Condensation on double pane windows - Help.

[netminder]

Hello I am hoping some one can help me with this problem I am having any suggestion, ideas is greatly appreciated.

I have:

-HI-efficiency furnace with its own intake & exhaust

-3" flex duct connected to the cold air return about 10' away from the furnace

-Conventional water heater which vents up the chimney

-Cold air return registry installed in the basement.

-Home is 59 years old and the windows are 20 year sold but vinyle and double pane.

The humidity is 29% according to my humidity reader, dehumidifer would not come on because it is below 35%. The ouside temperature is -20 deg C and my house temperature is set at 66 deg F.

I have lots of condensation and frost on all of the upstairs windows which is double pane and no condensation in the basement. Can some one explain why I am having this problem the humidity is low enough I cannot go any lower because it will dry out my house.

I taught it was back draft from the water heater but I don't know can anyone think of any thing.

Thanks

Richard

[Scottpat]

Is this the first year you have noticed the condensation and frost on the windows?

[netminder]

Yes this is the first year I am noticing this issue

[Steven Hockstein]

Two questions:

1. It is definitely on the inside of the windows and not between the insulated glass panes? Condesation between the panes is a completely different problem.

2. Like Scott wrote, is this a new problem? What is different in your home this year? Have you recently replaced the furnace, renovated a bathroom, new siding, etc?...

There are many potential causes of condensation and you need to provide more info to get back educated guesses.

[AHI in AR]

Have you done anything recently that would block the flow of heated air across the windows such as new window coverings that stay closed a lot?

[Rocon]

In walls the placement of the Insulated Glass Unit (IGU) needs to be placed correctly in each wall assembly. Many retrofit vinyl windows place the IGU too far outboard in the wall assembly causing cold spots near the frame. This cold spot usually is most prevalent near the frame corners where you will see a boomerang shaped area of condensation.

You have two different walls that are performing differently:

• The basement probably has less overall insulation which moves the condensation line outward and the windows are typically inset further into the walls.

• The upstairs walls are probably more thermally efficient which draws the condensation line at the windows inward.

To test my theory raise the interior temperature to 74 degrees F for 24 hours. I am assuming you are not keeping blinds or drapes closed.

[netminder]

these are the things that I did differently this year.

-I replaced my mid efficiency furnace with a HI-efficiency furnace but kept my conventional water heater

-I installed a cold air return in the basement living room, the living room is the opposite wall next to the furnace.

-I installed ceramic tiles in the kitchen and washroom upstairs.

But that being said the humidity is 31% upstair and 36% downstairs can't go any lower because hardwood would start sweaking and seperating.

Richrad

[netminder]

some windows have both inside of the windows and inbetween the window pane (the one that is inbetween the pane has always have a broken seal). I was going to replace the ones with the broken seal but the window people advise me it might not be worth it since the windows are still in good condition and may never see a return in my invenstment.

[hausdok]

It's only a hunch but it sounds to me like your upstairs return isn't pulling a whole lot of air. Once you put that basement return in, the furnace was able to get plenty of return air from the basement and you reduced intake on the upper level to the point that the air upstairs isn't as "conditioned" as it needs to be.

Do an experiment. Take a towel, wipe down those windows and then try covering up that basement return and running the system for a while to see if the condensation still occurs. If it stops, start uncovering the basement return a little bit at a time until the condensation begins again. At that point, you'll know what size opening at the basement will unbalance the system to the point where the condensation occurs upstairs. You may need to install some kind of return air damper.

ONE TEAM - ONE FIGHT!!!

Mike

[Steven Hockstein]

If you pulled the furnace flue from the chimney and are now using a direct vent system, there can now be a condensation problem within the chimney. Is the chimney on an outside wall? Did the furnace installer discuss the issues related to removing the furnace from the chimney and leaving the water heater? Not sure if this would cause problems with condensation on the windows but it can cause other problems that you should know about.

Where was the return located before you installed it in the living room?

You need to contact someone that knows about heating/air conditioning/dew points, etc..

Call one of you local home inspectors and ask to pay for a consultation. It will be a lot cheaper than repairing the damages caused by prolonged excessive moisture in the house.

[netminder]

hausdok, thank you for that reply, for some reason that makes complete sense. I am going to take a pillow and block that return vent in the basement up increase the temperature to 68 deg C instead to 65 deg C and see if the condensation reduces.

Steven Hockstein the chimney has a B style liner and is located in the middle of my house so it is kept warm until the attic, I had someone take a look at the chimney and they said every thing look fine and liner seem good but I may get a second oppinion.

[Jim Katen]

hausdok, thank you for that reply, for some reason that makes complete sense. I am going to take a pillow and block that return vent in the basement up increase the temperature to 68 deg C instead to 65 deg C and see if the condensation reduces. . . .

If you use a piece of cardboard, you'll be able to make finer adjustments.

- Jim Katen, Oregon

[Bain]

" 3" flex duct connected to the cold air return about 10' away from the furnace "

I don't understand what this is. Is this the return you installed in the basement? A 3" duct--depending on blower speed and some other stuff--will only move +/- 20 cfm of air, which is inadequate for pretty much anything.

Also, you aren't allowed to have a return-air register withing ten feet of a gas appliance 'cause it can prevent the flue gases from drafting correctly. Is the furnace drawing combustion air from inside or outside? And how close is the return to the water heater?

[Terence McCann]

Do you have a humidifier on your furnace and/or you running stand alone humidifiers?

[netminder]

Bain, The 3" flex duct hooked up to the cold air return seems to be some kind of fresh air intake, it just brings in a small amount of fresh air and mixes with the air before it is pulled into the furnace. I have a two stage HI-efficency furnace and run the fan on low 24/7

The cold air is located 5' away from the water heater but draws air from the opposite wall not the side where the water heater is mounted. I am going to take a picture and upload it of the configuration so you can have an idea of what I mean. Do you think the cold air return in the basement is causing the condensation on the windows?

[netminder]

Terence, Humidifier is turned off and water valve is closed. Humidity right now is 28% and heat inside is 70 deg C and temp outside is -17 (feels like -24).

[Bain]

Bain, The 3" flex duct hooked up to the cold air return seems to be some kind of fresh air intake, it just brings in a small amount of fresh air and mixes with the air before it is pulled into the furnace. I have a two stage HI-efficency furnace and run the fan on low 24/7

The cold air is located 5' away from the water heater but draws air from the opposite wall not the side where the water heater is mounted. I am going to take a picture and upload it of the configuration so you can have an idea of what I mean. Do you think the cold air return in the basement is causing the condensation on the windows?

Is the 3" duct drawing air from outside? If so, it may be the cause of your problem. That would be a little wacky for a residential system. It's common in commercial buildings--specifically meeting rooms and areas with lots of bodies--to better circulate and dehumidify the air, especially when the system is operating on A/C mode. But I've never seen a set-up like that in a house.

[Bain]

Also, I've never experienced -17 degree temperatures, but it may just be that it's cold as a witch's booby outside, and 70 degrees inside, and there's nothing you can do about the condensation.

[netminder]

witch's booby, hahaha

[Terence McCann]

The humidity is coming from somewhere. If you have condensation on the inside of your windows I'd also check the attic for mold.

-18C is 0F. If you have 30% RH inside the home either the whole home humidifier is running or you like cooking spaghetti - a lot.

When you say you can't go any lower in humidity because it will dry out your house what do you mean? It would appear that you can control the humidity to some degree no?

You also said: But that being said the humidity is 31% upstair and 36% downstairs can't go any lower because hardwood would start sweaking and seperating.. How can you possible keep the humidity at 36RH when it is 0F outside without a humidifier?

[netminder]

Terence what I mean by don't wan't to get any lower than 30% is that if I open all the windows in the house (air the house out) the humidity will drop to 18% or lower. But I was told to keep the humidity at around 30% if lower run the dishwasher or vent the kitchen cooking less etc to increase the humidity or maintain it. I do not use a humidifier. I was also told if the humidity is to low (less than 30%) I might have problems with my wood furnishing, hardwood floor etc.

I taught 30% humidity was good a number to be at am I wrong??

[netminder]

Hello can you all help me out by telling me the following:

-What is the current humidity in your home

-What is the temperature outside your home

-What is the temperature inside you home

I just would like to know what every one else humidty level is in comparison to minds.

thanks very much

[Terence McCann]

Hello can you all help me out by telling me the following:

-What is the current humidity in your home

-What is the temperature outside your home

-What is the temperature inside you home

I just would like to know what every one else humidty level is in comparison to minds.

thanks very much

What you're asking means nothing. John Doe lives in Jamaica - how does that relate to your conditions?

Call a reputable heating company to take a look at what is going on.

[Bain]

Hello can you all help me out by telling me the following:

-What is the current humidity in your home

-What is the temperature outside your home

-What is the temperature inside you home

I just would like to know what every one else humidty level is in comparison to minds.

thanks very much

What you're asking means nothing. John Doe lives in Jamaica - how does that relate to your conditions?

Call a reputable heating company to take a look at what is going on.

You've got to stop spewing misinformation. J. Doe moved to Eleuthera maybe . . . two years ago. Get up to speed, for crying out loud.

[Big Bill]

At my house in WI I contribute the upstairs moisture to the bathroom shower. That and the fact that the cold air returns are not quite balanced. It's an 80 year old cape cod. I also think the window and window jam are the least energy efficient insulators. The bathroom shower isn't used oftne in winter because that would instigate ice damming which is way worse than the small puddle in the ol' sill. Ya gotta love the nort' eh? bill