I replaced the fill valve on a toilet and the connection stem on the replacement sticks out much farther than the original. The toilet was installed 12 years ago using a solid supply line, so I need to replace that to reconnect it. The nut holding the supply line to the shutoff valve won't budge. There's probably some minerals in there, but I suspect the original installer used some serious torque to ensure it wouldn't leak.
The metal shutoff valve connects to a PVC feed pipe. I can't figure out a way to secure the valve and leverage against that to loosen the nut. I'm worried about damaging the PVC connection to the valve.
Any suggestions for how to solidly grab the valve in a way that I can put torque on the nut in relation to the valve, without stressing the valve connection to the PVC pipe?
I considered heating the nut with a torch to expand it, but I'm worried about plastic internal parts. I also couldn't figure out a way to get Liquid Wrench into the threads, so I assume brute force is the solution. If there's a better way, ideas are welcome.