There is an interesting condensation pattern on the inside of the double-pane window.
Even though neither side of the plastic (vinyl?) grids between the two panes directly touch either pane, the grids still affect the R-value near them (lowering it).
Outside temperature was below freezing; inside temperature at the thermostat was about 70F.
I don't think your indoor humidity is too high.
I'd think it was due to a less than perfect seal in the windows.
I thought he was getting ready for a winterland photo shoot.
Hi, Circulate air in the house take in some fresh air. You can run the furnace blower until windows are defogged. No option to run the blower at low speed all the time?
^^^^^^^
I think you're wrong. BTDT.
What seal? His windows have *INTERNAL* grids. They're decoration only.
Ok I think I read it wrong, when he said "inside" I thought he meant "inside the windows" . Then it probably is a humidity problem but most humidifiers are adjustable so ti should be an easy fix.
Actually, it happened at all 10 double-hung windows in my house. They are all from the same manufacturer, but I doubt every one would have an imperfect seal. Even if the seals were imperfect, why would the condensation show up in that pattern? And as I said the first sentence, the condensation is on the inside of the inside pane, not between the panes.
Hi, Ron furnace blower. circulate indoor air taking in sosme fresh outside air. If you have humidifier, lower the setting. Fogy window is not good for the health of window. Our house is equpped with triple pane Argon filled windows. I set humidistat at 25 to 30% during winter time.
The thermostat has an ON position that forces the fan to run all the time. (Can't control the speed, however, from the thermostat.) But that would create a chilly draft when the furnace isn't producing heat and waste electricity. Also, two of the bedrooms are unused. I have their ceiling supply registers closed and I keep their entry doors closed.
The humidity is added at the furnace by an Aprilaire unit. I have to manually adjust the setting as directed by a decal on the control panel that relates outside temperature to a dial setting. You can get the idea from here if you zoom the photo and look at the upper right corner of the control unit:
While the temperature is controlled closed-loop via the thermostat, there is no closed-loop control of the humidity via a humidistat tied into the Aprilaire unit.
I simply changed the Aprilaire setting to eliminate the problem. I posted the photo here just as an education into the obscure behavior of windows, even double-paned ones.
Thing like that happen in really cold weather. If you measure the temperature of the indoor side of the glass it is below the dew point. Aside from "below freezing" there is little to go on. Pick up a hygrometer and find out what the humidity is as a starting point.
Hmm, Have you ever done na energy audit? And look into running blower at lower speed when you only need air circulation? I modified furnace control and thermostat to do that. At lower speed you don't even feel the draft. Sounds like your house may need to soup up the insulation wherever it may need. Between furnace cycle if there is too much temp. swing, that is one indication. Ideally indoor temp. should be kept near constant at set point. In winter our 'stat is set at 21 deg. Celsius. Temp. indoor is maintained between 20 and 22. Hardly feel any draft between furnace cycles.
When this happened to my Dad, he put a block of wood under the tank, screwed the wood to the deck (up from under). Then, perforated strap over the top of the tank.
Of course there is a closed-loop control. The humidistat that's mounted on the furnace plenum that you're adjusting maintains the humidity at the level you set, just like the thermostat maintains the temperature.
When it gets colder outside, you have to lower the humidity level to avoid condensation. Or you can get one of the better Aprilaire that have an outdoor temperature sensor that does it automatically.
Nothing really obscure there, it happens all the time when it gets cold enough outside and humid enough inside. They are just panes of glass separated by a small gas filled space. The window glass is going to be significantly colder than your walls that are filled with 6" of insulation.
You can do all that and if you have a humidifier with the humidity level set too high for the outside temp, you're still going to have the same thing happen. Max indoor humidity should be 45% max when it's around 40F outside. When it gets down to 0F, it should be about
20% max. When you see condensation like that, back the humditiy setting down....
...
The other thing is that these humidstats are notoriously inaccurate with age...there's no telling what it is actually responding at as compared to the actual indicated setpoint. A secondary humidistat could indicate just what actual range of RH is.
pane window.
Everyone is making a simple thing as compicated as rocket science, just tur n the humidity down when it gets REALLY cold!!!.
Agree. They are even inaccurate right out of the box. Many, probably most of them, don't even have the dial calibrated by humidity. They just have 1 to 7 or whatever. I think the one the OP posted the link to is exactly like that.
Bottom line, if you have one of these and it doesn't have automatic compensation via an outside temp sensor, you either have to adjust it when the temp drops real low, or else set it lower and leave it lower even when it's 40F outside. Otherwise, you can expect condensation problems. That's why I bought the Aprilaire with the outdoor sensor.
Not so happy with this one either. Overall, I think they make great products. But the LCD display started failing on this one when it was just 2 years old. Display is shot now, but it still controls the humidity, you just can't see what the humidity actually is.
Condensation is formed when cold comes in contact with hot as you probably know. Whether it's on the inside or outside of the window pain is irrelevant. It means you have a problem with your windows.
Most double pain windows are filled with argon or krypton gases to slow the transfer of heat through the window; however, after an extended period of colder exterior temperature, the material ultimate achieves homeostasis from the outside pane to the inside pane: BOOM! condensation.
What you need is new windows.
Even the BEST window will form condensation on the inside if the RH is high enough on the warm side and it is cold enough out side. There is heat loss even from the BEST windows. If you know the "dew point" of the inside air, at THAT temperature on the window surface you will get condensation. If you get FROST on the inside of the window either you have a window problem or it is EXTREMELY cold outside.
If I REMEMBER right, the OP said he had to TURN DOWN the adjustment on FURNACE humidifier which WAS TURNED up a bit MUCH.
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