I purchased the Honeywell UV100A-1059 UVC UV Surface Treatment Coil light. Upon further investigation prior to installation I found that the bulb is likely too long to fit within the supply duct above the A coil. The only side of the duct I could put it in that would have the potential distance needed is at a slope and the bulb itself would be sloping into and possibly contact the A coil which I know we don't want to do. I see there is also a return side version that has a shorter bulb (Honeywell UV100E-1043 SmartLamp UV Air Treatment System, Single Lamp Return Air). This model is more expensive (likely due to the sensor that detects when there is airflow to turn the lamp on and off). What I am wondering is, is it possible to use a replacement bulb for the UV100E-1043 in the UV100A-1059 since it is shorter? The larger bulb is 42 watts and the smaller, 18 watts but I don't know what impact the unit itself has on this or if like a traditional light fixture, you can use a lower wattage bulb. I have another UV100A-1059 in the second HVAC unit in the house so having a spare bulb that doesn't fit the other duct will get used at some point. If I can't swap the bulbs, is there any danger to using the return side unit on the supply side? I'd rather not spend more just for the sensor that detects the airflow as I'm fine with the bulb always being on keeping the coil mold / bacteria fee (hopefully).

Thanks for your help