Like many people my furnace runs much the winter, so I need a humidifer to keep the air from getting too dry. When the furnace runs a lot, the humidifier needs to be re-fill every day, sometimes twice a day.
My humidfier is located in the utility room and there's a faucet nearby - so all that was needed was a way to automatically refill the humidifer from that water source.
With just a few basic components it was surprizingly easy to create a simple auto-fill system.
1) An electric solenoid valve & power supply - commonly used for irrigation systems and readily availabe at a Home Depot or Lowe's.
2) A DIY float and a limit switch, this energizes the solenoid valve to refill the humidifer tank if it's low.
3) Common lamp / appliance timer (the kind you might use to turn the lights on and off while on vacation). With this you can scheudle a few "fill check & re-fill if needed" cycles each day.
4) A few hose and electical connectors.
You should be able to get everything locally except prehaps the limit switch, total cost should be < $50. Say goodbye to manual refilling !!
Another Option - Of course the best solution, allbeit at more cost and complexity, is a whole house humdifier that attaches to a forced air furnace.