Need advice on how to replace a Watts Series 8 Model 8A non-removable vacuum breaker.
There is a repair kit available for that part. Since it is designed to be non- removable, I would assume you can repair it in place.
Your other option, depending on what's wrong with the first one, could be to just screw another vacuum breaker onto the existing one without removing it.
If all else fails, I think you're going to be cutting it off with an angle grinder, dremel, or similar.
You do know the meaning of non-removable, right? That being said, you'll need to replace the spigot. Those fittings have a brake-away threading system that allows you to tighten them for installation but breaks away the sleeve from the threads if you try to turn it counterclockwise. Something like the safety caps on pill bottles. Now, I have removed them with a Dremel drill with a cutoff wheel and carefully cut the breaker off of the spigot but it was a slow process so I wouldn't damage the threads on the spigot. the next time I came across one that had to be removed, i just replaced the spigot and added a new breaker.
This vacuum breaker is titled "non-removable" for good reason.
The unit is secured by a set screw that is snapped off through tightening. If you need to remove it the only way I see to do it is to completely drill out the set screw with a metal drill bit. I believe the only other option is to replace the entire spigot.
I would try drilling it first.