Fixing blown sealed unit (not in situ!)

[RandomGrinch]

I've been meaning to attempt this for a while, but spurred on by @creamola's 'pioneering' attitude, here goes...

I have a small unit that's blown, it wouldn't be expensive to replace, but I thought it would be worth an experimental fix.
It's about 19 years old and has no coatings.


After taking it out, I pulled the tape off and immediately cut myself - wear gloves the corners are sharp!
I marked the inside and outside panes.
Then separated the spacer bars with a paint scraper - the lower seal was the damaged one and came apart surprisingly easily.
Not a good photo, but the lower spacer bar was a mess...


Once separated, the sealant was sliced away from the rear of the spacer bar.
The bar was pulled apart and the saturated desiccant was knocked out - 100 degrees for an hour and all dry...

In the meantime, all the old sealant was scraped off with a Stanley blade scraper and WD40, a spray of IPA afterwards cleaned up the WD40.
This was a long and very messy job.
The spacer bar was polished up, but it was pockmarked with aluminium corrosion - the new seal may not be perfect.

The desiccant was funneled back into the spacer and after some fastidious cleaning of the inside panes, the unit was reassembled using a whole tube of PU sealant...

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Again, a messy job!

The outside of the unit was then taped with Duct tape.

I've just done this so you don't have to!

Was it worth it?
Probably not, it was messy and took about 3 hours for a small unit, though material costs were less than £10 for the sealant and tape.
And as said earlier, this is an old unit, that wasn't coated - don't attempt this with coated panes.
Also, one of the interior panes was slightly etched by the condensation, but it is barely noticeable when installed.

Will it last?
Who knows, but I will keep you updated, if it fails again!

 

[catlad]

Well Done... but I've now got you down as crackpot

 

[ronniecabers]

Well done for attempting it ... needs to be pointed out that the sealant in an old unit like that will be different to modern sealants and they can be very tricky to get apart and the unit can easily be broken with too much force and you can easily slip with a stanley blade and cut yourself.
Did you reuse the dessicant? If so did you heat it in the oven gently to dry it out?
IF it lasts then an interesting result....I suspect within six months or one winter it will be fogging again

 

[RandomGrinch]

they can be very tricky to get apart and the unit can easily be broken with too much force and you can easily slip with a stanley blade and cut yourself.

Yes, the unit was treated tentatively - I used a scraper to "saw" away at the sealant, with the blade facing away from me at all times.
The failed bottom edge almost split away by itself, but the top and sides required more effort to separate.

Did you reuse the dessicant? If so did you heat it in the oven gently to dry it out?

Yes, it was gently dried out in the oven for an hour. The colour and consistency was decent afterwards, although not quite as much desiccant went back in, as came out!

IF it lasts then an interesting result....I suspect within six months or one winter it will be fogging again

As I said at the start, this is an experiment; I'm fully expecting it to fail. But this unit is on a sheltered side of the house, with only some direct morning sunlight.
It will be interesting to see how long it will last; I was surprised that this particular unit failed so badly to begin with.

 

[ronniecabers]

I fully understand the experiment side of it and well done for doing it. I was just adding some extra points in case anyone thought it was easy to split a unit down cleanly enough to reuse it .
The only thing I will add is that by the time you've ' dried ' the dessicant out ( which will certainly help it last ... perhaps up to 5 years would you believe), you won't have saved much , if anything on a smaller unit , larger units yes but they come with other problems.
And you were surprised it failed so badly? 19 years is very good for a sealed unit... industry expects 10-15. My guess would be it's south(ish ) facing too

 

[JohnD]

I had some sealed units replaced by a local specialist.

Luckily (?) my windows are sliding sash so I took them out and carried them down to the garden workbench to ease the job.

He visited once to take the measurements, and came back a week or two later and fitted the new units

If was far easier and quicker than I had foreseen, and the cost was not huge.

I now know that because fogged units are so common, there are lots of local independents in business. No need for new windows or a national company.

You just need to find a decent and well-established one.

 

[ronniecabers]

Absolutely John... the biggest boys ( Anglain/Everest and safestyle .... who incidentally are all trading names for Anglian Windows these days ) will always sell you new windows plenty of Independants out there ... we've replaced units in wood/pvc and ali for over 25 years along with other window/door repairs