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Climate Control Machine

One machine that keeps a bedroom at the temperature and humidity you set, on a schedule, without tanks to empty or refill. Status: concept and design, not built yet.

Why I thought of it

Houston bedrooms swing between two problems. Summer air is muggy, and when the heat runs in winter it gets dry enough that I kept waking up with a parched throat. Fixing that today means a dehumidifier, a humidifier and an AC or heater: three appliances, three apps or remotes, two water tanks to empty or refill, and nothing stopping the humidifier and dehumidifier from fighting each other.

I wanted one box that reads a sensor at pillow height and quietly does whatever the room needs: dry it, moisten it, heat it or cool it, plumbed in so it never needs a bucket.

What already exists

The idea isn't new, which is reassuring: Daikin's Ururu Sarara heat pump heats, cools, dehumidifies and humidifies in one unit, and it pulls the moisture for humidifying from the outdoor air, so there's no tank at all. But it's sold only in Japan and Europe, runs on 240 V, and has no US support or warranty. Nothing sold in the US does all four jobs in one box.

The design

I split it into two phases. Phase 1 is the humidity cabinet: a rolling, counter-height cabinet (24 × 16 × 38 in) with a dehumidifier at the bottom, a wick humidifier on top and a shared 5-gallon tank between them. The dehumidifier pumps its water up into the tank and the humidifier drinks from it; a float valve on a ¼-inch water line tops the tank up only when it runs low, an overflow hose handles the rest, and a UV-C lamp keeps the stored water clean. Phase 2 adds a ductless heat pump for heating and cooling, driven by the same controller.

Open the 3D model and drawings →Turn the model, switch to the exploded view, and see the front, inside, water and airflow drawings with dimensions.

How it decides what to do

A Sensirion SHT45 sensor at pillow height is the reading the controller follows, because the heat pump's own sensor sits up near the ceiling. Around a 55% target, the controller humidifies below 52%, dehumidifies above 58% and rests in between, so the two machines never run at once. The schedule lives on the controller itself (for example 55% from 9 pm to 7 am, 50% during the day), so it keeps running if Wi-Fi drops, and the app warns before you set anything above 60%, where mold and dust mites start to thrive.

Electrical design

An ESP32-S3 runs everything. Mains power only goes to the two appliances and a 12 V supply; everything the microcontroller touches directly is low voltage.

• Fail-safe water. The shutoff valve is normally closed: it only opens while the ESP32 holds Q1 on. A power cut, a crash or a wet leak probe all leave it shut, and the float valve (3) is purely mechanical as a second stop.
• Appliances switch at the outlet. K1 and K2 cut power to the dehumidifier and humidifier rather than reaching inside them, so both keep their own safety features. For a real build I'd use a listed relay outlet box instead of bare relay boards on mains.
• Never both at once. The firmware interlocks K1 and K2, so the two machines can't fight each other even if the schedule asks for it.
• Inductive loads are protected. The flyback diode across the valve coil stops the voltage spike when Q1 switches off from damaging the MOSFET.

Cost

Prices are rough estimates from typical US retail prices, not quotes. The side-blowing dehumidifier is most of Phase 1's cost.

What's next

Pick the exact dehumidifier and humidifier models, finalize the cabinet dimensions around them, then prototype the controller firmware (schedule, humidity band, interlocks and leak shutoff) on the bench with the valve and sensor before any water is connected.