to adhere the tape to the glass. Put the narrow tape on the frame, working from the centre outward, and put the wide cloth on the sash that sits ajar. If the leaflet swaps A and B against the picture, follow the sash that moves. MOEGFY's shared reviews describe that clash. Press the tape and give it a minute before the cloth takes the hose. Leave the hinge uncovered, or the sash will chew the fabric. You should still see the lock. If the tape is short of a bottom-hung sash, which one Derwit reviewer reported, do not stretch it until the ends fail.
Derwit Derwit 4 m casement window seal

Testsieger

Derwit Derwit 4 m casement window seal
6.7/10about £17.99
View offer

Zip, spare fabric, and the first hour

Open the zip and pass the hose through before you shut the sash further. Electrovision asks for the hose to project at least 5 inches, about 13 cm, past the cloth, with the zip pulls cable-tied. MOEGFY, Machine-YA, and EGNBU reviewers say the zipper still leaves a gap. MOEGFY's listing says a minimal gap may remain. Roll spare cloth rather than stuffing it into the closing gap. A 400 cm strip on a small casement is baggy in the MOEGFY reviews. Sealey tells you to detach the cloth to close the window fully. If the sash bites the cloth, you have gone too far. After an hour, check the join where the two ends meet.

Heat, wind, and an open window

Recheck the tape after the first hot afternoon. EGNBU reviews include thick glue after about a month. Machine-YA tape let go after a few damp nights. VOLIKRA reviews run from a few days to about six weeks. Warm soapy water is kinder to uPVC than a blade. Stop the unit if the cloth hangs by one corner. Electrovision says not to use the seal in strong wind, and that the window is not secure while the kit is fitted. Take the cloth down to lock the window when you leave. An open sash is a fall risk for children and pets. Get a joiner if the sash will not stay ajar safely, the hinge is damaged, or you are about to drill the frame. None of these listings asks you to drill. For a longer spell, see fabric versus a rigid panel.

Common questions

Do you stick the tape to the glass?
No. Sealey's sheet says not to adhere the tape to the glass. Put it on the frame and on the sash edge that forms the gap. Glass is a poor long-term surface for this job, and a smear of adhesive on the pane is the residue reviewers complain about when the kit comes down.
Which side of the cloth goes on the opening sash?
The wide side goes on the sash that moves, and the narrow tape goes on the fixed frame, working from the centre out. If the printed A and B labels disagree with the drawing, follow that rule rather than the caption. MOEGFY reviews describe instructions and a video that contradict each other on this point.
Can you still close the window?
You can close it if you unhook the cloth first, which is what Sealey tells you to do so the fabric is not jammed. Leaving the cloth in place and forcing the sash is how the material tears. One review says a window closed with the seal still on. Do not treat that as safe for every hinge.
How far should the hose stick through?
Electrovision's casement instructions say at least 5 inches, about 13 cm, past the cloth, with the zip pulls cable-tied. Feel for a gap with the unit on. These kits still leak a little at the zipper. Pulling the hose so hard that it drags the tape off the frame is too far.
What if the instructions contradict the picture?
Follow the window. The moving sash gets the wide cloth, the frame gets the tape, and the hinge stays clear. A contradictory caption is common enough in this set that it should not decide which way round the kit goes. If both the sheet and the window are unclear, stop before the adhesive is committed.
When should you take it down for security?
Take it down when you leave and need the window shut and locked, and take it down in strong wind. Electrovision states that the window is not secure with the seal in use. An open sash is also a fall risk for children and pets. The cloth is a ventilation gap with a hose in it, not a lock.

Related pages

Best window seal

Air conditioner window seal

Choosing a portable air conditioner window seal kit

Casement window seal for a portable air conditioner

Fabric window seal vs acrylic panel for portable AC

Sources

Public UK sources from the research digest, used for this page on 20 October 2026. Prices, stars, and review counts are the amazon.co.uk figures in the 19 October 2026 snapshot. NHS and GOV.UK pages do not recommend these kits.

  1. NHS: heatwave, how to cope in hot weather (retrieved 19 October 2026)
  2. GOV.UK: beat the heat, keep cool at home (retrieved 19 October 2026)
  3. Consumer Rights Act 2015, section 9 (retrieved 19 October 2026)
  4. GOV.UK: product safety advice for businesses (retrieved 19 October 2026)
  5. GOV.UK: reporting product safety issues (retrieved 19 October 2026)
  6. Aircon Revolution: window seal kits for portable air conditioners (retrieved 19 October 2026)
  7. Ideal Home: portable air conditioner window kits (retrieved 19 October 2026)
  8. Appliances Direct: how to install home air conditioning (retrieved 19 October 2026)