Window Fogging in Cold

Not directly related to PRIME fogging problem, but I wanted to know if anyone have very good suggestion for preventing condensation on windows in your house. Our house is tightly sealed for good insulation measure, but even with double pane gas filled insulated windows, we get a lot of condensation on inside of the window glass and frame around it. Comes with these moisture is the mold. I know the best solution is to install a whole house heat recovery ventilation system, but it is just too expensive. Running dehumidifier all the time also can get very costly. If I just want to prevent condensation on the windows in our house, is there any cheap and easy way???

 

I just use a throw-away dehumidifier, like Haier. They're cheap, inexpensive to operate, and, when strategically placed, can be effective at mold suppression. You can get them a Walmart.

Also, I would try to identify and reduce sources of moisture. Keeping doors closed and using vent fans in the kitchen (when cooking) and in bathrooms (after taking a shower) can go along way towards keeping moisture down.

The best way to prevent condensation in the windows is to reduce moisture at the source.

 

Thank you. All good suggestions. But unfortunately, they will not work in our situation. We have two fairly large capacity dehumidifiers. I know they do the job, but running them are like running large window unit air conditioners all day long. It is the operating cost of electricity that becomes prohibitive at our very high electric rate. Reducing source of humidity from the kitchen is another problem, our kitchen+dining+living room is open plan. No door to close. And our range hood do not vent to outside.

 

The air replacement systems with heat recovery are so interesting, and I think some even DIY them, at least in part. But yeah it can get pricey.

We got a general contractor in (must be close to 10 years back now), replaced all our drafty, seal-compromised aluminum windows with the latest. They also did a front door replacement, and blew in about an extra foot of insulation in the attic.

They also installed a new vent system in the two upstairs bathrooms: a central exhaust fan in the attic between the two bathrooms, new ceiling vents, motion sensors and a humidistat in a hallway.

Basically any time someone's in the bathroom the fan activates due to motion, and will run for 20 minutes. And on humid days, the fan will run whenever you pass the threshold set on the humidistat.

It's not as energy efficient as the whole house air replacement with heat recovery, but it's better than what we had, no humidity problems.

Too, our kitchen range hood doesn't even vent to outside. I keep thinking to do something about that, but never do. The kitchen's got vaulted ceiling, so it would be tricky.

 

Absent the pricey HRV -- which also won't work as well in houses without the ducting of central heating/cooling -- it seems that accepting the energy inefficiency of exhaust fans is just a necessary evil in order to control household moisture.

The original bathroom exhaust fans in this house were weak but horribly noisy. They had to be turned off to allow sleep. I eventually discovered that the primary one was seriously clogged and out of balance due to caked-on lint and body powder. The unbalanced vibration problem was severe enough to cut the life expectancy of the included heat lamp to merely a week. Removing the fan for a thorough cleaning fixed the imbalance portion of the noise, but it keep re-accumulating, demanding annual cleaning.

Eventually the spouse ceased with that post-shower body powder. And I replaced the inherently noisy fan with a Panasonic Whisperlite, vastly quieter and more effective at blowing air. It still needs cleaning, but less frequently, and it doesn't degrade as much when caked. That was 17 years ago, many other appliance makers now have similar products.

Later I put in programmable fan timers. These can run manually on-off, or auto-shutoff after a set time on (10-60 minutes, easily adjustable per use), or automatically cycle on-off by fixed program (10-60 minutes on, 10-120 minutes off), or all of the above together. Or it can self-program based on a few questions (bathroom size, fan-CFM rating, etc.). I don't believe this particular unit has a humidistat.

I see outside-venting exhaust over the cookstove as essential, for smoke reasons from the inevitable (at least in my household ) stove-top 'accidents'. And for moisture control. This house started with the usual weakly-sucking noise monster, finally replaced with a stronger and much quieter unit.

Quieter exhaust fans means they get used more, definitely helping reduce window condensation.

 

That's why I was suggesting that you try a smaller dehumidifier - if for nothing more than to test it for suitability and power consumption. The Haier unit that I use extracts between 2 and 3 gallons of water per day during the summer. I don't use it much in the winter, during which it only pulls about 1 gallon every 2 days, but in your case I am sure it would extract more than that. Relative humidity stays between 40 and 60 percent for a 2 bedroom apt. Locate the unit between the humidity source and HVAC inlet - in your case, either in the kitchen or immediately outside the kitchen toward the inlet. You can empty the condensed water manually, when testing it for location, and then plumb it later for continuous operation after permanent location/installation.

To get an idea of effectiveness, image boiling away 2 gallons of water in you kitchen, and how it would effect the humidity in your home if you continued that every day without dehumidifying. It wouldn't take long before you had a rain forest in your home.

These are small disposable units costing $160.00 - $200.00. I have been using one for 2 years now.

Haier 30 pint Dehumidifier HEN330ET

 

One thing bothering me with our new "central" exhaust fan. It's a long crawl through the attic, the one they pumped an extra foot of loose-fill insulation into. I've never been to check on it. Someday I guess I've gotta don a bunny suit and mask, head in there. Maybe lay down some cardboard along the way. Ugh...

 

I am not sure what is your definition of a "small" dehumidifier. I don't have specs on the two units I have at our house handy, but they both look kinda like the one you are pointing to. Not sure of how many "pints" of water removal capacity they are, but they are very similar in size to the 30 pints one your link is showing. Maybe tidbit larger, IIRC. When I had those units running they would run almost constantly as long as I don't forget to empty the tank every 3-4 hours. Having one on each floor, I remember our electricity bill was close to $100 more per month. Do this for the entire winter, it can cost quite a bit. Moreover, they are as loud as the window unit air conditioner which we don't use often enough precisely because of the noise. We prefer to be sweating in a quiet hot room than sitting in a very noisy cool room in the summertime. Fortunately, our summer is very cool. Only countable numbers of middays we wish to have an air conditioner on. Now with a dehumidifier, it will turn on day or night and all day, all winter long.

 

OK. When you said "two fairly large capacity dehumidifiers" I thought you were talking about a permanent installation. Sounds like you have a model similar to mine... ...only noisy.

The question then is "are your 2 dehumidifier sufficient in mitigating condensation on the windows?" If the answer is yes, then it still might be worthwhile to shop around for a quieter, more energy efficient unit. $200.00 per month does seem to be a bit much.

 

Yes, if run constantly, they will eliminate the humidity problems. Yeah, it may be worth looking around for a newer unit. I know they are ~10 years old, and one is probably no longer working. The last time I tried using it, the fan run, but the compressor never turned on.

edit: I looked at one that is still working. It is a Whirlpool AD40LBK0, 40 pints dehumidifier. I don't know what noise level of this unit is. Also not sure what the kWh rating. Hummm, where can I find that information?

 

Several tasks up there over the years had seriously disturbed and compressed my house's original insulation, which was the bare minimum under an obsolete code. So after the neighboring mirror image house (same builder, same time) suffered serious water damage from a frozen and burst fire sprinkler pipe while the family was away, I decided that action was necessary to protect my fire sprinklers.

The following autumn I finally fixed the whole thing. Put little cardboard 'tents' over the sprinkler pipes so that they are thermally well connected to living space below, no insulation in between. Added enough blown-in insulation to exceed not just current attic code, but current electric-heat recommendations too, more than tripling the depth of the original undisturbed insulation above the top of the pipes. And stuffed plenty of material into more than 100 square feet of discovered un-insulated ceiling, beyond the view of any normal inspections. And sealed numerous wall-ceiling gaps where warm air in the walls could flow up and out.

I haven't needed any summer A/C since. Not that this house in this moderate climate ever needed all that much before. The solar modules also help in this regard, blocking quite a bit of direct sunlight on the south roof.

 

I found a zone like that: the builders had messed up a small portion of the concrete perimeter foundation wall; it was into the living space. So they left it there, did another wall further out. Trouble was, acess to that little pocket between the two walls was difficult, and no one ever crawled through to insulate the perimeter wall through that section. Me fix.

Lot of other nightmares too, lol.

 

Ordered a 70 pints dehumidifier. Much larger than the 40 pints unit I have now, but I am hoping a bigger one will be more powerful to extract water quickly and runs a shorter time. This 745 watts unit running 6 hours/day will cost ~$25/mo. That will be cheaper than the same brand 30 pints model at 420 watts running 24 hours costing ~$60/mo. I will see how it work.

 

Yes. I did a little research on it as well. The Frigidaire is highly rated - rated best by some, with Haier as runner-up. All of the new portable dehumidifiers have significantly improved efficiency over pre-2015 models. I believe it has a continuous drain option as well, so you should be able to plumb it for continuous operation.

One caution that I had forgotten to mention earlier. When you get the unit and start to set it up, you need to heed the caution regarding setting the unit on it's side. Apparently, you need to letting compressor oil settle before use. Assuming that the unit has been on it's side during shipment, the Frigidaire requires that you leave the unit in the upright position and wait a few days before you operate. The Haire unit has the same precaution. I picked it up a Walmart where it had been sitting on the shelf, in the box, in the up-right position, so it probably would have been safe to operate straight out of the box. However, after I had assembled the unit, I chose to play it safe and let the unit sit for two days before I plugged it in.

 

Thanks for the heads up information. I knew the compressor needs to stay upright for a refrigerator and/or a freezer, so the same rule must apply to the portable dehumidifiers, but did not know how long it takes to settle down, if tipped to it's side. I ordered mine from Walmart as you did, but it is being delivered to my home. I hope they do keep it upright during the transit, but I will make sure to keep it that way for a few days before using it.

I checked the 10+ years old 40 pints unit yesterday, but it is really loud, and looks like it is on it's last leg as well. The compressor kicks in and out at abnormally high rate. And if set to AUTO it shuts off the unit completely before reaching the desired humidity. Depending on how powerful the new unit is, that is how long it needs to run on daily bases, I may order another one either bigger or smaller depending on the this one's performance to use on the second floor.

 

Sound like a plan.

'Luck.