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Opinions on Insulation Value of Double Paned Patio Doors

Opinions on Insulation Value of Double Paned Patio Doors


  #1  
Old 09-04-13, 01:03 PM
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Opinions on Insulation Value of Double Paned Patio Doors

I am replacing a patio door with one fixed full view panel, and one inswinging door with full view panel. Original to the house, the current set appears to be single paned and my wife complains all the time about the cold during the winter.

At two different box stores, I priced the replacement. I believe the brands were Feather River, Andersen, Jeld Wen, Pella, and Reliabilt. All but Pella were spec'd with "low e double pane glass." The Pella came with Argon filled glass.

The price differences, even discarding the very expensive Pella unit, were significant, ranging from $600 to $1600. Now I understand that different quality materials, manufacturing methods, and warranties account for much of this difference; no questions there.

My question is whether there would be any differences in the INSULATING qualities of the glass panels in the different units. If I buy foam or fiberglass, I can see an "R" value printed on the product packaging. However, none of the manufacturers of these doors provide any similar value for the insulating qualities of the glass panels. It is either intentional, or there is no difference among them, I guess.

Anyone know anything different?
 
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Old 09-04-13, 01:20 PM
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If you go with an energy star rated door you will get the best R values for your door. It is more than the glass, it is the construction of the frame and door body as well. Some of the more expensive models (Anderson and Pella) use a vinyl clad construction in which wood is wrapped by vinyl. Results in a more solid door. But if it qualifies for the energy star rating you should be OK. Low e and Argon I believe are more effective in hot sunny climates.

Residential Windows, Doors and Skylights : ENERGY STAR
 

Last edited by czizzi; 09-04-13 at 01:35 PM. Reason: Add Link
  #3  
Old 09-04-13, 04:08 PM
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About eight years ago I had my French doors and one window in a bathroom replaced. I specified triple-pane with argon filled low-E construction. The job was five grand. The old door had dual pane glass but you got cold standing in front of it. The new door has roughly 50% more glass area and I never feel cold standing in front of it.
 
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Old 09-04-13, 04:26 PM
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A knowledgeable salesman would be able to tell you the u-value of the glass package on the units you are looking at. They should have a value for their plain glass... for their low-e package and then they usually have a high end low-e2 argon, april fresh, glass package. Usually when a customer can see the value of upgrading the glass it makes the choice easier. The closer the u-value is to zero the better. So a .27 is better than a .30 and a .30 is better than a .36.

No self respecting salesman will give an r-value on glass because it's a misleading figure. Glass loses energy so you want a number that tells you what the RESISTANCE is to heat loss. If you were in Texas or Arizona, you'd probably be more concerned with heat gain in the summer, which is the SHGC figures, which I won't get into. (solar heat gain coefficient).

I won't say all glass is created equal, but generally, you should compare a low-e price to another door with a low-e price. Not comparing clear glass to a price that includes low-e2 and argon.
 
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Old 09-04-13, 04:50 PM
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I'd like to make a few observations about the "Energy Star" rating, just to get it off my chest.

Energy Star is a good benchmark. IMO, it was established to help people who are confused by a lot of numbers. Someone picked a "mediocre" u-value and SHGC and said that minimum standard is good enough for all/most climates in the US and/or Canada, which really is kind of misleading in a way. A person could think that if their glass meets Energy Star qualifications that it's a good window/door and that it won't frost up in the winter. That couldn't be further from the truth.

You could have 2 windows/doors that both have energy star stickers, and one could theoretically be 40% better than the other. But to the average customer, if they look the same, you would think they were equal in quality- after all, they both have the sticker. The only way you would know the difference is to look at the u-value statistics mentioned earlier.

Energy Star is, in a way, a method used to dumb down the figures for people who don't understand or know how to interpret them. It has its place though as a minimum standard, so I'm not knocking it.
 
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Old 09-04-13, 05:19 PM
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Thanks for the info. Let me make a few observations:

a) The only argon model I looked at was Pella, and the price for my application was about $2800, with their 15% promotion applied. My objection to the Pella unit was first price, as I'll never see the full payback (leaving this home in 5-6 years); second, the proprietary hardware, which the sales person said I could not buy separately (I have another identical set of doors --- not being replaced at this time --- 15 feet away on the same wall. Would like the hardware to match).

b) I had forgotten that it was the U value, not the R value but no door I received quotes on displayed a U value. As far as a "good salesman" would know the U value, I agree, but hey --- I'm shopping at Lowe's and Home Depot. I feel I've run into an expert if they can actually bring the doors up on their computers..

c) I am Zone 7 (Northern Virginia) but the door is on a north facing wall --- it never receives any direct sun at any time of the year.
 
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Old 09-04-13, 05:35 PM
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You've lost me XSleeper. R is just the reciprocal of U, so the two are just inversely related. My two cents worth, and I am no expert, is that glass insulating values rise as the separation of the panes increases, but only up to an inch. Beyond an inch, convection currents set in and insulating value drops.
 
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Old 09-04-13, 06:07 PM
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Correct, Handyman. What I was referring to are the snake oil salesmen who say that "their window" boasts an R-13, and just as warm as an insulated wall. (Which is pure BS... as they are lying through their teeth, or at the least, stretching the truth about one small component of a window) If a window is 90% glass, and the glass has a u-value of .30, tell me how they get R-13 out of that?

Anyone that talks about r values when talking about windows is blowing smoke, unless they are giving the REAL r-value of the total system, which, if the u-value is .25 would be R-4.

Salesmen don't like to say their window is R-4 because in the mind of a customer, that would be very COLD compared to their R-13 wall. In actuality, a window that is R-4 is a pretty darn good window. It's just that the consumer hasn't been educated to know that.
 
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Old 09-05-13, 05:59 AM
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Again, it is more than the glass. You can have a premier pane of glass, but if you install it in an aluminum frame, you will have a crappy overall unit.

Most doors will be put up and secured through the frame and brick moldings added. Pella and Anderson offer doors with nailing flanges that can be sealed with window wrap and don't need a drip cap to keep water out. A sealed door nailing flange will also cut down on drafts. Pella has a 3 point locking system that you can get that would better apply positive pressure against weather stripping as an option. If you have operated both the high end doors and a standard door, there is a world of difference. Is it worth the extra money? I sometimes find it hard to justify. Kind of like putting $2000 rims on a $500 beater car. Your house will dictate what the upper limit should be. Anderson has a 25 year warranty on their glass.
 
 

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