Overview

Honeywell HE280C2010/U Higher Capacity Whole House Bypass Humidifier

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Parts

Humidifier Pad - HC26A

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Fix - No Water Flow

A some point the solenoid failed. I think the original solenoid is garbage so I will replace with something a bit more robust. 

Controller Images

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Schematic

Here is the schematic that I put together based on some testing.

Based on this schematic, I'm thinking that the transistor Q1 is bad. You would think that the GND pin on the 555 would go to ground via a pullup and that would be that.

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• D2 is a zener diode which acts as a voltage regulator for the 555 chip.

555 Timer Reference Diagram

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Fixing the Solenoid

Since the solenoid was no longer activating, it seemed like a replacing it was in order. The replacement solenoid that I purchased was rated 24 VDC but didn't activate when connected. Perhaps the transistor Q1 does support the amount of current required by the new solenoid. 

I opted to bypass the 555 timer circuitry by connecting pin 4 of the internal connector (under cap) to ground. The 555 timer is not required. 

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New Parts

Finish Product

Here is a picture of the finished fix. Should be more maintainable now that these changes have been made. The new solenoid valve will allow a lot of water to pass so I have ball valve (not shown) limiting the flow to a trickle.

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Future Updates

• Replace solenoid output connector with barbed connector

References