LOVATIC Nipples installation

[Hetken1]

Hi, I am building a new heated watering system using the Lovatic Nipples. I would like to install them towards the bottom of the 4" PVC pipe I am using. This would leave less water in the bottom of the unit.
Question: Do these nipples need to be level, or can they be pointed a bit down ?
Ken

 

[EmtheFishLady]

I have no idea, because my husband does all the hard, complicated stuff, I’m just posting to bump your post up and hopefully someone with sense will answer you soon.