what causes condensation to build up in my garage? I live in midwest & weather isn't extreme. The garage is not insulated or heated. I am tired of the rust on my tools. anyone know how to cure it?
Thanks Rob
Most of the time, you drive you car in the rain, bring in a large warm car in to a cooler enclosed area and you get condensation. Leave the door open or provide some sort of ventilation.
Temperature differential and moist air. The garage is probably cooler than the outside air right now. You bring in the warm outside air, close the door and the moisture condenses. Leave the door open longer or heat the garage a bit.
Meantime, protect your tools with something like Top Cote, Boeshield, etc.
I don't park im my garage, i have too many tools in there. :o) it's pretty much ajuys ta shop & storage, besides, my car is a company truck. :o)
You need to ventilate or heat it. Even spot heating with a light bulb will help. You need to keep the temperature of your tools above dewpont. Greg
ummm what's the temperature of "dewpoint" ?
Or use an exhaust fan with a differential humidistat.
Nick
It's a moving target. It is the temperature where the humidity hit's
100% If your tools are below that temperature, even if the air is warmer, the moisture will condense on the tools.
Dew collects on grass when the grass temperature is less than the dewpoint temperature of the air near the grass (which increases with increasing humidity.)
Condensation appears on a tool in a garage when the tool temp is less than the dewpoint of the garage air near the tool.
If you stir a glass of water with an ice cube with a thermometer, it reads the dewpoint temp of the ambient air when condensation (dew) first appears on the outside of the glass.
Td = Ta/(1-Taln(R)/9621), approximately, with temperatures in absolute Rankine degrees and RH R in fractional form. For instance, 70 F (Ta = 70+460 = 530 R) air at 50% RH (R = 0.5) has Td = 530/(1-530ln(0.5)/9621) = 510.5 R, ie Td = 510.5-460 = 50.5 F.
Nick
Longshot,
Be careful of ventilation. If the humidity ratio outside in grains of moisture per pound of air is higher than the humidity ratio inside the garage, you will not make things better. You would do yourself a favor to add some heat instead. Also, don't use a kerosene heater or some other UNVENTED fuel burnung heater, they add a lot of water vapor to the air. If you have a cabinet that you keep your tools in, you can add a heat lamp or a couple of light bulbs to warm the air inside the cabinet. If the tools hang on a wall, a couple of heat lamps aimed at the tools should help. Be careful not to get the lights too close to wood or other flamable materials as you could start a fire.
Stretch
For any given amount of moisture in the air, dew will form at a specific temperature. The more moisture in the air, the higher the temperature where it will begin to form. It varies directly with the ambient humidity.
Look at the weather report for your area on any given day and see what the dewpoint is reported to be; it'll be different every day. Then keep your garage warmer than that number.
As a pilot, I've always been leery of flying to an airport where the temperature/dewpoint spread was two degrees or less; fog is almost always going to be a consideration. It doesn't take much for a forecast to be off a couple of degrees... just enough for the temp and the dewpoint to become one and the same. The result for me: poor visibility. For you: rusty tools.
In the winter, the slab gets very cold. In spring the outside air gets warm (which holds more moisture), but the garage and especially the slab is still cooler (which holds less moisture). If the cool slab does not make it condense (like on a cold drink), the temperature drop at night can.
Thanks, that cleared it right up! Greg
The machining guys say that a fan to keep the air moving does the trick. I have not tried it yet.
RJ
Unbelievable, a correct answer, and provided by people who may not even know what dew point is. :) If the tools are at the same temp as the adjacent air, then they will never be below dew point . Toolboxes also work wonders.
hvacrmedic
R degrees = F degrees + 460.
R = RH/100.
In an amazing coincidence, F degrees = R degrees - 460... and "ln" is the natural log, the inverse of the "e-to-the-x" key on a Casio fx-260 solar scientific calculator ($8.76 at Wal-Mart.)
You are welcome. Now what's the dew point above with 60% RH?
Nick
You got me. 23?
i think i should just replace my rusted tools. :o)
Nonono. The dew point temp goes UP with increasing RH.
You DO have a Casio fx-260 solar scientific calculator, no?
R degrees = F degrees + 460.
R = RH/100.
With RH = 60%, R = 0.6, so Td = 530/(1-530ln(0.6)/9621) = 515.5 R, ie Td = 515.5-460 = 55.5 F.
Nick
PS: The price of a standard basement Humidex is $1095, installed. Loren says they have a 1 year performance guarantee, ie you can get your money back after 1 year if you don't like it. And she says it works better in houses with AC. But moving air from near the basement floor upstairs would be more efficient than moving it outdoors and moving more outdoor humid air indoors, in a house with AC.
Nick,
The humidex is one of the dumbest ideas that I have seen in years. I went to their web site and found it is a basement exhaust fan. It sucks cool air conditioned air from the house, through the basement and then blows it outside. Now the house is under a negative pressure and outside air will come in to the house to replace the exhausted air.
If the humidity ratio of the outside air is lower than the humidity ratio of the basement air, there is no point in getting the house air involved, it would be better to blow basement air outside to be replaced with dry air from outside. You may as well run the AC with the windows open. Or run the heat in the winter with the windows open.
If the humidity ratio of the outside air is higher than the basement or crawlspace air, you are adding a lot of moisture to the house and adding load to the AC system, increasing electric bills in the process. You could start growing mold in the house. The Humidex just moves the problem from the basement to the house. Bad Idea.
Buy a dehumidifier instead. In humid climates the Humidex is a disaster about to happen. In dry climate areas, it is just a waste of money.
Stretch
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