A Simple DIY Upgrade: Using a Baomain Timer Relay for Efficient Humidifier Control

Published on January 14, 2026 by Claudio Cabete

Most homeowners with a bypass or flow-through humidifier don't realize how much water and furnace heat they're wasting. These systems are typically wired so that whenever the furnace is running and the humidistat is calling, cold water flows continuously across the pad.

That means:

  • The pad stays cold
  • Evaporation efficiency drops
  • Water waste skyrockets
  • Mold risk increases

In earlier posts, we explored why intermittent water flow (e.g., 10 seconds ON, 120 seconds OFF) dramatically improves efficiency and reduces waste. If you have a custom controller — like the Pico-W-based Homatica HVAC optimizer — implementing this logic is trivial.

But what if you don't have a custom controller?

What if you want a simple, inexpensive, off-the-shelf solution?

Good news: you can get 80% of the benefits with a $12 Baomain programmable timer relay.

Why the Baomain Timer Is a Great Fit

The Baomain CN101A (and similar models) offer a rare combination:

  • Accepts 24 VAC input
  • Has an internal relay rated for HVAC loads
  • Supports custom ON/OFF cycles
  • Costs around $10–$15
  • Fits easily inside or near the furnace cabinet
  • Requires no microcontroller or programming skills

This makes it an ideal DIY upgrade for homeowners who want intermittent humidifier control without building electronics.

How It Works

The Baomain timer sits between the humidistat and the humidifier solenoid valve. Instead of letting the solenoid run continuously, the timer pulses it:

  • 10 seconds ON
  • 120 seconds OFF
  • Repeating automatically
  • Only when the humidistat is calling for humidity

This keeps the pad wet, lets it warm up, and maximizes evaporation — all while using a fraction of the water.

Wiring Overview

Below are two diagrams: 1. A conceptual block diagram showing the logic flow 2. A practical ASCII wiring diagram showing how to wire the Baomain timer into a typical 24VAC humidifier circuit

Conceptual Diagram

+------------------+ +------------------+ +------------------+ | Furnace HUM | ----> | Humidistat | ----> | Baomain Timer | | (24VAC source) | | (calls for RH) | | (pulses water) | +------------------+ +------------------+ +------------------+ | v +------------------+ | Solenoid Valve | +------------------+

ASCII Wiring Diagram (Typical 24VAC Humidifier)

           (24VAC from furnace HUM or transformer)
                           |
                           v
                    +--------------+
                    | Humidistat   |
                    +--------------+
                           |
                           v
                    +----------------+
                    | Baomain Timer  |
                    |   (Relay)      |
                    +----------------+
                           |
                           v
                 +----------------------+
                 | Humidifier Solenoid  |
                 +----------------------+
                           |
                           v
                       Return (C)

More detailed version with terminals labeled:

Furnace HUM (24VAC Hot) -----> [Humidistat IN] [Humidistat OUT] -----> [Timer COM]

Timer NO (Normally Open) -----> [Solenoid Valve +]

Solenoid Valve - --------------> Furnace C (24VAC Common)

Timer power: Timer L <------------------ Furnace HUM (24VAC Hot) Timer N <------------------ Furnace C (24VAC Common)

Recommended Timer Settings

A great starting point:

  • ON time: 10 seconds
  • OFF time: 120 seconds
  • Mode: Repeating cycle
  • Active only when humidistat is calling

Why Not the Asymmetric Timer?

Baomain also sells an asymmetric ON/OFF cycle timer, but:

  • The form factor is bulkier
  • The wiring is less intuitive
  • It's harder to mount cleanly
  • It's designed for industrial panels, not HVAC cabinets

The CN101A-style timer is simpler, cleaner, and easier to integrate.

Final Thoughts

If you want a smarter, more efficient humidifier without building a custom controller, the Baomain timer relay is a fantastic DIY upgrade.

You get:

  • Better evaporation
  • Lower water usage
  • Reduced furnace heat loss
  • Lower mold risk
  • A more modern, controlled humidifier
  • All for about $12

It's one of the highest-impact, lowest-complexity improvements you can make to a flow-through humidifier — and a perfect stepping stone toward a full Homatica-style smart HVAC system.

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