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Normally evaporative humidifiers don't do that to ducts - only a spray mist type could. Unless you have a water quality issue.

Low rh in winter can be caused by too much air leakage.

Normal level range is 25 to 40% in winter depending on weather.
 

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i don't know maybe the extra sodium from the softener is doing it?
 

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I'd get a different humidifier before the duct damage gets any worse. If you can't easily install an air bypass type, then a power model can work. Both of those use a pad that evaporates the water rather than spraying it in as a mist. The power type takes air from the supply duct, runs it through the pad and blows it back into the same duct. It could use the same hole you have now.
 

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Discussion Starter #8
I'd get a different humidifier before the duct damage gets any worse. If you can't easily install an air bypass type, then a power model can work. Both of those use a pad that evaporates the water rather than spraying it in as a mist. The power type takes air from the supply duct, runs it through the pad and blows it back into the same duct. It could use the same hole you have now.
I do have a flow through type and not a spray/mist kind. Im surprised to see all that sediment and rust.
 

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Re-reading, I see you have it attached to the return air duct. If that duct gets cold, it could be dew pointing the discharge and wetting the duct. Moving that to the supply duct would stop that... most are installed on the supply duct since they work much better there. Can you do that?
 

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Re-reading, I see you have it attached to the return air duct. If that duct gets cold, it could be dew pointing the discharge and wetting the duct. Moving that to the supply duct would stop that... most are installed on the supply duct since they work much better there. Can you do that?
Looks like he has a bypass humidifier. If so, then it doesn't matter if its installed on the supply or return duct.

Looks like the system is short on return, and pulling the moisture off the pad and not just vapor.
 

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The velocity of the air going across the pad may be blowing water off it and hitting the duct.

On mine I don't leave the damper to it wide open/just halfway open. You don't need a full 5 to 6" pipe worth of airflow bypassing your furnace and going thru the humidifier.

Just enough to pick up the moisture from the pad as it evaporates.

If you have a damper on the bypass pipe as you should then try close it halfway next winter to slow down the air.

If your return air ducts are too small and there is excess suction then it may suck the water off.

I would try closing the damper halfway first. I looks like salt deposits and won't likely hurt anything, just looks ugly.
 

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The base mounting housing doesn't look like it could be a bypass type unit.

What is the make and model of this humidifier?
Did you have it installed or was it there when you bought the house?
To your knowledge, Was there ever a different type installed?

If there ever was an atomizing spray type installed, we may be trying to fix a problem that no longer exists.
 

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Take the bottom pic and turn it 1/4 turn clockwise and you can see the drain hose.
 

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A static pressure test can determine if it's short of return, supply or both. Being really short of return may hide undersized supply.

How much humidification you need depends on the climate and how leaky the house is. It may be necessary to leave the damper completely open to get enough humidification.

Granted if the return is undersized, closing the damper a bit may drop airflow to normal level.
 

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Discussion Starter #16
What is the make and model of this humidifier?
Did you have it installed or was it there when you bought the house?
To your knowledge, Was there ever a different type installed?

If there ever was an atomizing spray type installed, we may be trying to fix a problem that no longer exists.
I removed the drum humidifier the original owners had and replace it with an aspilaire flow through unit. I'm actually not sure whether the rust/sediment only started to occur after I install my unit, or if it was happening before. I do see a lot of sediment dust when i change my furnace filters so that makes me believe the problem is happening now.

The velocity of the air going across the pad may be blowing water off it and hitting the duct.

On mine I don't leave the damper to it wide open/just halfway open. You don't need a full 5 to 6" pipe worth of airflow bypassing your furnace and going thru the humidifier.

Just enough to pick up the moisture from the pad as it evaporates.

If you have a damper on the bypass pipe as you should then try close it halfway next winter to slow down the air.

If your return air ducts are too small and there is excess suction then it may suck the water off.

I would try closing the damper halfway first. I looks like salt deposits and won't likely hurt anything, just looks ugly.
Good suggestion about the damper.


Would you replace the rusted section of the ductwork?
 

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Unless it has holes in it I would leave it alone.

It should be galvanized metal and not likely going to rust through.
 
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