Hey guys. I have two brand new WH that I need to connect. My house has passive hot water return circuits that were plumbed into the drain valves of the previous WH. The problem is the new WH come with plastic drain valves that do not want to unscrew with a wrench. Here is a pic: The plastic is kind of soft and it just seems to deform when you push on the wrench. I'm kind of nervous about just cranking on it, they're brand new heaters and they weren't that cheap. Here is how the old WH were connected: A second question is on the return, this section: has to go, for some reason these pieces were joined with silver solder. At first I thought that thing after the cut off valve was check valve but the people at the plumbing store have told me that no, it's a filter. The question I have is should I install a check valve? Or is it not necessary. The plumbing in this house was rather elaborately installed and they didn't skimp on valves so maybe its not necessary?????? Although to my uneducated mind, it would seem like you wouldn't want it to back flow but maybe that's not an issue?

It's give me a code 8 flashes pause 4 flashes, it's telling me that it's a valve fault detected. What does that mean?