glider/slider windows: try before you buy

Thermal performance, U-Value, and air infiltration are two different animals. I was primarily talking about the window seal and air infiltration. I just visited the NFRC site and didn't see any information on air infiltration - just U-values. Where can I find that information on that site?

It was meant to be absurd. It was meant to show that testing a system for something it was not designed for is not testing the system. I said that.

Okay...I haven't read the report. You have. I'm not sure why a testing procedure wouldn't have its specifications listed. Two week duration. That's a specification. Intermittantly sprayed water is not a specification - it's a very loose description.

Of course, but the question is, does the information have relevance for what I need a window to do?

I wrote: "I think Consumer Reports is a great publication - a great service. But unless you've edited out a lot of information in your synopsis, the results are not relevant as the test is just bizarre." I don't see how that could possibly be construed to mean I don't trust them.

I was merely asking what "severe temperature fluctuations" means. It may mean 30 below zero to 150 above in an hour - I have no idea. Both ends of that spectrum are meaningless to me in my climate. Windows are designed for longevity, trying to force a test to have failures (how else could you determine the winners and losers?) in two weeks means something fairly extreme is going on. I'd like to know specifically what the extremes are. I don't think it's really asking a lot if I am to give credence to anyone's testing procedure. The "intermittent spraying with water" also needs clarification. Spraying doesn't necessarily indicate anything at all about the amount of water and the pressure.

I don't take anything on blind faith, and I don't happen to feel that CR is an unquestionable authority. I don't subscribe to CR, so this is all I found in a quick Google:

"How to choose Performance differences. Consumer Reports has found most windows do a very good or excellent job at sealing out a fairly strong wind when the outside thermometer registers 70=B0 F. Only a handful do well at sealing out a high wind when the outside temperature drops to zero. When it's that cold, weather stripping and other components can stiffen or shrink. Our tests have shown that aluminum frames are durable. But we have found windows with frames made of vinyl- or aluminum-clad wood can perform well, too. Recommendations. If you're replacing windows, choose those that are designed for your region's climate. Cooling costs predominate in southern regions, so look for double glazing and a low-E coating. Give first consideration to windows with a low solar-heat-gain coefficient. The Department of Energy recommends that the number be 0.4 or lower."

There are specifics in that. 70 degrees vs. 0 degrees, for example. I'm more interested in the 70 degrees as the 0 degrees is a lot rarer around here. My personal experience also counts for something - at least to me. If I hit an aluminum clad window frame with a bat, in any weather, that dent will be there forever. If I hit a vinyl clad window with a bat on a 70 degree day, it won't do much of anything, while on a

I understand what you're saying.

I do think it's worthwhile to use a rule of thumb that the CR people are not doing something absurd, based on their track record. Faith? sure. Blind? no. Always correct? no. Do I sound like Don Rumsfeld? you bet.

Thanks very much for your thoughts on windows.

I've beat the internet pretty hard and can't find much information on air leakage by brand, let alone window type. According to the NFRC site, the air leakage rating is currently optional on their stickers.

It is interesting, though, that Marvin double hungs and casements, for example, have the same R-factor (2.7) and the sliders have a lower R-factor (2.33). There could be things other than air infiltration at work, of course.

Thanks. I have found a few contractors that will install whatever brand I'm interested in. The rub is, where can I see one before I buy

My research from online and factory brochures showed casements superior in air infiltration to sliders and double hung, only fixed units can surpass a casement, as I previously noted you pull a casement into its weather stripping, sliders also wear the gasket, test are on new units. For high wind areas casements cant be beat, and considering slide type seals that wear out and the fact that 50% of heat loss can be air infiltration in old units casements win every time

m R,

If you have any data on that left over from your research, I think it would benefit a lot of window shoppers to post it. In my experience, it's hard to find data on air leakage. The NFRC has a standardized rating, but I believe it's optional to report it.

I think there's some merit, qualitatively, to the argument you're making. But ultimately, people put different weights on different factors, so the magnitude of the difference is key here. As I noted, the R-factor data from Marvin is *suggestive* on this point, but not a pure measure of leakage.

Cheers

ccskr I emailed you, and will look, but alot of this I got on factory Pella Anderson and Hurd brochures, alot of company sites info online I cant access because of weby tvs limited usefullness . All major window companies have every rating for every window they make, for anderson it is hundreds of windows.

Well, anything you've got handy. Don't go doing all the research all over again! I keep beating on google, thinking surely there's a website where these air leakage and other ratings are tabulated for the major window guys, but I don't see anything like that.

Thanks again.

Does your Co detector have a digital read out and record peak readings from 1ppm, if not get one 35$. Could it be an Ng leak, there are dual types of senors for 50$. Get a pro to fix it if you can`t.

I have to get all that research back for a job but it will take time. Andersons and pellas sites have it im sure somewhere.