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Dangerously Low Humidity


David Burgess
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53 minutes ago, uncle duke said:

what i can't fathom is he mentioning 78% outside and a 3% inside with no machines running or other sources for moisture enhancement.

now if there were to be a 20 to 25% reading outside there in Michigan I could believe that 3%  a little better.  I might bet Finland was in the 20% range or close for PKG but am willing to learn something new everyday too.  Yes, I can be wrong sometimes but I just hate being found to be wrong Sir{s}.

I don't live in the same town David does, so I can't verify his outside humidity reading or what the temperature was in Ann Arbor at the time of that reading... but high relative humidity outside in very cold weather here can translate to dangerously low relative humidity inside a heated building.... as Jackson Mayberry explained. There are a number of psychrometric charts available on the internet that illustrate this if you google the subject. 

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20 minutes ago, germain said:

I dropped a BOVEDA 72% in each one of my cases. The humidity in my house is about 22-24% so the boveda brings it up to 38-43% range now

I bought a giant dampit.  It was loose so I don't know what instrument it's for.  I keep it clipped in where the string tube used to be.  Keeps it between 40 and 50.  Wood case with water resistant cover probably helps a little

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1 hour ago, uncle duke said:

what i can't fathom is he mentioning 78% outside and a 3% inside with no machines running or other sources for moisture enhancement.

now if there were to be a 20 to 25% reading outside there in Michigan I could believe that 3%  a little better.  I might bet Finland was in the 20% range or close for PKG but am willing to learn something new everyday too.  Yes, I can be wrong sometimes but I just hate being found to be wrong Sir{s}.

According the the National Weather Service, the outdoor temperature when I got up this morning was -11 degrees F, and the outdoor relative humidity was 78%. My house was at 70 degrees F.

Here's one place you can plug in those numbers and play with them:

http://bmcnoldy.rsmas.miami.edu/Humidity.html

Here's another:

http://www.dpcalc.org/

 

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8 hours ago, Jeffrey Holmes said:

You don't live in  Michigan... Was -8 F where I live this morning... Inside humidity without humidifier, even factoring in cooking, watering plants, and a morning shower, would be way less than ideal.

This of course is also dependent on the heating system. For those who have a (dreaded, IMO) forced hot air system....humidity can disappear fast. Hot water systems on the other hand would hold up a lot better. 

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2 hours ago, _Alex said:

This of course is also dependent on the heating system. For those who have a (dreaded, IMO) forced hot air system....humidity can disappear fast. Hot water systems on the other hand would hold up a lot better. 

I believe this is largely a myth.  My forced hot air system performs no magic tricks.  It heats the air in my shop by passing it over a hot metal surface at a higher velocity than the air passes over the hot metal surfaces of (most) hot water systems.  Steam heating systems may vent a small amount of water vapor into living spaces, but I've not lived with or seen  one of those in 45 years so cannot say.  If I'm mistaken, please educate me.

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7 hours ago, _Alex said:

This of course is also dependent on the heating system. For those who have a (dreaded, IMO) forced hot air system....humidity can disappear fast. Hot water systems on the other hand would hold up a lot better. 

Not unless your "hot water system" is a pan of water on the stove. ;)

5 hours ago, Mark Norfleet said:

I believe this is largely a myth.

Agreed. I don't know how this myth got started... maybe by people who sell or service hot water space-heating systems?

I also haven't heard of a hot water space-heating system which can approach the energy efficiency of a forced-air condensing furnace.

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4 hours ago, GeorgeH said:

With what is happening in Texas, I was wondering if freezing a violin is less harmful than desiccating it. 

 

 

I suspect so.
I only have a few examples, but one is fairly extreme that I mentioned here a while ago.  One of my early instruments spent 30 years stored in an unheated horse barn in SE Michigan not far from where David and I live.  It would have been exposed to sub freezing temps many times.  After its owner had ended her career as an itinerant trainer of racing horses, it was brought to me to put back into playing condition.  All I had to do was glue some seams and do some regular maintenance.  It has suffered far more damage since she started playing it again.

Another customer was recently asked to play an outdoor memorial service in below freezing temps.  The pitch of the instrument was unstable at first when she took it outside.  I suggested she leave it outside until the she had to play the next evening and it stabilized and worked.  I've not seen the instrument yet, but she thinks it's fine and has had no trouble with it.  I made sure she tuned it a few times after bringing it back inside to make sure the pegs didn't get stuck.

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17 hours ago, uncle duke said:

what i can't fathom is he mentioning 78% outside and a 3% inside with no machines running or other sources for moisture enhancement.

The thing to keep in mind is that once the air temperature drops below freezing it can no longer hold much moisture and what was there falls out of the sky.  So 78% at sub zero F air temp represents VERY little moisture.

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20 minutes ago, Mark Norfleet said:

The thing to keep in mind is that once the air temperature drops below freezing it can no longer hold much moisture and what was there falls out of the sky.  So 78% at sub zero F air temp represents VERY little moisture.

i'm not going to try changing the way jeffrey, david, bruce and yourself think about humidity.

i'm checking my local weather and i see 15f outside with 86% outdoor humidity and the indoors readings here are 46% and 38% respectively.  the chart means nothing to me other than wtf, sorry.

the main point was david saying more or less be careful -  which most understood from the beginning.

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1 hour ago, uncle duke said:

i'm not going to try changing the way jeffrey, david, bruce and yourself think about humidity.

i'm checking my local weather and i see 15f outside with 86% outdoor humidity and the indoors readings here are 46% and 38% respectively.  the chart means nothing to me other than wtf, sorry.

In your situation, there could be many things going on, from an inaccurate hygrometer (more common than not), to moisture being added to the indoor space by normal household activities, like showering, cooking, or running a dishwasher.

If you'll reimburse me for shipping, I'll send you five brand-new, highly inaccurate Oregon Scientific thermometer/hygrometers for free. At least this might keep them out of the landfill for a while longer. :)

I also have a Johnson Controls human hair humidistat, which I think I paid 175 bucks for, which I'll sell you for ten bucks. Why? Same reason.

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In case it helps somebody:

We have an whole house humidifier (Aprilaire), but it did not perform adequately to keep indoor humidity above 30% on freezing days, so I had to supplement with humidifiers in rooms with instruments. 

Last fall, I switched the water feed line to the Aprilaire from the cold water pipe to the hot water pipe, and this has raised the indoor humidity by around 10%, so indoor humidity is around 35% on freezing days, and higher on non-freezing days. 

Therefore, I stopped using the humidifiers, and I keep Stretto case humidifiers in cases and my cabinet. The pads stay moist for 2 weeks plus (I soak them before they dry out), and this has solved the winter humidity problem for me. 

In my cabinet, I keep 2 soaked Stretto cello case humidifiers. Currently, the outdoor temperature is 27ºF, the indoor temperature is 71ºF, the whole house indoor humidity is 35%, and the cabinet humidity is 52%. 

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2 hours ago, Mark Norfleet said:

The thing to keep in mind is that once the air temperature drops below freezing it can no longer hold much moisture and what was there falls out of the sky.  So 78% at sub zero F air temp represents VERY little moisture.

I think your talking about two different things. Humidity, which the amount of water in the air, and relative humidity (RH), which is the percent of water in the air relative to the air's water holding capacity. I asked about whether humidity also mattered (in another conversation related to temperature variation) and I was assured that humidity itself didn't really matter, it was the equilibrium between the wood and air with respect to RH. I confess that I failed to dig any deeper into the question.

-Jim

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12 minutes ago, jacobsaunders said:

Philip hasn’t realised yet that he is supposed to be grateful :D

surely he is grateful.

where he is at is an area that is fueled by underground natural gas.  the problem is that the state of texas back in the day took no measures to freeze proof the lines thus blocking needed energy to run to other energy sources. 

the last i heard was some 3.5 million without nothing other than wood burners, assuming they have those there.  

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1 hour ago, David Burgess said:

In your situation, there could be many things going on, from an inaccurate hygrometer (more common than not), to moisture being added to the indoor space by normal household activities, like showering, cooking, or running a dishwasher.

If you'll reimburse me for shipping, I'll send you five brand-new, highly inaccurate Oregon Scientific thermometer/hygrometers for free. At least this might keep them out of the landfill for a while longer. :)

I also have a Johnson Controls human hair humidistat, which I think I paid 175 bucks for, which I'll sell you for ten bucks. Why? Same reason.

thank, but no thanks.  it's possible to get someone else to bite though - i haven't the time.

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13 hours ago, Mark Norfleet said:

I believe this is largely a myth.  My forced hot air system performs no magic tricks.  It heats the air in my shop by passing it over a hot metal surface at a higher velocity than the air passes over the hot metal surfaces of (most) hot water systems.  Steam heating systems may vent a small amount of water vapor into living spaces, but I've not lived with or seen  one of those in 45 years so cannot say.  If I'm mistaken, please educate me.

Not a myth at all. It has nothing to do with water ADDED to the air from radiators or baseboards. It is because of moisture REMOVED from the air by the forced hot air system, which is then vented outside. (A forced hot water system on the other hand only has to vent combustion gasses directly from the furnace itself.) Just because it is -20 out does not mean it is low humidity. it is only low humidity inside if your heating system is removing the moisture, which is unfortunately something that forced hot air does very well. 

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22 minutes ago, _Alex said:

Not a myth at all. It has nothing to do with water ADDED to the air from radiators or baseboards. It is because of moisture REMOVED from the air by the forced hot air system, which is then vented outside. (A forced hot water system on the other hand only has to vent combustion gasses directly from the furnace itself.) Just because it is -20 out does not mean it is low humidity OUTSIDE. it is only low humidity inside if your heating system is removing the moisture, which is unfortunately something that forced hot air does very well. 

You've got some stuff wrong. A forced air system (in heating mode) does not remove any moisture from the inside air. In one of the less efficient forced air systems, some inside air may be used for combustion, requiring that this be replaced by outside air, but this is no different from a  hot water system, or even a fireplace or a wood burning stove.

If you still wish to claim that a forced air heating system removes more moisture from the habitated space than a hot water system, please describe the mechanism by which it does so.

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