Exhausting Moist Garage Air

[pigpen23]

I just read this thread (https://www.garagejournal.com/forum/showthread.php?p=8116606) and have similar but different questions.

I have a heated attached 3.5 car garage and in the winter the snow and ice obviously melts off our vehicles. I also like to wash the vehicles in the garage which on occasion leads to excessive moisture in the air that is hard to control with a dehumidifier. This creates lots of condensation on the windows and on the garage doors.

What I'm wondering is if I can install two higher CFM bathroom ceiling fans ducted to the outdoors to remove the humidity in the air and keep the windows from fogging up? Or maybe a larger exhaust fan would work better? Any ideas would be appreciated.

 

[RustyJunk]

Ceiling fans even on low will keep air moving and help to dry up moisture.

 

[2011laramie]

I like using the broan 508 (exact number unsure) through the wall exaust fan. Clean and effective. Mine pull so good it pulls the garage doors away from the seals and I see a gap around the door. Almost need another fresh air duct with a negative pressure damper.

http://www.broan.ca/products/filter/utility-fans-f660c662-31af-4187-9c5f-1e90afeb612e

 

[Jackfre]

Check out Tjernlund.com They have products for this.

 

[pigpen23]

Ceiling fans even on low will keep air moving and help to dry up moisture.

I should have mentioned that. I have two ceiling fans that are generally on all winter and they actually do a very good job of drying the floor. Don't do much to help with the condensation on the windows though.

Thanks for the replies so far everyone, I'll look into your ideas.

 

[rlitman]

Condensation on the windows means that the windows aren't insulating well enough.

 

[pigpen23]

Condensation on the windows means that the windows aren't insulating well enough.

The condensation on the windows is mainly from when I wash vehicles in the garage.

 

[Showkey]

Condensation on the windows means that the windows aren't insulating well enough.

Possible ^^^^^^^ .......but not the real cause. If the air in the garage is 70-80% relative humidity and the window is 30-45* moisture will condense. It like try to stop an ice tea glass from sweating on hot humid summer day.

If the outside temps are -10* the windows will sweat when indoor is 30-40% relative humidity. Your not going to stop the icing. There are dozens article on home window icing. That’s when a fans blowing air over the windows helps by warming the window glass. Similar to taking the ice out of the ice tea, the glass will condense less or stop sweating.

Tracking and measuring the garage temperature and humidity levels is important to get a a handle on the problem.

This is a never ending battle when your bringing gallons of water and pounds of ice/snow in every day. Pushing the water/ice/snow immediately and floor drains are the only real solution. Floor drain management and freezing is another issue.

Ceiling fans dry the floor.......but only raise the humidity level in the garage, fans do NOT remove humidity they move humidity.

Exhaust fans work and hopefully the make up air is cold and dry. So the heater will run a lot more. So that becomes a vicious circle and can get expensive. High air exchange rate defeats the insulation it’s like having the window or door open.

Dehumidifier work only when they are used in warm temperatures, cold temperature operation they very inefficient. In some situations would have to emptied daily.

Often the solution is keeping the garage just above freezing. The cars really do not benefit from the heat. There are many prior discussions merits or problems of warm wet garage and long term a corrosion. If your working in the same parking spot the heat becomes more important.

 

[pigpen23]

Possible ^^^^^^^ .......but not the real cause. If the air in the garage is 70-80% relative humidity and the window is 30-45* moisture will condense. It like try to stop an ice tea glass from sweating on hot humid summer day.

If the outside temps are -10* the windows will sweat when indoor is 30-40% relative humidity. Your not going to stop the icing. There are dozens article on home window icing. That’s when a fans blowing air over the windows helps by warming the window glass. Similar to taking the ice out of the ice tea, the glass will condense less or stop sweating.

Tracking and measuring the garage temperature and humidity levels is important to get a a handle on the problem.

This is a never ending battle when your bringing gallons of water and pounds of ice/snow in every day. Pushing the water/ice/snow immediately and floor drains are the only real solution. Floor drain management and freezing is another issue.

Ceiling fans dry the floor.......but only raise the humidity level in the garage, fans do NOT remove humidity they move humidity.

Exhaust fans work and hopefully the make up air is cold and dry. So the heater will run a lot more. So that becomes a vicious circle and can get expensive. High air exchange rate defeats the insulation it’s like having the window or door open.

Dehumidifier work only when they are used in warm temperatures, cold temperature operation they very inefficient. In some situations would have to emptied daily.

Often the solution is keeping the garage just above freezing. The cars really do not benefit from the heat. There a prior discussions merits of warm garage and long term a corrosion. If your working in the same parking spot the heat becomes more important.

Thanks for your insight. I'll agree that during the winter months, there can be a small amount of condensation on the windows, but it generally stays near the edge. The windows on the garage doors never have this issue.

The windows completely fogging up when I spray off/wash vehicles is the humidity I'm talking about getting rid of. I keep the garage at 50 degrees in the winter because I do use it as a workshop as well. I do squeegee excess water to the floor drain to dry the floor quicker.

I'm not too concerned about paying for the extra gas to heat the garage when utilizing an exhaust type of fan. It's not like the exhaust fan will be running constantly. I maybe wash the vehicles bi-weekly.

 

[pigpen23]

I like using the broan 508 (exact number unsure) through the wall exaust fan. Clean and effective. Mine pull so good it pulls the garage doors away from the seals and I see a gap around the door. Almost need another fresh air duct with a negative pressure damper.

http://www.broan.ca/products/filter/utility-fans-f660c662-31af-4187-9c5f-1e90afeb612e

That is what I was originally thinking of doing. Would be relatively inexpensive and wouldn't be a very difficult installation to install one or two of these.

Check out Tjernlund.com They have products for this.

They have some interesting products. This item looks like it may do the trick. https://www.amazon.com/dp/B003VZH2SY/?tag=atomicindus08-20

They have an adapter that attaches to two 6" flexible ducts that I could run to intakes in the garage and have it exhaust outside. Plus you can switch one fan around if you wanted to bring in fresh air if I ever needed to.

 

[rlitman]

Possible ^^^^^^^ .......but not the real cause. If the air in the garage is 70-80% relative humidity and the window is 30-45* moisture will condense. It like try to stop an ice tea glass from sweating on hot humid summer day...

Perhaps. But here's my experience.

Every winter, when it's 10F out or so, I'll put a stock pot on the stove and boil off maybe a gallon to keep up the interior humidity.

The two argon filled Low-E windows in my kitchen closest to the stove never have ANY condensation on them from this. But the double-pane glass on my back door and the window in the laundry a room away both get plenty of condensation.

Looking with a thermal camera at glass is difficult (you get lots of reflections), but still possible. What it reveals, is that the interior surface of high efficiency glazing will be pretty close in temperature to the interior air temperature, whereas on builder basic windows, even double-pane, the glass inside will be maybe halfway between the inside and outside temperatures. And that makes a huge difference when it comes to condensation.

 

[Showkey]

Perhaps. But here's my experience.

Every winter, when it's 10F out or so, I'll put a stock pot on the stove and boil off maybe a gallon to keep up the interior humidity.

The two argon filled Low-E windows in my kitchen closest to the stove never have ANY condensation on them from this. But the double-pane glass on my back door and the window in the laundry a room away both get plenty of condensation.

.

I have a wall for windows that are 40’ long 10’ tall in great room they are Low E, argon, coated etc.

Winter cold weather is the indoor humidity gets too high compared to the outside temps that might be +20–30* the glass will condensate. If the blinds or curtains are closed the condensate is much worse because the glass temperature drops below the dew point. Moving air over the glass keeps the glass temp above the condensing point (aka dew point).

The indoor humidity is a moving target relative to the indoor and outdoor temperatures.

It’s the reason it’s critical to measure the humidity.........when the humidity, condensation, sweating, wet walls, mildew and mold questions comes up on the home handyman shows, they say what is the indoor humidity levels.

Whole house air changers are very common in new builds to resolve many of the issues.
The garage or basement air exchanger mentioned post #4 has merit.

That moving target humidity levels see the chart on the air exchanger controller: