How dry is too dry? Room humidity...

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Swedishchef

Swedishchef

Minister of Fire
Hearth Supporter
Jan 17, 2010
3,275
Inuvik, Northwest Territories
Hey guys

So my stove has been running 24 hours a day for the past 4 days. My basement humidity has reached 30%. I have a humidifier running constantly (albeit at a low rate) and I burn about 1-2 gallons of water a day.

How dry is too dry?!?!

Andrew
 
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Very dry is when your hardwood boards shrink and leave gaps, your skin dries out and you find yourself applying moisturizer lotion like it's sunscreen, LOL.

Too moist and you can start growing mold in places you don't want, and your windows will be sweating a lot.

When I was running a large stove (rated to heat 2100 sqft but heating 1800) it had a 3 gal SS stock pot sitting on the top. I could cook off anywhere between 3 - 6 gallons per day depending on the firing rate of the stove + another 3 - 4 gal in the humidifier. Now that I am running an Englander 28-3500 it is a lot drier in the house, because I lost that superb flat cook top surface.
 
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I found this weather channel humidity calculator. You the current outdoor temp and humidty, current thermostat setting and it tells you what your target indoor humidty should be for good health and comfortability.

(broken link removed to http://www.weather.com/outdoors/home-improvement/humidity/)
 
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everywhere i have read says about 40-50% RH. I try to keep my place at 45%, its hard to do with the 1 humidifier have, about 2gal/day... I have an ultrasonic humidifier, using tap water it generated the "fog" "white mist" whatnot from the evaporated disolved solids, i have since bought a reverse osmosis filter and that solved all problems with the humidifier!
 
maverick06 said:
everywhere i have read says about 40-50% RH. I try to keep my place at 45%, its hard to do with the 1 humidifier have, about 2gal/day... I have an ultrasonic humidifier, using tap water it generated the "fog" "white mist" whatnot from the evaporated disolved solids, i have since bought a reverse osmosis filter and that solved all problems with the humidifier!
Click to expand...
it is a general rule of thumb. the formula is great, but i don't understand (yet) how it is helpful when adding or removing moisture. humidifiers and humidistats have percentage for settings. does somebody make a stat or porttable that works off the formula? i just have never seen one. i prefer it around 45%
 
i have 9 gal lasko recirculating humdidfier it does well! it recirculate water to keep it from growing molds or what ever the filter is cheap also 6-7 bucks for em i have to have it set up since this farm house is kinda drafty and too dry i am hitting around 35%-40% range with 2800 sug ft it supposed to go up to 3200 sq ft (broken link removed to http://www.laskoproducts.com/9-0-gallon-high-performance-recirculating-humidifier-model-1128/)
 
crossout said:
i have 9 gal lasko recirculating humdidfier it does well! it recirculate water to keep it from growing molds or what ever the filter is cheap also 6-7 bucks for em i have to have it set up since this farm house is kinda drafty and too dry i am hitting around 35%-40% range with 2800 sug ft it supposed to go up to 3200 sq ft (broken link removed to http://www.laskoproducts.com/9-0-gallon-high-performance-recirculating-humidifier-model-1128/)
Click to expand...
the more i think about it, i think i read about a humidifier with an outdoor sensor. was it a trusteam maybe?
 
its a stand alone whole house humidifier
 
I think the window is >30% for reduced winter colds and <50% for reduced dust mites. >70% runs into indoor molding issues.

The problem is that 30% RH air at 70°F starts condensing water when cooled to .... 37°F (dew point)
(calculator: http://www.dpcalc.org/)

So, if air is exiting your house into an attic, wall cavity, storm window cavity with a surface below 37°F, that surface will be wet and soaking up water all winter long.

This is why airsealing and running a small/no humidifier is safer for your house structure than running a giant humidifier in a leaky house in a cold climate. That would worry me. As it is, in an older house I would stick to the lowest value of RH I need for comfort, e.g. 30%.
 
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I just checked the little meter in our living room. 31%, 20.2°c. That's right in the middle of the red 'too dry' zone on the display. Don't think I'll worry about it though.

-19c outside this morning - brisky days are hitting earlier here this winter.
 
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Yessir.

Big blizzard supposed to hit tomorrow too. Been battening down hatches this morning before I go out for the day. I used to like winter, but not quite as much now, it seems.
 
HAha. We are not getting as much as forecast (good!) but I am sure we will get another 300-400cm before the winter is over (our average is 300-400!). Keep it south my friend, keep it south!
 
Meanwhile back at humidity...

I shot for the 45-50% mark because of some health problems. There is now all new plywood roof decking on this house thanks to the mold that exploded that year. Fortunately, kinda, it was time to replace the roof anyway.

I now shoot for 30-35%. That and I now have better attic ventilation and closed a huge mistake the builder let happen from the basement to the attic.
 
Swedishchef said:
RIght now it is 25% in my basement. I feel like my skin is about to shatter like a mirror.
Click to expand...

Sure your instrument is calibrated? Hygrometers are famously inaccurate. I don't fee uncomfortable until <20% or even notice until <30%.
 
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I have three of the two buck ones from Walmart, picked up the three that all agreed, two wireless ones and the one on the Sunbeam humidifier. They all dead on agree.

Amazed me.
 
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