# Does a whole house humidifier promote mold growth

**URL:** <https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519>\
**Category:** Factual Questions\
**Created:** [October 28, 2009, 11:17pm UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519 "2009-10-28T23:17:49Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\
**Post date:** [October 28, 2009, 11:17pm UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519/1 "2009-10-28T23:17:49Z")

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Seems like it would have to keep the inside of your duct work damp which would promote mold. Then you’re breathing the mold.

What am I missing?

-rainy

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**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\
**Post date:** [October 28, 2009, 11:39pm UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519/2 "2009-10-28T23:39:01Z")

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if you keep it below 60% you will be OK.

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**Author:** ![rainy](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@rainy](https://boards.straightdope.com/u/rainy)\
**Post date:** [October 29, 2009, 12:26am UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519/3 "2009-10-29T00:26:43Z")

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> [@johnpost](#):
>
> if you keep it below 60% you will be OK.

Is this as easy as a setting on the system itself?

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**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\
**Post date:** [October 29, 2009, 12:36am UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519/4 "2009-10-29T00:36:53Z")

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> [@rainy](#):
>
> Is this as easy as a setting on the system itself?

human comfort level is 30% to 60%, you need to find what you like you humdistat set at. less than 30% the air will be dry and cause static electricity and dry nose (bloody noses) and dry lungs. over 60% you will get condensation on cold windows allowing mold and rot there.

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**Author:** ![EmAnJ](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@EmAnJ](https://boards.straightdope.com/u/EmAnJ)\
**Post date:** [October 29, 2009, 1:09am UTC](https://boards.straightdope.com/t/does-a-whole-house-humidifier-promote-mold-growth/515519/5 "2009-10-29T01:09:55Z")

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> [@rainy](#):
>
> Is this as easy as a setting on the system itself?

I have a dial right beside the thermostat. In my old house, the humidifier was for the hardwood (it’s very dry here and hardwood needs moisture), and the adjustment was on the computerized thermostat.