ice on inside of NEW sliding doors

I recently (summer) installed a new sliding glass door from Anderson. I liked the look of the door and it had low e-glass, etc. But, now that we've hit winter in Buffalo, I am noticing something strange occuring with the door. Last night, there was a big chuck of ice on the inside bottom of the door near where it seals to the jam on the sliding door. This suprised me as I thought by spending the $800 for the higher quality door, I shouldn't expect to be pulling off chunks of ice from the bottom of the door. At the bottom of the door, there is an aluminum sill that gets really cold. This sill is freezing compared to any other part of the door when temps drop.
My thoughts are that because the aluminum is a good conductor of heat or cold in this case, the low temps that we have been having (1°F) are being brought into the house via this aluminum that goes under the door and is exposed outside. Now, because we have a humidifier on our HVAC system (see recent thread about moisture on windows), we have a moisture build up on the windows which trickles down to this sill which remains at close to outside temperatures (below freezing). Creating ice.
Does this sound right? Why would a door be designed to have a sill that brings in such extreme conditions? Seems they should have redesigned the sill and use a material that was less conductive to these temps or put a break in it with different material...something!! Is there any fix for this? Could I have missed something on my install?

 

Your right on the money. Alot of window companies try to sell sliding windows becasue they push them off as the dame price of double hungs and even casements but they cost much less. And the simple answer is that sliding windows are NOT an effeicent design since they have to be able to slide, the only thing sealing the panes are basically felt strips. The aluminum sill you have is another great transfer'er of heat and esspecially cold, that's why in our northern climates they never install aluminum/steel windows in residential anymore, wood and vinyl are the better choices since it wont radiate the outside climate the way metal does.

Try to turn down your humidity level in you HVAC , you want mositure but you dont want it condensating on your windows, this will lead to sill rot inside and you dont want that.

As far as the Anderson line, I'll keep my opinons to myself. But sooner or later people around the country-especailly in winter regions-are going to start talking to each other and find their problems are universal and why the #1 windows often replaced are Anderson. Not to mention the consistent problems they have when shipping out custom orders and replacement parts, maybe that's just with our Home Depot store, but Millwork here hates working with them...but since it's their job they have to grin and bear it even though future problems will almost always surface.

 

The first thing you must do is move out of Buffalo!!! (Only kidding...my daughter put up with the Buffalo winters for 5 years)

I live near New York City and my Andersen door does exactly the same thing when temperature gets below 15 degrees and my humidity level inside the house is high. I think "IHI" has the right explanation.

 

Any time the temperature of a door or window surface reaches or drops below the dew point for that particular mass of air and its given humidity, condensation will occur.

When that temperature drops below 32F, the condensation will freeze.

This will happen with a wood threshhold as easily as with an aluminim one especially at temperatures near or below zero as found in the northeast all last week.

Couple that with the great possibility that you installed a door that was not rated for energy efficiency for your climate, and condensation will be the rule, not the exception.

(For Buffalo, all doors and windows should have a minimum U factor of .35 or below, and all doors sold in the US must be for their overall U factor...But that does not mean that all doors sold through your local suppliers need to meet that minimum U factor...It is up to the installer to ensure that the windows and doors he installs meets the minimum energy code U factor of .35 or less...)

All that said, it is entirely possible you installed doors that do not meet minimum requirements for your region, and even if they do, that does not mean you will never have condensation. U factor is a average or total energy efficiency of the door or window unit and while some parts may fall below average and be less efficient, other parts may fall above minimums and be more energy efficient.

Simply put, you can have glass that exceeds minimums and a threshhold that falls below minimums but as long as the overall door provides the energy efficiency required by code, is perfectly acceptable to be installed and used.

Bottom line, at 1degree F, SOME condensation is almost sure to occur on just about any door and window.