Ball Python off feed

[Bogertophis]

... Do you know what watt bulb I should buy instead?

That's something only you can test & find out, as the cooler your room is, the more heat loss you'll have from his home. You should be controlling any & all heating devices with a thermostat for safety also. If you're only using an overhead heat source, you might do well to add UTH under a third of the enclosure (especially in the cooler months of the year), but again, it must be controlled.