I performed a search here and only found a little bit.

I'm strongly considering Alpen 525 series windows for my home in Trinidad.

Alpen's are made in Colorado near Denver, so their elevation is appx 5300'

I assume they install breather tubes to allow the windows to acclimate during shipment and once the arrive at their final destination?

It doesn't appear there is a choice in the matter and I assume Breather tubes are a pretty good idea so the windows don't break from pressure changes when being transported.

Should I be concerned?  My home in Trinidad is 150' above sea level.  And I assume the tubes need to be sealed off once the windows have stabilized to the sea level elevation, and before installation?
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I have 21 windows of various sizes in the home (which includes 4 sliding glass door windows) and the estimate came back to a little over $30k (includes tax and shipping to the job site).

I also received bids on MilGard vinyl (about $11k) and Milgard Fiberglass (about $23k).  I have not asked for a Marvin Integrity bid, but I doubt it will be much cheaper than the Alpen, and from everything I've read about Alpen, they are a superior window than Marvin Integrity.  The specs support this too.

the tubes can be crimped, cut and pushed under the gaskets after installation according to my dealer.

So why do window mfgs bother to fill the gaps with inert gas (like argon) if the tubes allow it leak out. I mean, I understand why the tubes are installed, but don't understand the inert gas effort, if it is gone by the time it is installed.

Double check but some manufacturers attach balloons to the tubes in order to retain the gas. Plus the tubes are usually on the top of the IGU's as argon is heavier than air.

Posted By JohnRLee on 05 Jun 2013 09:22 PM
So why do window mfgs bother to fill the gaps with inert gas (like argon) if the tubes allow it leak out. I mean, I understand why the tubes are installed, but don't understand the inert gas effort, if it is gone by the time it is installed.

Because they can charge you more $$$ for the argon gas, that's why. If they are custom made for your project, you can request for them to NOT put in the gas. If they are mass produced standard sized windows, the gas is installed at the factory on all the windows.

Unless they assemble the windows at the same elevation and transport them without changing elevations, tubes are required because it can create positive or negative pressures depending on the elevation and damage the glazing.

They do offer one way pressure valves but I don't know how effective they are.

Eventually ALL windows will leak out the argon or other gases over time. It might take 5-10-15 years or more but eventually the seals are never 100% and gases leak out. I like windows with replaceable exterior and interior glazing seals because they allow for future replacement. When they use silicone, that becomes a nightmare to remove, clean and replace, if it becomes necessary.

Posted By JohnRLee on 04 Jun 2013 11:05 AM


I also received bids on MilGard vinyl (about $11k) and Milgard Fiberglass (about $23k).  I have not asked for a Marvin Integrity bid, but I doubt it will be much cheaper than the Alpen, and from everything I've read about Alpen, they are a superior window than Marvin Integrity.  The specs support this too.

I agree, the Alpen are a better window than the Marvin or Milgard.