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-   -   Stripped Water Heater Threads (http://www.diychatroom.com/f2/stripped-water-heater-threads-123343/)

JLC5959 11-13-2011 05:59 PM

Stripped Water Heater Threads
 
Hi All,
I am new to the site but I have really got myself in between a rock and a hardspot. My hot water heater relief valve was dripping. The valve is mounted on the side near the top. I drained the tank and removed the old one. I then put tape on the threads and installed the new one. This is when things went south. I some how sucessfully managed to install the new one but have stripped the threads on it. It spins freely. I cannot remove it. It has to come out so I can try to put a new one in. I am guessing the threads on the valve are messed up. It is a newer gas 50 gallon tank so I hate to scrap this one. Any advice on a way to remove the valve with stripped threads.

ben's plumbing 11-13-2011 06:07 PM

this has only happened once in 30yrs for us we got a call from homeowner for the same thing..my tech tried turning and pulling at same time ..over and over did not work.....I cut relief valve off with sawall and cut inner threads with saw and was able to pry out....brass valve was stripped....hope this helps....ben......some one may have another idea.....hang tight..

JLC5959 11-13-2011 06:13 PM

Stripped Threads
 
Thanks for the reply. I have tried and tried turning and pulling untill I was blue in the face. Sounds like that was the obvious path. How did you cut inner threads? What inner threads did you cut? Threads on bronze releif valve?

Josh

ben's plumbing 11-13-2011 06:20 PM

after i cut off relief valve you could see where brass was screwed in heater i then used a mini hacksaw an gently sawed at the brass threads until i just hit the threads of the heater.....BE CAREFUL NOT TO DAMAGE THREADS ON HEATER...brass cuts easy cut slowly.....yes the inner threads of valve

Daniel Holzman 11-13-2011 06:56 PM

There is a high probability you are going to damage the threads of the water heater during this extraction project. If this happens, there is an outside chance you can overdrill the hole, tap the new hole for the next larger set of NPT threads, and install a larger valve. This assumes you can get a larger valve, and you want to invest in the drill and tap set for a larger valve. I did this once on a boiler, it was pretty dicey. It worked, but I have little confidence in the method, just a thought.

Thurman 11-14-2011 12:13 PM

With all due respect to Dan's many post's on here with his knowledge, but with my experience with working with pipe and water heates/boilers: I seriously doubt that the 3/4" FNPT threads in a water heater for the T&P valve could be drilled out to the next size, being 1" FNPT. Most water heaters, in my experience, have a "spud" welded into the side/top of the tank with pre-cut threads to accept the T&P valve. This spud does not have enough meat in the side-wall to drill out to accept a 1" NPT tap. The post from "Ben" is the one which would be the most commonly accepted practice by most plumber's for this problem. It is correct that care/caution should be taken when cutting the remaining threads of the T&P valve so as not to damage the iron threads of the "spud" which the T&P valve screws into. Pulling on the existing T&P valve while turning in the direction as to unscrew it should cause it to come out.

JLC5959 11-14-2011 06:05 PM

Wow, What a mess
 
Guys, I tore it down today and got after it. Ben I took most of your advice. I took a hacksaw and cut the valve back flush with the tank. I then took a large drill bit and drilled out the guts of the valve. I then sawed the valve in 3 pieces with a mini hacksaw. What I found out was that I didnt strip the new valve when I installed it. When I installed the new valve, I turned in too far and ran the threads of the valve past the threads on the water heater. The threads were hanging in the tank. For what ever reason it would not line back up and start to unscrew it. Trust me I turned and turned. I ended up having to hammer the sawed pices of the valve into the tank. As hard as I tried, I had screwed up the threads on the water heater. Daniel-you called that! I just ran a 3/4" tap and cleaned up the threads. I didnt change thread sizes. I then bought a new valve and in threaded in PERFECT! Filled the tank up with water and we are back in business. I have a happy wife. The only problem is the old valve is inside the tank, but I guess that is ok! Total I spent $45 on the repair. A new tank would of been $500 for a 50 gallow gas heater. Not sure how much a plumber would of charged. Guys thanks for your help!

ben's plumbing 11-14-2011 06:25 PM

great..always nice to see success on a project that saves money.....Ben

Daniel Holzman 11-14-2011 06:37 PM

Thurman, that was a useful observation about the spud on the inside of the tank. In the case where I successfully overdrilled the hole, it was on a boiler where the insert was installed directly into the steel plate, and overdrilling was possible. I still have the (expensive) drill and more expensive tap I used, probably will never use it again, but I did not realize a spud was used on water heaters.


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