Ice on the Windows!

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I live in a suburb of Chicago, It is around -3 degree Fahrenheit, I wake up this morning and found ice on all of my bedroom and kitchen windows. What does this indicate? Do I have leaky windows? I kept humidifier (aprilaire - attached with my furnace) to 35%.
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DONT PANIC! the weather is extreme, are your windows dual pane?
in any case the humidifier is causing this its normal so dont worry about it.
with higher humidity you can keep the thermostat lower:)
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And LOSE money.
Nick
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Nick, what do you suggest to make the air comfortable to breath if not a humidifier?
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snipped-for-privacy@ece.villanova.edu wrote:

Are you talking about the money it takes to put the water into the air? Thats really not all that much.
--
Thank you,



"Then said I, Wisdom [is] better than strength: nevertheless the poor
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It's about ten times the lowered thermostat savings :-)
Nick
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I read one of the posts mentioning that when outside temperature is too cold you should change the humidifier setting to around 25%. But I have aprilaire automatic humidifier (model 600) and it says that computer controlled and has been installed right before return air enteres into the furnace. Do I still have to adjust the humidifer settings?
Thanks in advance
Original Poster
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wrote:

Keep the air around 50% for the best comfort. This is also best for furniture and electronic equipment. Twenty-five percent is very dry. Cooler air holds less water than warmer air. Converting liquid water to water vapor requires adding lots of energy. Cover ting solid water (ice) to liquid water requires energy, but not nearly as much. You can increase humidly by using vaporizers or lots of plants.
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Sounds about normal for that combination of outdoor temperature and high humidity. Try setting it a bit lower if it is a problem.
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These windows are new..they are thermopane windows (double pane windows) I was just curious because they were new and might have start leaking
Thanks for your reply
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If there wood windows I would be wiping out the moisture when the ice melts,so the wood does not have to be re-stained or painted, keep the drapes or blinds closed when the temp gets into the single digits. I think that ice build up when the temps dips to single digit is inevidenable, the only way to cure this is with a storm window, outside the new windows, that would reduce the glass temp on the inside of the house.
A humidity guage would be nice to see what the actual humidity is in your house.
I have the same problem and do not run the power humidifer in the winter and still have what is considered normal humidity in the house in the winter months. I do wipe out the water as needed and about every 3 years re-finish the lower wood sill of the windows. My windows are thermopane.
Tom

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I've seen this happen much more than usual when people close the shades at night, particularly if the shades are insulating type. You need to get the warm air to flow up and over the glass. If so, just cracking open, or opening completely, the shades while you sleep will greatly reduce the amount of ice that builds up by morning.
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And LOSE money.
Nick
Ahh the heat loss is the same at 10% humidity or 50%
BUT!
The occupants will be more comfy at a lower temperature, with higher humidity.
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Not really, since evaporating water takes energy and houses leak air. To raise indoor RH AND reduce the fuel bill, caulk the house.
Nick
Newsgroups: alt.home.repair Subject: Re: Winter humidification wastes energy Date: 11 Feb 2005 08:33:11 -0500 Organization: Villanova University
Sent: Monday, January 17, 2005 8:58 AM
Subject: Attn: president/legal--Winter humidification wastes energy
Gentlemen,
I suspect that winter humidification wastes vs saves heating energy, and the savings claim is an energy myth. People tend to forget that evaporating water takes heat energy, and that heat energy has to come from somewhere, even if something like a humidifier belt motor uses little energy by itself.
The heat saved by turning a thermostat down appears to be far less than the extra heat used to evaporate water, in all but extremely tight houses with little insulation, eg submarines.
http://lennox.com/pdfs/brochures/Lennox%20WB2-WP2%20Humidifiers.pdf claims that 69 F at 35% RH and 72 F at 19% RH are equally comfortable, but the BASIC program in the new ASHRAE 55-2004 comfort standard predicts that 69 F and 35% RH and 69.7 at 19% RH are equally comfortable (PMV = -0.537, see below.)
If a 2400 ft^2 tight house has 0.5 ACH and say, 400 Btu/h-F of conductance, turning the thermostat down from 69.7 to 69 saves (69.7-69)400 = 280 Btu/h.
Air at 69 F and 100% RH has humidity ratio w = 0.015832 pounds of water per pound of dry air, so 19% air has wl = 0.00301, and 39% air has wh = 0.00617. Raising 69 F air from 19 to 39% requires evaporating wh-wl = 0.00316 pounds of water per pound of dry air. Dry air weighs about 0.075 lb per cubic foot.
With 0.5x2400x8/60 = 160 cfm or 9600 ft^3/h or 720 pounds per hour of air leakage, raising the indoor RH from 19 to 39% requires evaporating 720x0.00316 = 2.275 pounds of water per hour, which requires about 2275 Btu/h of heat energy, so it looks like humidifying this fairly airtight house wastes 2275/280 = 8 times more energy than it "saves." And many US houses are less airtight, so humidification would waste more energy.
Please modify your energy-savings claim.
Thank you.
Nick Pine
10 SCREEN 9:KEY OFF 20 CLO=1'clothing insulation (clo) 30 MET=1.1'metabolic rate (met) 40 WME=0'external work (met) 50 DATA 69,35,69.74,19 60 FOR CASE=1 TO 2 70 READ TC,RC 80 TA=(TC-32)/1.8'air temp (C) 90 TR=TA'mean radiant temp (C) 100 VEL=.1'air velocity 110 RH=RC'relative humidity (%) 120 PA=0'water vapor pressure 130 DEF FNPS(T)=EXP(16.6536-4030.183/(TA+235))'sat vapor pressure, kPa 140 IF PA=0 THEN PA=RH*10*FNPS(TA)'water vapor pressure, Pa 150 ICL=.155*CLO'clothing resistance (m^2K/W) 160 M=MET*58.15'metabolic rate (W/m^2) 170 W=WME*58.15'external work in (W/m^2) 180 MW=M-W'internal heat production 190 IF ICL<.078 THEN FCL=1+1.29*ICL ELSE FCL=1.05+.645*ICL'clothing factor 200 HCF.1*SQR(VEL)'forced convection conductance 210 TAA=TA+273'air temp (K) 220 TRA=TR+273'mean radiant temp (K) 230 TCLA=TAA+(35.5-TA)/(3.5*(6.45*ICL+.1))'est clothing temp 240 P1=ICL*FCL:P2=P1*3.96:P3=P1*100:P4=P1*TAA'intermediate values 250 P508.7-.028*MW+P2*(TRA/100)^4 260 XN=TCLA/100 270 XF=XN 280 EPS=.00015'stop iteration when met 290 XF=(XF+XN)/2'natural convection conductance 300 HCN=2.38*ABS(100*XF-TAA)^.25 310 IF HCF>HCN THEN HC=HCF ELSE HC=HCN 320 XN=(P5+P4*HC-P2*XF^4)/(100+P3*HC) 330 IF ABS(XN-XF)>EPS GOTO 290 340 TCL0*XN-273'clothing surface temp (C) 350 HL1=.00305*(5733-6.99*MW-PA)'heat loss diff through skin 360 IF MW>58.15 THEN HL2=.42*(MW-58.15) ELSE HL2=0'heat loss by sweating 370 HL3=.000017*M*(5867-PA)'latent respiration heat loss 380 HL4=.0014*M*(34-TA)'dry respiration heat loss 390 HL5=3.96*FCL*(XN^4-(TRA/100)^4)'heat loss by radiation 400 HL6L*HC*(TCL-TA)'heat loss by convection 410 TS=.303*EXP(-.036*M)+.028'thermal sensation transfer coefficient 420 PMV=TS*(MW-HL1-HL2-HL3-HL4-HL5-HL6)'predicted mean vote 430 PPD0-95*EXP(-.03353*PMV^4-.2179*PMV^2)'predicted % dissatisfied 440 PRINT TC,RC,PMV 450 NEXT CASE
69 35 -.5376486 69.74 19 -.5372599
Engineering VP Mark Hogan said Lennox was embarrassed by all this and he didn't know where their numbers had come from, and he thanked me for bringing this to their attention and said they are changing their printed brochures and Aprilaire web site energy-savings claim.
This reminds me of David and Goliath :-)
Nick
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Its condensation on your windows that is freezing. Its normal for extreme low temps. When the temp is not extremely low it will be just water/condensation on your windows.
wrote:

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c_shah wrote:

It means the dew point of the air in your home is greater than the temperatures of the inside of those windows and that that temperatures is below 32 F.
If it is just an occasional thing, it is nothing to worry about. If it happens often it will damage the windows.(the wood parts)
Correction means decreasing the humidity and therefore the dew point and or increasing the temperature of the inside surface of the window.
The first means reducing the humidity and or the air temperature. The second means maybe adding a storm window or using multi-paned windows where there are single panes now.
If you have curtains or drapes over the windows and close them at night, it will help keep the room warm, but it means the inside window surface will be colder yet the air's dew point will be the same. Increasing air circulation to the windows can help.
--
Joseph Meehan

Dia duit
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wrote:

Stick your tongue on them and find out.
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As the outdoor temperature drops, you are supposed to drop your indoor humidity. This is from the Aprilaire web site: Outdoor Temp(F) Humidistat setting(%) 40 45 30 40 20 35 10 30 0 25 -10 20 -20 15
The purpose of doing that is prevent condensation on cold surfaces (IE: windows). I had one house that had frost develop on the wallboard nail heads. OF course the indoor humidty was way too high and it was -15F outside (Chicago area)

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wrote:

No. Humidity from indoors condenses and freezes on the windows--no so uncommon. Make sure to wipe up the water as soon as it melts to prevent damage. Ideal humidity is 50%.
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occupied rooms like bedrooms will have higher humidity from people breathing.
again ice on window is nothing to worry about
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