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Starting Member

Posts: 1

Location: USA


Tuesday, June 14th 2005, 2:11pm

Replacing Ball Valve on Backflow Preventer

Need some help or advise. I am in no way a plumber,never really did any plumbing work,but I will try anything once.

I had to replace the outlet ball valve on my Febco 765-1 backflow preventer. I went to Home Depot and bought the new 1" ball valve. To take the old one off I had to screw it all the way to one side to get it off the other,then screw it back the other way to get it completely off. I noticed when taking the old one off that is was soldered on one side of the valve. When I replaced the old on with the new one I get a major leak on one side of the valve depending on where I situate it. I have tried teflon tape on the threads,and joint compound,and nothing seems to help seal it off. Do you think that whoever originally installed the system used solder on one side to stop the leak? If so are there any other alternatives i can try to seal the leak besides solder,because for one I think Im lucky I was able to get the old valve off without cutting it off due to the solder,and for two I dont know how to solder. Can someone help?

Also considered replacing the L-joint thats connected to the pipe going into the ground and the ball valve,but I dont know how the L-joint was installed, its threaded on one end (end connecting to valve) and not threaded on the other end (end going to pipe in ground)


Supreme Member

Posts: 314

Location: USA


Tuesday, June 14th 2005, 7:47pm

Not exactly sure if I am understanding what you are saying. Generally speaking, the ball valves on the Febco backflows are female threads on both sides, which would mean that it is threaded onto the actual backflow unit, and the outlet pipe is threaded into the other end. I am not sure why a threaded fitting would be soldered, that just doesn't sound right. By the L-joint I assume you are talking about the elbow just after the outlet ball valve. You probably will need to replace all that in order to get the ball valve tight enough, unless you are using a compression type fitting or a union. Bottom line, you shouldn't be soldering a threaded fitting in any situation, sounds to me like the ball valve it either not tight enough, or it is cross threaded or stripped. Might be an ideal time to have a plumber come out and take a look at it. Its good that you wanted to give it a shot yourself, but this type of work is truly fit for a licensed plumber.
Tony Posey
Ridge Run Landscapes


Active Member


Wednesday, June 15th 2005, 4:20am

Just did this job (see posts). The assembly parts on mine were as follows:
1" copper from house(soldered)>elbow(threaded)>nipple(threaded)>ball valve(threaded)>febco(threaded)>ballvalve(threaded)>nipple(threaded)>elbow(soldered)>copper.
To do it right you have to desolder one end and start to dis-assemble up to the next solder joint. Then re-assemble and resolder. If you are trying to loosen and tighten without dis-assembling you have a crap shoot on your hands, the joints will never be as tight as they should be and will be prone to future leaks. I am not a licenced plumber but have replace plumbing in my house before and tried the crap shoot method, It worked for about 1-year then I had to do it the right way anyways!
Good Luck!

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