i can't say, and don't really know if there's a 100% correct answer for this.....
we did the same for a bit because our temps were well below 20 degrees F. And the wind chill made it much worse.
Ours is still on currently 24/7 becuase it's keeping the water from freezing for the most part... so until we get one, we may keep it on. I don't want to keep it on though because i've read on here that chickens are pretty hardy..... We have some insulation so it does get chilly but no where near what it is outside obviously. I don't think it's good for them for long periods of time.... messes up their sleep and knocks them for a loop i believe.... not to mention, when it gets warmer... we don't want 'fried chicken'
I think you can keep it on if the wind is bad or if the temps drop etc.... we have ours on a timer usually though. I've read they like to use each other for heat as well. And if you use a deep litter method in the coop, that helps keep some of the warmth in. (hope all that's correct - that's from reading posts on here)
~ do you have pictures of a red light in a clay pot? I don't think i understand just what you mean and/or the purpose or it....
We have ours hanging from the ceiling......