Humidity Too High Even in Winter

Reply

  #1  
Old 12-17-15, 06:36 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Humidity Too High Even in Winter

Hi All.
I have a 1959 ranch house in Ohio. 1350 ft2 with full unfinished basement. Propane furnace/AC. No water in the basement. It seems to be a tight house for as old as it is. Windows were replaced about 10 years ago. They're double pane, moderate quality.

The problem I have is excess humidity. In the spring/summer if the AC is not running and windows closed the RH gets up to 65%. With AC usually 50-55%. The biggest issue is winter humidity. Right now it's at 52%. This winter hasn't been very cold so far. Our previous 2 winters were very cold. Even when it was 0 degrees outside, the humidity inside never got below 45%. This caused quite bit of water (& ice) to form on the lower parts of the windows. Many of the windows in the house now have small amounts of water damage and some small spots of black rotting wood. I'm afraid they're going to go bad.

I canít figure out why we have such high humidity in the house. We keep it at about 72 degrees in the summer and 70 in the winter. A dehumidifier is in the basement. Bathrooms have ventilation fans and we run them during & after showers. Clothes dryer is vented to outside. There is one thing about the ductwork that strikes me as odd. There are 4 registers in the basement and 4 vents in the cold air return. Is this normal? I presume they did this to help heat the basement. But itís uninsulated so itís kind of wasteful. Iím wondering if some of high humidity is because the furnace is drawing moist air from the basement and moving it upstairs?

Iím considering running a dehumidifier at night upstairs to help lower the humidity. Iíve also considered having an ERV or HRV installed, but from what Iíve seen theyíre very expensive at $2000-$4000+.

Any ideas or suggestions would be greatly appreciated. Thanks.
 
Sponsored Links
  #2  
Old 12-17-15, 06:40 AM
G
Member
Join Date: Nov 2007
Location: MI
Posts: 2,636
Received 1 Vote on 1 Post
First things first...What are you using to measure the humidity, and where?
 
  #3  
Old 12-17-15, 06:59 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
I use a digital humidity gauge in the living room
 
  #4  
Old 12-17-15, 07:14 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 9,001
Received 230 Votes on 205 Posts
You say its well insulated for the time it was built. That may be a very poor insulation package (or not). I would call a company that would do an energy audit that would include a thermal scan showing heat lose. From there you will be able to pin point areas that are letting large air exchange take place.
 
  #5  
Old 12-17-15, 07:17 AM
J
Member
Join Date: Jan 2011
Location: USA
Posts: 4,816
Received 77 Votes on 72 Posts
Air leaks around those windows can cause this issue.
Was it new constrution or replacement windows?
I just had to pull all the replacement windows out of a house we own because of all the air leaks.
Installed with no caulking on the back side of the outside stops, no foam under the bottom of the frame or to fill the gaps on the sides, one was ordered the wrong size and had a 2" gap at the top but they installed it anyway.
 
  #6  
Old 12-17-15, 07:51 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Norm-
That is a good idea. I've considered that myself. My electric co-op does this for little to no cost. They do thermal imaging and a blower door test.

Joecaption-
The house has been in my family since it was built so I know quite bit of the history (i bought it in 2009). There was a fire inside in 2003. Most of the house was gutted. All windows were replaced. I would assume they used replacement windows, but not sure. The windows that were in there before were original to 1959. I'm not impressed with the work the contractor did. Wouldn't surprise me if they were installed improperly. But, maybe I misunderstand, wouldn't air leaks cause the house to have low humidity rather than high? Cold, dry air leaking in = low humidity inside?
 
  #7  
Old 12-17-15, 08:22 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
@buckeye "wouldn't air leaks cause the house to have low humidity rather than high? Cold, dry air leaking in = low humidity inside?" you are correct. The only contribution to high humidity in your region is the reduced temperature near that window. Cold windows + more condensation. But air leakage in itself is not the cause of the higher moisture.

From your post I would thing heating an uninsulated basement could generate a lot of moisture and would give you a dry looking basement. Just from an energy loss stand point, some right insulation on the basement walls and the areas above them would be good.

You mention some of the trouble spots so obviously you have been reading. So let's do some testing to go with it. Air leakage in winter is cold air pushing into the lower portions of a home, up through the house, and out the upper leaks. If your source of moisture is from the basement it should register a fairly high RH. Of course the normal people activities will be adding to it, but it is a number that will help.

The procedure is to take several RH readings around the house and take the temperature at the exact same spot. To compare RH at different locations that may be at different temperatures we will adjust them with their dew point back to all being the same temp. Take the readings and I will walk you through the adjustment.
Temperature, Dewpoint, and Relative Humidity Calculator

By the way, I'm one of those energy auditors, only retired and there is much you can do with our guidance. A free audit with no obligations is always good.

Bud
 
  #8  
Old 12-17-15, 09:02 AM
G
Member
Join Date: Oct 2002
Location: Hamilton County, Ohio
Posts: 4,296
Received 2 Votes on 2 Posts
I would question the number of air vents in the basement. If it is not normally occupied, that is overkill. I am not sure if you are saying that there are 4 cold air return vents in the basement or if that number is for the whole house. If they are in the basement, your furnace is recirculating air in the basement without having much draw from the living area. Close all basement returns and see if you start pulling the humid air from the living area and reducing the humidity in the living area.

Just FYI, my basement is approx. 2100 sq ft with one vent and no returns. Stays close to living area temp year round.
 
  #9  
Old 12-17-15, 10:37 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Bud-

I will check some other rooms & the basement for humidity & temp. The basement does have a dehumidifier which is set at 45%. Not sure what the actual humidity down there is though. I'll check it.

Goldstar-

Yes there are 4 vents in the cold air return in the basement and 4 heat registers (all the ductwork and furnace is in the basement). I thought this seemed excessive too. And I've never seen cold air returns in an unfinished basement in other houses. I will try closing off the returns in the basement. Since these returns are closest to the furnace, I'd think they'd have the least path of resistance. So, it would draw more from these than the returns in the living space.
 
  #10  
Old 12-17-15, 10:58 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
I assume there are also several returns in the upper area, those in the basement aren't the only ones??

Bud
 
  #11  
Old 12-17-15, 11:43 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Yes. Every room except for the bathrooms has a return.
 
  #12  
Old 12-17-15, 05:55 PM
E
Member
Join Date: Jan 2007
Posts: 23
Received 0 Votes on 0 Posts
Are you running the vent fans when you shower, bath and cook? Each activity would release a large amount of water vapor into the air and in a tight house, make it difficult to get out (quickly).

Any other sources of humidity such as an aquarium or kerosene heater?
 

Last edited by enigma-2; 12-17-15 at 05:58 PM. Reason: spelling
  #13  
Old 12-18-15, 04:55 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Enigma-

Yes we run the vent fans in the bathroom during and for about 15 minute or so after a shower. As for cooking, I don't have a vent to the outside for the stove. I do like to cook/bake so I'm sure that is a contributor to the humidity.

No aquariums or ventless heaters. Do have some house plants though.
 
  #14  
Old 12-18-15, 05:03 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Bud-

I took some temp/humidity readings this morning. Here's what they were:

Bedroom 1- 70 deg, 51%
Bedroom 2- 68 deg, 52%
Living Room- 70 deg, 47%
Basement- 66 deg, 47%

The basement has a dehumidifier set at 45%. It was 30 deg with 71% RH outside this morning. And there was a small amount of condensation on the wood below the upper window pane.

Also- I blocked off the cold air returns in the basement last night. Will see if that makes a difference.
 
  #15  
Old 12-18-15, 06:04 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
"I’m wondering if some of high humidity is because the furnace is drawing moist air from the basement and moving it upstairs?"
I think that is exactly what is happening.
I've adjusted each of your readings to 70į
Bedroom 1- 70 deg, 51% ==>51% @ 70į
Bedroom 2- 68 deg, 52% ==>45% "
Living Room- 70 deg, 47% =>47% "
Basement- 66 deg, 47% ==>41% "
outside - 30į @ 71% ====>16% "

As you can see, when that outside air is warmed up, it is very dry and your basement is where a lot of it enters. Yet the basement, even with the dehumidifier running, is still 41%. That basement air is more than half of the air you get upstairs, normally, and with the 4 registers and 4 return vents, even more.

IMO, you are experiencing a lot of moisture through those basement walls and floor that is being evaporated before you see any signs of it. Normal "people" activity adds a lot of moisture, thus the need to vent after showers and be careful of other moisture activities. But when the moisture content in the air starts at 41% you are doing well to get the numbers you have.

Your furnace has been adjusted for the air flow to include the 4/4 in the basement so you may want to watch for extra cycling after you close off all or most of the vents and returns in the basement. If you close them all down there and shut off the dehumidifier (temporarily) you should see the RH spike.

Assuming it would, then you are left with reducing the moisture level in the basement.
Do you have a sump pit?
Is the landscaping around the house sloped well away from the foundation?
Are all gutter/leaders draining well away?
Is dryer in basement, check to be sure it hasn't become disconnected?

You ca always reverse these changes to get through the winter if the basement becomes way too humid, but at least you will know where to target your efforts. The good news is, insulating the basement could help the moisture (rigid foam on walls) and reduce your heating costs.

Lots to discuss, air sealing the house and ducts are on the list, but moisture management first.

Bud
 
  #16  
Old 12-18-15, 07:00 AM
J
Member
Join Date: Oct 2015
Posts: 52
Received 0 Votes on 0 Posts
Sounds like you've been going through the same thing I have, and your house pretty much sounds like mine *except my basement is finished & insulated.

Since you mentioned tight house, make sure any natural draft appliances are venting properly. I don't know anything about propane, but I can tell you that in my (kind of tight) house, ONLY when the bathroom fan is running, my natural gas naturally drafted water heater WILL backdraft & release exhaust right back in the basement instead of up the chimney.

The products of combustion include a lot of H2O. There were two windows in the basement which seemed to always be dripping wet (all windows in the basement used to be wet already). I discovered the backdrafting seemed to always hit those windows & shoot up the humidity. Leaving those windows cracked, the backdrafting does not occur & I have not seen any condensation on basement windows yet and we've had a couple days in the teens.

My basement used to float around 65% RH humidity @ around 65F with no dehumidifier running. Obviously I'm increasing ventilation by introducing dry winter air in to reduce humidity, so now the RH humidity sort of modulates with the level of precipitation with minor variance in temperature. Cracking a window, which encourages air leaks seems to contradict the energy efficiency stuff, but this has helped reduce humidity on the main floor with no measurable energy penalty after gas bill analysis.....however, I DON'T heat the basement but I'm sure my ductwork is leaky enough to introduce basement air into the HVAC system. Free ventilation!
 
  #17  
Old 12-18-15, 07:52 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Bud-

Thanks. I too agree the basement is the main culprit. To answer your questions-

Do you have a sump pit? No sump. House has natural drainage that goes around the house. There is a floor drain in each of the 4 corners of the basement. Basement never has any visible water except if we have a large amount of rain in a shot time. Then some water does seep in through the mortar in some of the corners & pool on the floor. There is definitely moisture pushing in through the mortar in other spots since a lot of it is crumbling. I've repaired some, but more pieced continue to fall off. One other thing about the basement- the walls began to buckle a long time ago. A basement company installed steel I-beams vertically on the walls to stop this. The beams are bolted to the floor joists and sunk into the concrete floor.

Is the landscaping around the house sloped well away from the foundation? I don't think it slopes either way. Looks level.

Are all gutter/leaders draining well away? I think they drain fine. The downspouts drain into a tile underground. Never seen any water bubbling back out.

Is dryer in basement, check to be sure it hasn't become disconnected? My dryer is upstairs. It does vent outside.

In regards to insulation, do you know what r value is recommended? How do you attach it to the walls?
 
  #18  
Old 12-18-15, 08:09 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
jpritzen-

This is an interesting thought. My propane furnace vents through PVC. There is a pipe that the flue gasses goes outside through and another pipe that it draws air in from the outside. On the outside, there is combo pvc exhaust/vent thing. It's kind of hard to describe but the gasses come out the middle and it draws air in back behind where the gasses vent out. I think it's closed system so I don't think it could back draft? I'm no expert though so could be wrong.

My basement has junky single pane 1950s aluminum windows. They sweat excessively all winter- both the glass & aluminum. They fog up in the summer too when it's really hot & humid outside. I might try your suggestion to crack one or two open a bit.
 
  #19  
Old 12-18-15, 08:34 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
Your furnace is sealed combustion so will not backdraft. How do you heat your water. If naturally drafted gas, it could also be a concern. Easy to test. Have someone turn the hot water on while you are down there. It should spill when it first starts up, but should establish a draft within 30 to 60 seconds. A tissue makes it easy to see which air is flowing. This assumes a gas water heater with a draft hood just above it.

Just want to add while I'm here. but a tight house will still exchange about 1/4 of the inside air every hour. Target for air sealing is usually 1/3. A traditional older home that has not been extensively air sealed will exchange 1/2 of its air. Those numbers describe why most homes experience dry conditions in the winter.

Bud
 
  #20  
Old 12-18-15, 09:10 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
My water heater is electric.

I'm surprised by your numbers on how much air exchanges outside. I would've thought it'd be much less than that.
 
  #21  
Old 12-18-15, 10:35 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,795
Received 8 Votes on 8 Posts
What size is your dehumidifier? Also basement temp?
 
  #22  
Old 12-18-15, 11:22 AM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,514
Received 37 Votes on 34 Posts
When we do a blower door test we get an idea as to how tight a house is and few existing homes can be considered tight. The target that has been used for years is 0.35 air changes per hour, less than that and they start recommending additional ventilation. BTW, high humidity is also an indication of a tight home, but I feel your humidity levels are due to an unknown source of moisture. Currently thinking it is the basement.

If you close some or all of those 4 supply registers in the basement and turn off the dehumidifier, how high does the RH go down there?

Bud
 
  #23  
Old 12-19-15, 08:19 AM
J
Member
Join Date: Oct 2015
Posts: 52
Received 0 Votes on 0 Posts
If you have a sealed combustion furnace & an electric water heater, then you don't need to worry about backdrafting - this only comes into play when gas burning appliances are unable to obtain the natural draft needed to exhaust properly.

FWIW, my house is a 1950s single story brick house and had a 0.2 air changes/hour reading on the blower door. When he kicked the blower door on, we literally heard the windows compressing. This was why my water heater backdrafted when the bathroom fan was on, but doesn't when some windows are open.

In a tight house, I think that when humidity gets in the air, since the air doesn't ventilate as much, the things within the house start picking up on that humidity, like the walls, wood floors & furniture, etc...so even if you increase ventilation, the furniture is still releasing humidity back in the air & you can't expect to get an accurate humidity number until some time passes.

Concrete is a big sponge & there's moisture in the soil below grade. If there's no outlet for the moisture to dry out, in a tight basement that can kick up the humidity. I think this was my issue because I too was looking for things that are generating moisture, placing hygrometers all over the basement & could not identify a single area that had significantly higher moisture than the rest. That just left me with the conclusion that lack of ventilation in a tight house, moisture from the concrete foundation, and the higher moisture levels on the main floor since that's where our "living" takes place just mixing in with basement air via poorly sealed duct work is the likely reason why I had high moisture, that opening a couple windows in the basement seemed to fix.

PS: Just as a disclaimer, I am not a pro - just someone with his own issues & sharing my experience and my own hypotheses based on what I've learned.
 
  #24  
Old 01-19-16, 09:32 AM
B
Member
Thread Starter
Join Date: Mar 2015
Posts: 12
Received 0 Votes on 0 Posts
Been awhile since i last posted here so I thought I'd give an update.

I took the dehumidifier out of the basement and put it in the living area. I set it to 35%. It's been keeping the room it's in and adjacent rooms at 35-40%. The bedrooms, which are down the hall from it, are 40-45%.

In the basement I cracked open a window just a tiny bit. The humidity down there has been staying 45-55% with no mechanical dehumidification.

It's been cold out lately- near 0 in the mornings, teens & 20s in afternoon, & I still have some moisture on the window panes. But nothing near as bad as before. So I haven't solved the problem but have put a band-aid on it.

I've looked at an ERV or HRV but they're ridiculously overpriced. I've thought about cutting a hole in the cold air return and running a small duct from the return to outside. This would draw cold, dry air into the furnace and disperse it throughout the house. I could put a damper in it to control how much outside air is drawn in. Would this even work? I know it would decrease efficiency but even if it cost me say a $100 more per yr to heat, it would still take 20 years to break even with the price of a $2000 ERV.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: