How to control humidity of a very small space using a RasPi?

Question

What techniques (with pros and cons) can be used to monitor and control humidity - create small amount of steam when necessary?

It seems pretty easy to monitor temperature and humidity but I never seen someone actually trying to control humidity using a RasPi, e.g. Heat element and water.

My interest is for very small area or more precisely, Cigars humidor.

Answer 1

Disclosure: I've never attempted anything like this, but I try to conceive what an answer may look like.

As you have noticed, there are lots of projects to monitor humidity, so Im not going to get into that. Once you know you have reached a critical point where humidity is lower than preferred to create steam you could use something like this setup.

• 2 X WeMo power outlets - using APIs found in GitHub, you could turn them on/off
• 1 X water pump
• 1 X canister, the size that you'd like. The larger, the less you will have to tend to it.
• 1 X heating element - check camping supplies, the cheaper the better

I would have the logic do the following:

1. When we need more humidity, turn on heating element and
2. Wait 2 mins (variable, depending on how quickly it can heat up) - this may be optional
3. Turn on water pump - depending on its flow rate, possibly for just 1-2 seconds
4. Wait 2-3 mins and then measure humidity again

This may serve as inspiration on how to setup a water pump, and possibly which to get: http://www.instructables.com/id/Small-DIY-Aquaponics-System/?ALLSTEPS

To lower the humidity you could try just turning on the heating element for a few mins and see if it lowers it, I suspect it may.