At room temperature how much water = 100% humidity?

Factual Questions
1

Lets say the room is 20’ x 20’, and the temperature of the room is 70 degrees F. If I could wring out all of the water in the room into a receptacle, how much water would I have?

(Let’s say the room is empty so that furniture, carpet, etc. isn’t soaking up any of the water.)

2

At 20C (68F, close enough for government work), 100% RH is equivalent to 17.3 g/m3 of water vapour (Reference).

So, a 20’ x 20’ x 10’ room = 4000 cubic feet, or 113.3 cubic meters, will contain 1960 grams of water.

1960 grams = 69 oz = 4.1 pints (US).

3

Gazing at my psych chart, I see about 0.0157 lbm water per pound of dry air, at 100% RH and 70 F.

Density of dry air at 70 F is about 0.075 lbm/cubic foot (roughly, I don’t have a table in front of me, so this is not an exact number).

So we have 20 by 20 by 10 = 4000 cubic feet of dry air.

4000 * 0.075 = 30 pounds of air.

30 * 0.0157 = 4.71 pounds of water

4

And my guess ends up as about 2140 grams. Not bad for me completely pulling a density from memory…I guess it depends on how accurate one wants the answer. One might also have to take the altitude into account for even further accuracy.

5

Per these nice folks (http://www.humirel.com/All_about_humidity-calculation4.htm) at 100% humidity at 70 degrees F the concentration of water is 19.5 grams/meter^3.
After waay too much unit conversion math, and assuming your room has an 8 foot ceiling, I come up with 0.47 gallons, or 1.87 quarts.

Funny thing was it took about 2 minutes to google to find, read about, understand, and then use the relevant humidity calculator, and then about 8 minutes to use Excel to convert g/m^3 into stupid American units via 5 steps.

6

I see I’m not too fast on the typing part either.

7

19.5 (g / (m^3)) = 0.00121734523 pound / (ft^3)

8

Thank you all for your input. (Closed circuit to LSL Guy: I regret that I’m not metric, and I appreciate your efforts. :slight_smile: )

Now I guess I can estimate how much water is being soaked up by the furniture as well as is condensing on the windows since my humidifier is set for 95% humidity and it goes through way more than 4 pints/day.

9

It’s probably much more likely that the water is being carried out of the room by your furnace (assuming central) and people walking in and out of the room then anything else. If you want to check it, get a cheapo humidistat from a pet store and see what it says.

10

Can you please help me on this?
How to calculate the amount of water needed to keep relative humidity 95% in a 20’*6.5’*8’ room at 60 degree Celsius? I just need the calculation process and the references.

Thanks a lot