Condensation on windows

[wptski]

I had all my old aluminum windows replaced with vinyl Low-E, gas filled type.

Here in Michigan we've had some pretty cold nights the last few days. I noticed water droplets in the bottom corners of the unmovable panes but "not" the sliders.

My humidity was 45-47%. I have a dual input therometer with K-type bead probes which I taped to a corner on the pane. I also have a logging hydrometer which calculates dewpoint, both can download to a PC.

When the night time temperatures drops below 20F, the surface temperature of the glass in the corners goes below the dewpoint! Bingo!!

All I can read about Low-E glass surface temperature states that it should be 40-50F higher than the outside temperature. Mine are about 20F higher in the corners but the center of the pane is 13F warmer. This means that the cold temperature is being transfered through the vinyl frame. Not sure about all this sales talk or are not all Low-E vinyl windows the same.

The information I read from the glass manufactures sites but what happens when they are installed in a frame, etc?

All tempertures taken were compared with a thermal imager and agreed.

I dropped my humidity to 40% but that didn't help. I drop it to 35% now but last night it didn't get that cold.

I've search here and found threads that said that it's not the windows but if they aren't doing what their supposed to, well?

[WhoIsThat?]

There are much easier ways for salespeople to make money than to deal with knowledgeable customers!


If it's a material breach of contract or substantially violates "implied merchantibility" you might have a case.

[wptski]

Some have been replaced already because of marks, smudges, finger prints inside the thermopanes. Mostly visable in direct sunlight. I'm not done with that issue yet but since the sun isn't hitting the questioned ones because the time of year, I'll have to resume in the Spring! The factory rep has been dodging me so far on this issue.

[WhoIsThat?]

Let's say the manu. of your windows is named "PleaseGoAway".
You could try a Google search of

"implied merchantability" PleaseGoAway

and/or

"implied warranty" PleaseGoAway

and/or

"class action" PleaseGoAway

and/or

"v. PleaseGoAway"

and/or
marks OR smudges OR finger prints "PleaseGoAway"

The use of quotes is important in Google. Using Advanced Search may save you time.

Writing to your state's attorney may also help. Your tax dollars have already paid his/her salary.

If the condensation damages or can damage your house structure or trimwork, I'd certainly mention that.

If you measure outside and inside air temps and glass temps, and glass area, you can confirm or disprove their advertised conductivity.

[rayr]

I bet that they are not Pella or good Anderson. Not the Depot ones either.

[wptski]

I bet that they are not Pella or good Anderson. Not the Depot ones either.

They are Republic Windows sold at commercial lumber yards and in my case, a large installer in Michigan and Ohio.

The window builder, I'm sure doesn't make the glass. On a window that has three sections or two sliders, the center of the large center is 13F warmer in the center compared to a corner. The slider which is about half the size is 8F warmer in the center compared to a corner but that corner is warmer than the center pane's corner!

[homersodyssey]

Have you considered installing a HRV?

[wptski]

Have you considered installing a HRV?

Why to cover up a window problem? Charts that show glass surface temperatures for single, double and Low-E show mine to be barely in the double if not the single range!

[homersodyssey]

I'm a heating guy so can't speak to window manufacturing defects. However, if your home has a tight envelope you could benefit from a HRV from a health standpoint and maybe fix your condensation problem as a bonus.

[wptski]

I'm a heating guy so can't speak to window manufacturing defects. However, if your home has a tight envelope you could benefit from a HRV from a health standpoint and maybe fix your condensation problem as a bonus.

The house was built in 1956, so it's not tight. It would be like trying to keep a bottle from sweating when removed from the fridge.

I've seen several charts on line that show at 20F outside temperature the inside glass surface should be close to 60F with Low-E glass and I'm getting 40F. Either they are lying because it's done in a lab and not the real world or I have a window problem. I think the latter.

I was going to ask my neighbor who had the same windows install earlier than me but no need now! I could easily see a fogged border on one the other night.

[DanW13]

Your ID RH maybe alittle on the high side, try gettinh the RH down to 38%-40%. The other items you might want to look into is air leaks around the windows and thru out the entire home as by reducing the infiltration will lessen the need for Humidity in the home and will also lessen the condensation on your windows and other surfaces thru out the house. My home which is alot older than yours is kept at about 38% RH and my humidifer rarely runs but at the sametime is very comofrtable with no condensation on my windows even if the ID RH reaches the high 40's. Those vinly windows IMO are probably low builder grade vinly windows, Are they insulated inside the vinly framing of the windows ? Is there any type of rubber seal around the permiiter of the glazing to give the thermal paynes a thermal break from the cold air when the cold air hits the glazing ? I would suppect you have some issues to deal with on your own as well as with the window manufacutrer. What type of satisfaction guaratee did they offer or do offer if not completely satisfied once they have been installed ? that maybe your only out aside from a long and lenghy court battle. Next time you may wish to skip the vinly windows and go with a aluminum clad wood windows where you will spend alittle more money but you will indeed get what you pay for.

[wptski]

Your ID RH maybe alittle on the high side, try gettinh the RH down to 38%-40%. The other items you might want to look into is air leaks around the windows and thru out the entire home as by reducing the infiltration will lessen the need for Humidity in the home and will also lessen the condensation on your windows and other surfaces thru out the house. My home which is alot older than yours is kept at about 38% RH and my humidifer rarely runs but at the sametime is very comofrtable with no condensation on my windows even if the ID RH reaches the high 40's. Those vinly windows IMO are probably low builder grade vinly windows, Are they insulated inside the vinly framing of the windows ? Is there any type of rubber seal around the permiiter of the glazing to give the thermal paynes a thermal break from the cold air when the cold air hits the glazing ? I would suppect you have some issues to deal with on your own as well as with the window manufacutrer. What type of satisfaction guaratee did they offer or do offer if not completely satisfied once they have been installed ? that maybe your only out aside from a long and lenghy court battle. Next time you may wish to skip the vinly windows and go with a aluminum clad wood windows where you will spend alittle more money but you will indeed get what you pay for.

My RH is around 35% right, so the next time it gets that cold again, I'll see.

I watch the installers stuff insulation around the inside of the windows before they fasten them down. Before the outside trim pieces were installed, they used a Great Stuff-like foam around any openings which is supposed to have a real high R value, I forget the value I was told. I remember cut-aways showing the spacer with insulators, etc. that the salesman had.

It's just that all the info that one can find about Low-E glass generally states the same inside surface to outside values. If there's a problem at 18-20F@40% RH and even if I'm at 35% RH, what happens at 10F or less if the inside surface is only 20F higher??

I've had nine panes replaced already and two panes twice already because marks, etc. inside the thermopanes. These problems really show up in direct sunlight but I'll have to wait till next spring to resume it So, yes there is a guarantee.

[Carnak]

bay windows are prone to sweating, keep drapes drawn increases the risk of sweating

A u-shaped condnesation pattern at the bottom will be common

The high R-value of the glass is based on the centre of the pane

Sometimes you have a vinyl or wood framed window but the spacer between the panes is metallic so it short circuits the heat loss. corners lose heat in two directions

I used to tell my customers back home when it was below freezing set the ventilation system to try for 35%, better windows the higher RH you can maintain

windows tell you when you need more fresh air

[wptski]

bay windows are prone to sweating, keep drapes drawn increases the risk of sweating

A u-shaped condnesation pattern at the bottom will be common

The high R-value of the glass is based on the centre of the pane

Sometimes you have a vinyl or wood framed window but the spacer between the panes is metallic so it short circuits the heat loss. corners lose heat in two directions

I used to tell my customers back home when it was below freezing set the ventilation system to try for 35%, better windows the higher RH you can maintain

windows tell you when you need more fresh air

No bay windows and drapes are open too.

Even using the center of the panes higher temperature, it still would be 20F lower than charts list for Low-E glass.

What happens to your RH with all this fresh air?

[Carnak]

fresh air in the winter lowers the RH in the home, and therefore lowers the dewpoint inside of the home.

Assume the window has a center of the glass rating of R3

It is 20F outside and 70F inside

An estimated surface temperature is 58.7, and you would not see the centre of the glass sweat until you had about 67% RH, the frames and the corners will be colder for reasons already stated and condensation tends to be a U-shaped pattern at the bottom, because it is colder at the bottom corners and indoor air likes to flow up

[wptski]

fresh air in the winter lowers the RH in the home, and therefore lowers the dewpoint inside of the home.

Assume the window has a center of the glass rating of R3

It is 20F outside and 70F inside

An estimated surface temperature is 58.7, and you would not see the centre of the glass sweat until you had about 67% RH, the frames and the corners will be colder for reasons already stated and condensation tends to be a U-shaped pattern at the bottom, because it is colder at the bottom corners and indoor air likes to flow up

Your assuming that winter air is always dry and that isn't always so. It's 65% RH at 36F right now outside and my inside RH is 35%.

By the time condensation forms in the center of these windows at 67%, it would be running by the buckets from the corners! Nobody will be worried abount "when" the center sweats, only where is starts to sweat.

If they are rated at the centers, they must also go by size and location too. The sliders corner temperature is 5-6F higher than the unmovable pane and the center's temperature is 8F warmer than the corner. Seems like these glass specs are a bit twisted to sound good.

[Carnak]

Relative humidity is a confusing term it is relative to the temperature.

36 F & 65% RH is the same moisture level as about 70F and maybe 19% RH

Cold air is dry even at high humidity levels, the colder it is the dryer it is

[Carnak]

By the time condensation forms in the center of these windows at 67%, it would be running by the buckets from the corners! Nobody will be worried abount "when" the center sweats, only where is starts to sweat.

it will be typically a U-shaped patttern

[wptski]

Relative humidity is a confusing term it is relative to the temperature.

36 F & 65% RH is the same moisture level as about 70F and maybe 19% RH

Cold air is dry even at high humidity levels, the colder it is the dryer it is

Right, warm air holds moisture and cold air doesn't. That why RH rises at night when the air cools.

[wptski]

it will be typically a U-shaped patttern

Who cares what shape the pattern is? I had beads of water in the corners at 40% RH with 20F outside, at 67% RH, the corners would be dripping.