I want to replace the washer inside a boiler drain valve because it's leaking. However, I am unable to unscrew a nut that holds the valve stem in place. I have tried a variety of hand tools, so far it hasn't budge. Do you think an impact wrench would help in this case, will it damage the pipes and/or other connections of the system? In general, is it good practice to use impact wrench on plumbing work?
The red arrows points at the "nut" (not sure what to call it) I want to loosen. The valve is a hammond 710.
Thanks in advance.