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Thermos replacement in Montreal
Is your thermos pane fogged between the two panes? We replace the window thermos (the sealed unit) in your existing frame — at a fraction of the price of a new window.
Understanding
The sealed unit: your barrier against the Montreal cold
A modern window is not just a pane. It's a sealed unit, also called a "thermos": two or three panes separated by a space filled with an insulating gas (usually argon), all sealed airtight.
This glass sandwich plays a crucial role in Montreal's climate: it slows heat transfer, limits condensation and improves your comfort, summer and winter. When it works well, you don't even think about it.
When its seal fails, that's when the fog appears — and that's when we step in, replacing only this unit, without touching the frame or the rest of the window.
Why replace only the glass
Your frame is still solid. Replacing only the sealed unit within the existing frame costs 3 to 5 times less than a full window, takes 1 to 2 hours per pane, and preserves the character of your building.
Warning signs
How do you know the thermos needs replacing?
Fog between the panes
Condensation or droplets trapped between the two panes, impossible to wipe.
Whitish film
A permanent milky haze that dulls the view outside.
Mineral deposit
Whitish stains or a crystallized haze left by evaporated moisture.
Colder pane
The inner surface becomes abnormally cold in winter, a sign of lost insulation.
Draft
A draft sensation near the window, even when closed.
Rising bills
An increase in heating costs linked to lost insulation.
The causes
Why does the seal fail?
A sealed unit's seal is not eternal. Several factors eventually cause it to fail:
- The age of the sealed unit (often between 10 and 25 years)
- Montreal's repeated freeze-and-thaw cycles
- Prolonged sun exposure that wears out the seal
- An original manufacturing defect
- A frame that works or shifts with the building
Did you know?
A sealed unit that has lost its seal loses much of its insulating power. It's not just an aesthetic issue: it's literally heat escaping. Replacing the thermos restores the original insulation.
Our process
A clean replacement, from diagnosis to warranty
Diagnosis
We confirm the frame is sound and only the thermos needs replacing.
Sound frame confirmed
We check the frame's condition: if it's good, we keep it entirely.
Precise measurement
We take the exact dimensions of the sealed unit, to the millimetre.
New custom thermos
We make a new double, triple, Low-E or argon-filled unit to your needs.
Removal and installation
We remove the old unit and install the new one in your existing frame.
Sealing, cleaning, warranty
We seal cleanly, clean up and provide a written warranty against seal failure.
Glass options
Choose the right sealed unit
Double glazing
Two panes + argon gas. The reliable standard for most windows.
Triple glazing
Three panes for superior insulation, ideal on north-facing facades.
Low-E + argon
A low-emissivity coating that reflects heat and improves energy efficiency.
Pricing and timelines
From
$150 / unit
Per square foot
$22 – $38
Triple glazing
+ 20 – 40%
Custom fabrication in 24 to 72 hours. Written warranty against seal failure included.
See the full pricing gridGo further
More questions on your mind?
FAQ
Frequently asked questions
How much does a thermos replacement cost in Montreal?
Our prices start at around $150 per unit. The exact cost depends on the size, glass type (double, triple, Low-E) and quantity. See our Pricing page for a detailed breakdown, or request a free quote: the price is confirmed at the free diagnosis.
How long does the replacement take?
Diagnosis and measurement are done quickly on site. Your sealed unit is then custom-made within 24 to 72 hours and installed cleanly. In most cases, everything is settled in under a week.
Do I need to replace the whole window?
No, in most cases. If your frame is sound, only the thermos (sealed unit) is replaced. It's far more economical and just as durable. If the frame is damaged, we tell you honestly and refer you to our RBQ partner installers.
Is your replacement guaranteed?
Yes. Every sealed-unit replacement is covered by a written warranty against seal failure. You leave with a durable solution, not a temporary fix.
Is defogging a valid alternative?
No. Defogging (injection) masks the fog temporarily but restores neither the seal nor the insulation. Only replacing the sealed unit fixes the problem for good.
Ready for clear windows again?
Free quote, honest diagnosis and transparent pricing. Call us or request your quote now.
Request your free quote
Fast response, no obligation. The diagnosis is always free.