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I recently had my windows replaced with Alside vinyl and they are suppose to be Low E & Argon filled. How do I know if they are argon filled? Of course the labels state they are, however, I don't see a plug that would have been used to seal in the gas. I only see a screw at the top of all the windows. Also, when fogging is mentioned, does it mean, the morning dew on the outside of the windows?

 

Here's where "trust" comes into play. Don't go messing with the IG just so you can satisfy your need to know. Manufacturers seal up the gas entry point prior to framing it. If they say it is argon gas, then that is what it is. Reputations are built on quality, and no one wants to lose a good reputation. Fogging is when there is damage to the IG (like someone poking around to find out if there is argon gas inside), and the gas escapes, and is replaced by moist air. This moist air has no where to go, so with the heating and cooling it changes from a gas to a solid and fogs the window between the panes. The normal condensation on the outside is not fogging.

 

If you examine the spacer bar between the 2 panes of glass, it is sometimes apparent that argon has been filled. Other times it is not so obvious. Sometimes the technique used to fill IGU's involves two holes. One for the gas to enter, another for the ambient air inside the IGU to escape as the unit is being filled. Sometimes you will see these 2 holes, sometimes you won't.

At any rate, I agree with what Chandler mentioned. If it's on the NFRC sticker, you can guarantee that you have the correct glass and gas fill.

 

Thanks! The only problem with the labels is, when the company replaced the window sashs, there was no NFRC label.

 

You might be able to find an NFRC sticker somewhere on the masterframe of the window. Above the top sash, or along the side somewhere. Usually there is one hidden somewhere, in addition to the one on the glass. It probably only tells about the window, however... not the glass.

 

Another way to discern if you have the argon gas is to measure the glass temperature. You can buy a digital infrared thermometer (I've bought a few from RadioShack for about $40 each), which will measure the surface temperature of whatever the invisible beam strikes. Incidently, my ice cubes are 4°, a 60 watt lightbulb is 212°, etc. Anyway, if it's 0° outside and around 70° inside the home, a double glazed window should be approximately 44° if it's clear double glass, about 51° if it's Low E coated, and about 57° if it's Low E coated with argon gas. Those measurements would only apply to the center of the glass because the edge of the glass is colder due to the metal spacer (usually) that separates the panes. You would have to take the measurements on a window that is not covered by any window treatments (blinds, shades, etc. drop the glass temperature by 21° when they cover the glass), that is not blocked by any furniture (desks, lamps, couches drop the glass temperature because they block the air flow in the home that would normally circulate against the glass), and you would have to take the temperature preferrably at night so that the sun is not warming up the glass.

Again, all of those statistics are based on a very cold temperature of 0° outside. If it doesn't ever get that cold in your climate (congratulations), there are different stats that you would be looking for that I haven't presented above.