# Whole house humidifier fear of the unknown



## Billbill84 (Dec 4, 2019)

Hi all. So my 2001 furnace was installed in 2001 when the house was built. We moved in last year and in winter the indoor RH was 17-20% which is obviously low. Since then I got a large pedestal humidifier and so far this year the RH stays between 28-32% (I'm aiming for 35-40% to combat the dry air crusty nose morning boogers and hardwood flooring gaps in seeing. 
I do have a whole house humidifier on our furnace that the last overzealous owner used constantly as I can see condensation staining on the drywall in some spots, wood rot on casement window bottom sash rails. 
I planned to use the WHH this year after I cleaned the line, changed filter ect.
BUT I'm not sure now that this house's HVAC system AND the fully finished basement is properly designed to accommodate a WHH. 
My fear is:
1) Mold could be in the ducts and I don't want to reactivate it with moist air. 
2) All my duct work in basement ceiling (drywalled) is uninsulated and there is leaks as with most ducts and I don't want to be putting moist air in a subfloor (probably mold up there too!)
3) Subfloor in main level living room is ridiculously loud and squeaky almost as if the plywood is soft. I looked at the bottom of the plywood from the one basement area that shows exposed subfloor bottom and I don't see any discoloration or signs of moisture. I pulled the carpet up in the corner and it's still white from paint splash, no discoloration. My realtor said it's likely a result of the dhawdy large heavy wood carved furniture they had in there and likely has nothing to do with humidity or the HVAC system.
I've read a lot on these WHH's and the general consensus is that the risks of issues outweighs the benefits from a whole house humidifier. Any thoughts on this? If I did try to use it I would just keep it at its lowest possible setting. Should I fire this thing up??


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## Jeff Handy (Dec 4, 2019)

Yes, use the humidifier on the furnace.
Change the evaporator pad if it looks too crusty.
Make sure it is not leaking all over the place. 

You have to adjust the humidity level as temps rise and fall.

Your free-standing humidifier is going to be more unsanitary than a furnace mount that constantly is flushing itself out.

And hot air ducting will not be growing mold.

Exposed wood subfloor is very likely also fine.
Check the wood where basement concrete walls support main floor, for excess moisture. 
Make sure there is a return vent open in basement, for circulation. 

The floor might squeak less with the humidifier running. 
You can also add screws into the flooring from below. 
Or from above, if you have carpet. 
Look up Squeakender on Google.  

There is usually a little chart on the humidistat that indicates typical settings to follow, to correspond with high or low outside temps.
To avoid excess condensation at cold spots. 

Put a cool mist humidifier by your bedside, use it at night, works wonders for dry sinuses.
Don’t run too high, watch the window bottoms for condensation.
I have one, I add a tiny drop or two of bleach every other refill.
No mold, algae, or yuck grows in it, never needs cleaning except to put away in spring.

Leave the bathroom door half open during your shower. 
Free humidity!


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## Billbill84 (Dec 5, 2019)

Jeff Handy said:


> Yes, use the humidifier on the furnace.
> Change the evaporator pad if it looks too crusty.
> Make sure it is not leaking all over the place.
> 
> ...


That all sounds great but my big issue is that my basement is fully finished so I cannot inspect anything on the walls, wood framing. Can't see any rim area either except a very small area which looks fine I think. Should note that on my exterior walls on the main floor the very edge of carpet right at the baseboards and the baseboards themselves area very cold in the winter. Not sure if that's normal or not but from what I said about not being able to inspect 99.9% of the stuff from the basement it's a big concern for me. 
Also you're saying mold can't grow in the ducts? Not even on any dust or dirt that may be in there ?


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## Jeff Handy (Dec 5, 2019)

You are too obsessive about many little things that don’t really matter in the bigger picture.

So I am out, you seem too fussy and fearful to be doing anything DIY.

Just hire pros and get on with your life.


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## Billbill84 (Dec 5, 2019)

Jeff Handy said:


> You are too obsessive about many little things that don’t really matter in the bigger picture.
> 
> So I am out, you seem too fussy and fearful to be doing anything DIY.
> 
> Just hire pros and get on with your life.


Sorry I wasn't trying to be rude or anything the problem is that there's so much BAD info out in the web and page after page is nothing but crap about mold. I've been a DIY guy my whole life and when u buy a house with so many "new" options then discovere morons were improper DIY'ers, must proceed with caution when I start tinkering with this stuff. Bought a lemon so I'm stuck with it.


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## Jeff Handy (Dec 5, 2019)

Mold and germ problems are extremely over-hyped.

Children raised in super-clean houses wind up less healthy than those exposed to dirty environments, the immune system needs to be challenged.

We got along for thousands of years without mold remediation services, duct cleaning, or any of that.

We evolved to be fine sleeping on the ground in moldy leaves.
Eating raw food, sometimes fairly old and fuzzy, maybe occasionally cooked, then wearing stinky old animal skins that were covered in natural molds and bacteria.

Your house is very likely less a lemon than you think, so get over it.


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## Diehard (Dec 5, 2019)

I agree you never know what to believe of information found on the web. In doing a fair amount of research, I've come across this reference, in many places, to lower the humidity settings in conjunction with the outdoor temps.

It is not just the RH but a consideration of the dew point. Condensation on the inside of your windows is an indication that the humidity may be too high

As a general rule, here’s how it should be: the lower the outdoor temperature, the lower the indoor humidity. 

If outside temperature is 20 to 40 degrees, humidity indoors should not be more than 40 percent.
If outside temperature is 10 to 20 degrees, humidity indoors should not be more than 35 percent.
If outside temperature is 0 to 10 degrees, humidity indoors should not be more than 30 percent.
If outside temperature is 10-below to 0, humidity indoors should not be more than 25 percent.
If outside temperature is 20-below to 10-below, humidity indoors should not be more than 20 percent.
If outdoor temperature is lower than 20-below, inside humidity should not be more than 15 percent.
A second hygrometer maybe worthwhile since they do vary.


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## Billbill84 (Dec 5, 2019)

Jeff Handy said:


> Mold and germ problems are extremely over-hyped.
> 
> Children raised in super-clean houses wind up less healthy than those exposed to dirty environments, the immune system needs to be challenged.
> 
> ...


No, you're absolutely 100% correct and I thank you for sharing your knowledge and helping out. You're very knowledgeable. Everything is over-hyped these days. Honestly was just a tad paranoid after dropping 300k on a house that had many issues and the more I dig the more I find. Like piles of old raccoon crap in the attic when I went to check the flex ducts for leaks because upstairs was so cold. Seriously how does an "inspector" miss that! Turns out the insulation is a mess up there cuz of the damn coon they had. There's not a single window or door that has ANY flashing around it. Who doesn't insulate ducts if you're gonna bury them behind a drywalled basement ceiling? Who finishes a basement without insulating the rim joist? Lol.


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## Jeff Handy (Dec 5, 2019)

I have never seen basement furnace ducts insulated.
Exposed, or behind drywall or drop ceilings. 
Maybe it is common elsewhere, but near Chicago, no way.
Just bare metal.

Yes, the joist spaces all around the top of the concrete basement walls should be insulated. 

Cut the ceiling open, insulate, and then get off your drama high horse, please.


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## Billbill84 (Dec 5, 2019)

Diehard said:


> I agree you never know what to believe of information found on the web. In doing a fair amount of research, I've come across this reference, in many places, to lower the humidity settings in conjunction with the outdoor temps.
> 
> It is not just the RH but a consideration of the dew point. Condensation on the inside of your windows is an indication that the humidity may be too high
> 
> ...


Thank you for all the great info. I took a screen shot of your editorial here to use as a reference. I think I'll just run it the first few days at a low/medium setting to "test the waters". 
Does the humidifier only run when the furnace kicks on? It's an older unit so I'm not too sure on how it works but my basic knowledge tells me that the celinoid thing opens when the furnace tells it "hey I'm running so u need to open".


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## Billbill84 (Dec 6, 2019)

Jeff Handy said:


> I have never seen basement furnace ducts insulated.
> Exposed, or behind drywall.
> Maybe it is common elsewhere, but near Chicago, no way.
> Just bare metal.


Yeah I'm in crown point Indiana (NWI) right by Chicago, so that's very reassuring to know! When I saw wet metal near the air handler all I heard was "your ducts need insulation". Then learned on the forum that "bottom line is condensation is only there if there's a moisture source in the air" put the dehumidifier in that room and boom, condensation was gone! Ended up finding out next summer that my A-coil was spewing refrigerant as it was leaking so I'm blaming that for having something to do with that issue lol


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## Jeff Handy (Dec 6, 2019)

Post a pic of the humidifier. Showing the model number. 

Most, like Aprilaire, only run when the furnace blower runs. 

That humidity setting info should already be printed on your humidifier humidistat control.


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## Billbill84 (Dec 6, 2019)

Jeff Handy said:


> Post a pic of the humidifier. Showing the model number.
> 
> Most, like Aprilaire, only run when the furnace blower runs.
> 
> That humidity setting info should already be printed on your humidifier humidistat control.


Here it is. There's also a block looking thing that's mounted to the side wall of the furnace not sure what that thing is


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## Jeff Handy (Dec 6, 2019)

The block thing is a transformer. 
It takes switched a/c power from the furnace blower control, converts to low voltage to control the humidistat. 
The humidistat has the twist knob to control humidity output.


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## Billbill84 (Dec 6, 2019)

Jeff Handy said:


> The block thing is a transformer.
> It takes switched a/c power from the furnace blower control, converts to low voltage to control the humidistat.
> The humidistat has the twist knob to control humidity output.


Ok looking at it now that makes sense I just didn't understand why a transformer had any business there but now I know.


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## Fireguy5674 (Dec 6, 2019)

The one I put on my mother-in-laws furnace last year has a temperature probe on it that senses outside air temp and adjusts inside RH to the requirement for that temp.  It can kick the furnace blower on and blow air through the system to add humidity if operating only when the furnace runs will not satisfy the humidistat.  You can adjust the humidistat to accommodate your comfort level.  The humidistat has a probe in the duct that monitors the RH of the air moving through the ducts.  As long as everything is working correctly and you are seeing no condensation on windows etc. everything should be fine.  As someone suggested, buy a separate humidistat and set it on the end table in your living area as a backup.  You will probably be causing more damage to your family and your house without a humidifier than with one.  Not to mention that moist air feels warmer so you will probably set your thermostat slightly lower, save money and be more comfortable.


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## DFBonnett (Dec 6, 2019)

OP,
Don't trust the humidistat on the furnace to be accurate. Get a freestanding hygrometer and place it in your living space, then adjust the humidistat on the furnace accordingly. BTDT.


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## Jeff Handy (Dec 6, 2019)

Looks like there is also another big control knob on your humidifier. 
I think it is a damper control, to divert more or less air through the humidifier.


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## Billbill84 (Dec 6, 2019)

Fireguy5674 said:


> The one I put on my mother-in-laws furnace last year has a temperature probe on it that senses outside air temp and adjusts inside RH to the requirement for that temp.  It can kick the furnace blower on and blow air through the system to add humidity if operating only when the furnace runs will not satisfy the humidistat.  You can adjust the humidistat to accommodate your comfort level.  The humidistat has a probe in the duct that monitors the RH of the air moving through the ducts.  As long as everything is working correctly and you are seeing no condensation on windows etc. everything should be fine.  As someone suggested, buy a separate humidistat and set it on the end table in your living area as a backup.  You will probably be causing more damage to your family and your house without a humidifier than with one.  Not to mention that moist air feels warmer so you will probably set your thermostat slightly lower, save money and be more comfortable.


Thanks. A second backup hygrometer is on order!


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## Billbill84 (Dec 6, 2019)

Jeff Handy said:


> Looks like there is also another big control knob on your humidifier.
> I think it is a damper control, to divert more or less air through the humidifier.


Yes there's a damper control so I'm trying to figure out how this thing works with that control. Looks like the return air hits the humidifier on its way in but some return air is then diverted through that damper control and into the supply side plenum above the furnace. What's the purpose of the damper control when I thought the humidistat tells the celinoid valve how much to open based on the humidistat % setting, then there's that damper. I guess just a balancing act


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## Billbill84 (Dec 6, 2019)

Here's how it's set up


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## 68bucks (Dec 7, 2019)

So here is a problem I'm having with this issue right now. We bought this place 4 years ago. I inspected everything and the place was solid, no serious issues. We installed hardwood floors and my wife has serious sinus problems so I installed a whole house humidifier. We keep the RH about 40%. Last winter after a long really cold spell I noticed dripping from an odd place, like the roof was leaking. I crawl in the attic and it's raining in there, sopping wet mold everywhere. I panic but discover the 2 bathroom vents just vent to the attic space. Well I correct that with proper though the roof vents and think I'm good, it'll dry in the summer heat. Well I crawled up there 2 days ago now that's cold again to make sure it's still dry and to evaluate the mold and decide if I need to look at remediation. Well it's better but I still have too much moisture. I can see a drop of water on the ends of many nails. So the only thing I can think that is different since we moved in is the humidifier. So I'm back to the drawing board to figure out what to do.


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## Billbill84 (Dec 7, 2019)

68bucks said:


> So here is a problem I'm having with this issue right now. We bought this place 4 years ago. I inspected everything and the place was solid, no serious issues. We installed hardwood floors and my wife has serious sinus problems so I installed a whole house humidifier. We keep the RH about 40%. Last winter after a long really cold spell I noticed dripping from an odd place, like the roof was leaking. I crawl in the attic and it's raining in there, sopping wet mold everywhere. I panic but discover the 2 bathroom vents just vent to the attic space. Well I correct that with proper though the roof vents and think I'm good, it'll dry in the summer heat. Well I crawled up there 2 days ago now that's cold again to make sure it's still dry and to evaluate the mold and decide if I need to look at remediation. Well it's better but I still have too much moisture. I can see a drop of water on the ends of many nails. So the only thing I can think that is different since we moved in is the humidifier. So I'm back to the drawing board to figure out what to do.


You have attic rain. 40%RH during a cold spell is way too high I think


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## 68bucks (Dec 7, 2019)

When I research proper indoor humidity for health and comfort it almost always suggest 3 5-50%.


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## Billbill84 (Dec 7, 2019)

68bucks said:


> When I research proper indoor humidity for health and comfort it almost always suggest 3 5-50%.


Yes depending on the outside temperature!


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## Jeff Handy (Dec 7, 2019)

You should be able to find the manual online, to explain the operation.

You have to lower the humidity setting as the temperature goes down, or you will get the condensation problems you have now.

You can also install a roof ventilator fan, which can work year round.
It pulls out hot air in summer, and in winter it comes on when the air gets too clammy and pulls that out.

You also might need to improve the air circulation and intake-exhaust venting openings. 
Soffit vents can also get blocked by insulation. 

As far as the mold, you can use Concrobium mold killer from Home Depot or elsewhere.
You can rent a Concrobium fogger, which fogs all the wood surfaces.
The Concrobium kills the mold and encapsulates it as it dries.
It needs to be done when the wood is dry, like in warmer weather.


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## 68bucks (Dec 7, 2019)

I saw your table of indoor RH vs outdoor temp. I found that same thing online in 1 place. So what does the outside temperature have to do with the indoor RH? The indoor RH is controlled to keep wood from drying out, to keep the house more comfortable, for health reasons, such as preventing sore throats, dry sinuses, etc, reduced static charges, and many other things. That's the whole point of humidifing a house. The numbers you posted would be about what the RH would be at those Temps is you didn't add moisture to the air. So I don't understand the correlation of the outdoor temp and indoor RH, can you explain the logic to me?


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## Jeff Handy (Dec 7, 2019)

Because most houses have some problems with cold spots, air leaks, voids in insulation, drafty windows, or poor ventilation in the attic or crawlspace, the humidifier can add too much moisture than the house can tolerate, as the temperature goes down. 

So even though it seems counter-intuitive, you usually have to back off the humidifier output as the outside temps drop. 

Even though you would actually want that extra moisture, you have to make a sacrifice and cut it back, or else you will usually get a condensation problem, which gets worse as the outside cold affects surfaces in the house or attic.


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## 68bucks (Dec 7, 2019)

Oh I undeserved that but if everything is properly designed and functioning then there is no issue. If you think 15% RH in your house is ever good I whole heartedly disagree.


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## Fireguy5674 (Dec 8, 2019)

As I wrote in an earlier post here, the humidifier that I installed last winter came with an outside temp probe that is tied into the controller and reduces RH in the house as the temp drops outside.  Since I  assume the engineers who designed the thing probably are a lot smarter than I am about how the RH in the home should work, I would say that table is pretty close to correct.  I don't have the table that was enclosed with the humidifier.


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## Diehard (Dec 8, 2019)

"_*2 bathroom vents just vent to the attic space.*_" 
That's a NO-NO!
Bathroom vents should be ducted to the exterior.


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## Diehard (Dec 8, 2019)

68bucks said:


> Oh I undeserved that but if everything is properly designed and functioning then there is no issue. If you think 15% RH in your house is ever good I whole heartedly disagree.


That's only when the outdoor temperature is *lower than 20-below.*
I believe it has to do with the dew point, which, of course is the actual point where you start getting damaging condensation.
If it is too dry for you, you can increase it a bit but should then try to insulate your house better.


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