A sealed unit that has misted inside the glass

2 days ago
3 min read

Introduction

A customer rings to say one of the windows fitted eighteen months ago has gone cloudy between the panes. Sometimes there are visible water droplets, sometimes a haze that appears in certain light, and sometimes a tide mark along the bottom edge.

Unlike most complaints, this one is not really a diagnostic puzzle. Misting between the panes means the sealed unit has failed and moisture has entered the cavity. It is not condensation on the surface, it cannot be cleaned, and it will not improve. The only questions are why it failed and how quickly you replace it. Answer the second one first.

1. A sealed unit that has misted inside has failed and needs replacing

There is no repair, so do not let the conversation drift. Be decisive from the outset.

Explain what has happened clearly

The perimeter seal has let go, the desiccant is saturated, and moisture is now inside a sealed cavity. Plain language, no hedging. Show them the tide mark.

Say immediately that the unit will be replaced

If it is within warranty, the answer is yes and it should be the first thing you say. Making a customer push for an obvious outcome is what creates bad reviews. Say yes on the call.

2. Establish the likely cause, quietly

You need to know even though the customer does not. The cause affects the rest of the job.

Drainage and installation

Blocked or missing drainage slots, a unit sitting in water, incorrect packing or setting blocks. These are installation issues and they will recur if not corrected. Check them on site.

Unit manufacture or handling

A poor seal from the supplier, or damage in transit or fitting. This is a supplier conversation, not a customer one. Keep it in the background.

3. Handle the warranty properly

The paperwork is where firms lose money and goodwill. Know it before you ring.

Know the terms and the dates

What the unit is guaranteed for, what your installation is guaranteed for, and whether the two differ. Have this to hand before you ring the customer back.

Do not make the customer chase the supplier

Handle the claim yourself. A customer who is told to contact a manufacturer has been abandoned in their own view, whatever the contract says.

4. Fix the cause as well as the symptom

Otherwise the replacement fails too. Treat the cause properly.

Clear or create the drainage

Check the slots, the gaskets, and whether the frame is draining outward. A replacement unit in a wet rebate will fail again in a few years.

Check the other windows while you are there

If one has failed through installation, the rest of the job may be at risk. Looking now is far cheaper than returning four times.

5. Communicate the timeline honestly

Waiting is the part that annoys people. Not the failure itself.

Give a realistic lead time and stick to it

Units are made to order and toughened glass takes time. Say four weeks and mean it rather than saying two and missing it.

Keep them updated without being chased

One message when the unit is ordered and one when it is due. That is the difference between a warranty claim and a complaint.

Conclusion

Misting between the panes means the sealed unit has failed. There is nothing to diagnose and nothing to clean, so say plainly what has happened and, if it is in warranty, confirm the replacement as the first thing you say rather than making the customer push for it.

Establish the cause for your own purposes — blocked drainage, a unit sitting in water, incorrect packing, or a supplier seal failure — and handle the supplier claim yourself rather than sending the customer to a manufacturer. Fix the drainage so the replacement does not fail too, check the other windows while you are there, then give an honest lead time and update them without being chased.