York is a Johnson Controls HVAC brand. Many York whole-house humidifiers are built around the same water panel design Aprilaire uses, so the replacement for your York unit is typically an Aprilaire #10 or #35 equivalent, the same part used across several HVAC brands.
We carry Tier1 comparable water panels in both sizes, sold in 2-packs. The #10 is the panel used in Aprilaire's Models 110, 220, 500, 550, and 558, while the #35 fits Models 600, 700, and 760. Check the part number on your current panel or the label inside your humidifier's cover to confirm which size you need.
Replace the panel once per heating season, or sooner if it turns stiff, cracked, or heavily scaled.
Not sure which panel fits your York humidifier? Call 1-800-277-3458.