A LOT of condensation on widows and sills

[teddy bear]

Thanks for all the replies. As for the first question, I do not have any fresh air ventilation system. As for the second question, I am built on a slab, so no crawlspace or basement. Also, as I stated in my original post, it seems that when the heater kicks on, the humidity in the house shoots up all of a sudden. I just don't understand this. How much does the ultra-aire 70h cost and how much would it cost to have it installed? Thanks again, everyone.

Chad

Bingo!
Try this for a theory.
The duct board exterior surfaces in the attic are below the dew point of the air in the home during evening hours. During the cold evenings, the attic and duct surfaces cool, moisture from the air in the home condenses inside the ducts on the cold surfaces of the duct board in the attic. While heating, the ducts warmed, the condensed moisture is evaporated and blown into the home. This raises the indoor humidity rapidly.
I suggest operating the fan in the "on" mode enough to avoid the ducts from cooling below the dew point of the air in the home is currently +50^F. With ducts in a cold attic, you need to keep the duct surface above the dew point of the air in the home. The fact remains that you are not getting not getting enough fresh air into your home, but may not beable to avoid some condensation in attic ducts during cold weather. Operating you blower in "on" mode low speed on the coldest evenings will eliminate the considensation on the inside of the exterior duct surface of the ducts in the cold space.
A clue to the amount of fresh air naturallly infiltrating your home. Four occupants in the 2,200 sqft. home should get 80 cfm of fresh air when the home is occupied at a minimum. This will purge indoor pollutants, renew oxygen, and keep the indoor dew +10^F above the outdoor dew point. Currently, your area is 50^F outside dew point. Expect the indoor dew point to be 60^F. At 75^F inside, expect 60%RH. The dehu will run a little to maintain <50%RH. When the outdoor dew point drops below 40^F, the dehu should not run if you are getting 80 cfm of fresh air passing through your home.
Operate you fan "on" mode for a couple days to test "the condensation in the ducts" theroy.
Keep us posted. Operating a bath exhaust 24/7 will also increase ventilation to reduce winter moisture problems.
Most important is to keep the fresh air moving through the home during the calm warm times of the year to purge the indoor pollutants and renew oxygen. Unfortunately, you will need more dehumidification when the outdoor dew points are high. It is a small cost to pay for good indoor air quality.
This is an excellent learning opportunity. Keep us posted.
Regards TB

[tipsrfine]

What TeddyBear said about running the fan in the "on" position is what the manual recommends also. Unico manual. If you're going to do that I would ask a contractor about whether or not you can replace the blower motor with an ECM motor. These motors are way more energy efficient than PSC motors, especially when in the lower "continuous" setting.

[BamaCool]

A LOT of condensation on widows and sills.........Just curious...How many widows live with you? Maybe they're just sweating profusely because you made them widows!!

[clllclal]

A LOT of condensation on widows and sills.........Just curious...How many widows live with you? Maybe they're just sweating profusely because you made them widows!!

Good one! As many times as I've read this post, I've never noticed that "n" not being there.

[clllclal]

Bingo!
Try this for a theory.
The duct board exterior surfaces in the attic are below the dew point of the air in the home during evening hours. During the cold evenings, the attic and duct surfaces cool, moisture from the air in the home condenses inside the ducts on the cold surfaces of the duct board in the attic. While heating, the ducts warmed, the condensed moisture is evaporated and blown into the home. This raises the indoor humidity rapidly.
I suggest operating the fan in the "on" mode enough to avoid the ducts from cooling below the dew point of the air in the home is currently +50^F. With ducts in a cold attic, you need to keep the duct surface above the dew point of the air in the home. The fact remains that you are not getting not getting enough fresh air into your home, but may not beable to avoid some condensation in attic ducts during cold weather. Operating you blower in "on" mode low speed on the coldest evenings will eliminate the considensation on the inside of the exterior duct surface of the ducts in the cold space.
A clue to the amount of fresh air naturallly infiltrating your home. Four occupants in the 2,200 sqft. home should get 80 cfm of fresh air when the home is occupied at a minimum. This will purge indoor pollutants, renew oxygen, and keep the indoor dew +10^F above the outdoor dew point. Currently, your area is 50^F outside dew point. Expect the indoor dew point to be 60^F. At 75^F inside, expect 60%RH. The dehu will run a little to maintain <50%RH. When the outdoor dew point drops below 40^F, the dehu should not run if you are getting 80 cfm of fresh air passing through your home.
Operate you fan "on" mode for a couple days to test "the condensation in the ducts" theroy.
Keep us posted. Operating a bath exhaust 24/7 will also increase ventilation to reduce winter moisture problems.
Most important is to keep the fresh air moving through the home during the calm warm times of the year to purge the indoor pollutants and renew oxygen. Unfortunately, you will need more dehumidification when the outdoor dew points are high. It is a small cost to pay for good indoor air quality.
This is an excellent learning opportunity. Keep us posted.
Regards TB

What TeddyBear said about running the fan in the "on" position is what the manual recommends also. Unico manual. If you're going to do that I would ask a contractor about whether or not you can replace the blower motor with an ECM motor. These motors are way more energy efficient than PSC motors, especially when in the lower "continuous" setting.

Thanks for the input. I will try that. So I set the heat to setpoint and when the temp. is satisfied, the heat will cut off but the fan will continuously blow? Take for instance at this point in time. The temp. outside is going to get around 72 degrees today. It will not be hot enough for the A/C to run or cold enough for the heat. Should I still let the fan run?

Thanks again everyone

Chad

[energy_rater_La]

Chad,
before you write us all off...
try what teddy bear suggests:
Operate you fan "on" mode for a couple days to test "the condensation in the ducts" theroy.

personally...I'm not sure about that, but would be interested in what you find out. as teddy bear
says..its a learning experience.
better to resolve what is happening than to live with it...right?
investing a week of your time may provide a solution to your RH issues.

living in the south...I've seen the issues caused by the whole chinese drywall fiasco.
corrosion of copper in electrical, hvac causing homes to be re-wired, hvac system completly
changed out...breathing issues. its nothing to make light of.


keeping the thread on track is always difficult. so just ignore what doesn't apply & use
could help you. insulting homeowners is not the intent of this forum.


best of luck

[teddy bear]

Thanks for the input. I will try that. So I set the heat to setpoint and when the temp. is satisfied, the heat will cut off but the fan will continuously blow? Take for instance at this point in time. The temp. outside is going to get around 72 degrees today. It will not be hot enough for the A/C to run or cold enough for the heat. Should I still let the fan run?

Thanks again everyone

Chad

This condensation will only occur when the attic temp is below the dew point of the air in the home. Sun on the attic roof or warm outside temps mean a warm attic and no condesation potiential in the ducts. No need to run the blower when the attic is +65^F.
Regards TB

[clllclal]

This condensation will only occur when the attic temp is below the dew point of the air in the home. Sun on the attic roof or warm outside temps mean a warm attic and no condesation potiential in the ducts. No need to run the blower when the attic is +65^F.
Regards TB

One more quick question. My tstat gives the option for "on" or "circulate." Which one would you recommend I use?

Thanks

Chad

[tipsrfine]

Circulate. You may want to keep the dehumidifier running until that ductboard dries out.

[energy_rater_La]

a building science article that in part addresses what is going on is Chad's house.
only part of the article...see picture #4

http://www.buildingscience.com/docum...rces/retrofits


Photograph 4: Window Condensation - Interior moisture levels go up due to reduced air change and relative humidity adjacent cold window surfaces rises sufficiently to condense water. How to fix this problem? Lower the moisture content of the interior air with dilution ventilation or warm up the surface of the windows by replacing the windows with better windows or do both.

So Far:
1-reduced Rh by adding dehumidifier
2-are the kitchen vent fan & bath fans vented out of the attic?
3-leaving fan set in on position..in case there is condensation in the duct work. as per Teddy Bear's postings.
4-windows...see my first post about metal frames of windows & condensation.

also...while letting the blower run in winter to resolve the issue of moisture in ductwork that is potentially ongoing,
the side note to that is fan setting in the summer.
for cooling season when a/c use is constant, you set the fan to auto.
reason for that is...RH removed by a/c will collect on coil, when fan is set
to on position...it releases this moisture back into the house when compressor cycle ends.
when fan shuts down as unit shuts down, the moisture then is released to the pan
and drains away.

so...are your kitchen & bath fans vented out of the attic??

best of luck.

[clllclal]

a building science article that in part addresses what is going on is Chad's house.
only part of the article...see picture #4

http://www.buildingscience.com/docum...rces/retrofits




Photograph 4: Window Condensation - Interior moisture levels go up due to reduced air change and relative humidity adjacent cold window surfaces rises sufficiently to condense water. How to fix this problem? Lower the moisture content of the interior air with dilution ventilation or warm up the surface of the windows by replacing the windows with better windows or do both.

So Far:
1-reduced Rh by adding dehumidifier
2-are the kitchen vent fan & bath fans vented out of the attic?
3-leaving fan set in on position..in case there is condensation in the duct work. as per Teddy Bear's postings.
4-windows...see my first post about metal frames of windows & condensation.

also...while letting the blower run in winter to resolve the issue of moisture in ductwork that is potentially ongoing,
the side note to that is fan setting in the summer.
for cooling season when a/c use is constant, you set the fan to auto.
reason for that is...RH removed by a/c will collect on coil, when fan is set
to on position...it releases this moisture back into the house when compressor cycle ends.
when fan shuts down as unit shuts down, the moisture then is released to the pan
and drains away.

so...are your kitchen & bath fans vented out of the attic??

best of luck.

The kitchen is not. I'm not sure about the three bathroom exhaust fans. Looking in the attic above where one of the fans are located, there is a vent pipe that exits the roof, but this might just be for plumbing. Could the exhaust fans be tied to that. I know I'm not very much help on this. Shame on me for not knowing more about my own home. At the very moment, I am running the fan in the "on" position with my stand alone dehumidifier running full blast.

[energy_rater_La]

I never vent bath fans thru the roof. they just don't have enough 'push' to go up and out.
instead I vent into soffits. you can tell which joist bay has venting because you'll see light from
outside.
you'd have to first...find the bath vent fan, if its covered with cellulose, turning it
on will help you to locate it. if it has a backdraft damper..or not...it will blow the cellulose
around..helping you to find it.
backdraft damper needs to be installed so that when fan is off, the damper closes.
suprising the number of bath fans that the bd damper is installed incorrectly.

usually bd dampers are the same size as dryer vents. I use a foil flex dryer vent
attached to bd damper. lenght of venting will easily reach into soffit, cutting off
excess vent. you want to keep the vent run as straight as possible.
I use mastic tape to attach venting to damper, then damper to bath vent fan.

code also says that bath fans are to be vented out of soffits. but to go
from venting into attic to venting into soffit suffices for existing homes.

bath fans & stove fans that vent into the attic introduce a lot of humidity into attic.
when bath fans vent directly into insulation they can over time cause mold growth.
stove vents vented into the attic put grease particles in the attic.

a fireman once told me that the cause of a lot of attic fires was from
stove vents terminating in the attic and not being vented outside of attic.
codes dictate this, but in existing homes...we get away with a lot more than new construction.


at this very moment...I'm consitering turning the a/c on. 75 degrees with 70% RH outside today!

[tipsrfine]

One may get away with "cutting corners" by trying to vent bathroom exhaust out of the attic soffits in hot climates, but it should NEVER be done in the colder climates. This is especially true if you have your attic air sealed and improve the insulation levels. What happens is that the air sealing & improved insulation makes your attic colder - because it is no longer being warmed by your homes conditioned air leaking into the attic- and all of that warm moist air that you think you are "venting" through the soffit is simply being drawn back into the attic, where is condenses on the cold roof. As seen in this video, it can lead to some serious problems.
http://www.youtube.com/watch?v=pne-iMqVfOY