Honeywell UV Light Treatment System Replacement Bulb

The ultraviolet light bulb in my Honeywell UV100A 1059 germicidal surface treatment system in my central air conditioner burned out after two summers. Honeywell’s replacement light bulb is part number is the UC36W1006/U which is actually a Philips TUV PL-L light bulb made in Poland. Finding a Philips TUV PL-L replacement bulb was a bit of challenge due to several after-market brands sold under a similar name and concerns the Honeywell bulb has a keyed base. I ultimately purchased a genuine Philips 265850 36-watt PL-L TUV light bulb that fit perfectly and cost 50% less compared to the Honeywell branded bulb.

Honeywell UV Light Treatment System Replacement Bulb

The Honeywell UV100A 1059 ultraviolet air treatment kit (available at Amazon.com) includes a Philips 265850 36-watt light bulb:

Honeywell Ultraviolet Surface Treatment System UV100A1059

Philips 265850 TUV PL-L Ultraviolet Germicidal Lamp

The Philips 265850 TUV PL-L light bulb has a rated life of 9,000 hours. I run the central air conditioner about 5-1/2 months per year which means the UV light is On 24×7 during these months or about 4,000 hours/year. After slightly more than two cooling seasons the original light bulb burned out this Spring close to the 9,000 hour mark.

This is the burned out Honeywell/Philips UV light bulb and the new Philips bulb installed in the Honeywell UV100A 1059 base unit. The new light bulb fit perfectly:

Honeywell UV100A1059 UV Light with Philips TUV PL-L Replacement Lamp

The burned-out bulb is on the left and the new Philips bulb & box is on the right in the following photo. Remember – do not touch the light bulb with your bare hands because oil from your finger prints will create a hot-spot on the bulb. Always handle the bulb with a dry clean cloth.

Philips 265850 36 watt TUV PL-L Ultraviolet Germicidal Lamp – Honeywell Original and Replacement

The product label on the new bulb identifies it as a Philips 265850 36 watt TUV PL-L germicidal lamp with a 4-pin base. The 4-pin base is a 2G11 style.

Philips 265850 36 watt TUV PL-L Ultraviolet Germicidal Lamp Replacement for Honeywell UVA100A1059

The new Philips UV light bulb works fine in the Honeywell UV100A 1059 installed in my air handler above the evaporator coils:

Honeywell UV100A1059 UV Light in Air Handler Plenum

Keyed versus Non-Keyed Philips TUV PL-L Light Bulbs

The original/burned-out light bulb and the new replacement bulb are identical on the label side:

Philips 265850 36 watt TUV PL-L Ultraviolet Lamp – Label Side

The other side of the original Honeywell UV100A 1059 lamp has two key slots milled in the base whereas the new Philips bulb does not:

Philips 265850 36 watt TUV PL-L Ultraviolet Lamp – Opposite Side

The key slots were milled (machine cut) after the bulb was manufactured as evidenced by the plastic burrs. The reason for keying the bulb is probably to discourage consumers from buying lower quality bulbs not made by Philips although the impact on the smart consumer is a proprietary lock-in forcing you to buy the more expensive Honeywell branded UC36W1006/U bulbs.

My Honeywell UV100A 1059 lamp socket is not keyed so it doesn’t matter how the bulb is inserted in the socket. It does have two raised friction tabs molded to grip the bulb base so it doesn’t fall out:

Honeywell UV100A1059 UV Light – Base Unit Bulb Socket

Side view of the UV100A base unit:

Honeywell UV100A1059 UV Light – Base Unit

I removed the two #10 tamper-proof torx screws to inspect the base unit socket wiring. The black wires connect to the inner pins and the red wires to the outer pins of the light bulb. This confirms the light bulb electrical connections are identical when the bulb inserted in any orientation. Had my socket been keyed it would serve no purpose from an electrical point of view:

Honeywell UV100A1059 UV Light Socket Wiring

If the lamp socket in your Honeywell base unit is keyed, one Amazon.com reviewer cut the raised plastic keys with knife so the non-keyed genuine Philips TUV PL-L bulb would fit. I’m not recommending that you do this and it will void the 5 year Honeywell warranty.

Take care,

Bob Jackson

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