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Rongold Member Posts: 21
edited May 2021 in Oil Heating
Hi all,

I had to replace a leaking immersion well in my Weil McLain WGO6 boiler, as it had started leaking internally and liquid got in the control box and shorted it out. The system had 20 year old boiler anti freeze in it, so I dumped the whole thing and flushed out the boiler and all 3 zones. I now want to replace the 33 year old pressure relief valve, but I am having trouble breaking the union in the exhaust line apart. I think my problem is the size of the pipe wrenches I am using---a 6" and a 10"--I don't think I am getting enough leverage. I have a 14", an 18" and a 24" coming from Ebay--All good used Ridgid. I have included 3 pictures for you to look at. The first picture shows what I call the "open end" of the union. The second shows a side view, and the third picture shows the "closed end". Looking at the first picture, I put the big pipe wrench on from the angle the picture was taken, and I lift, trying to turn the union nut clockwise. The smaller pipe wrench is on the hex in front of the union keeping pressure in the down or counter clockwise direction. As far as I know, that is the direction to loosen the big nut. I don't think there is such a thing as a left handed union---Is there ??? Am I trying to turn in the proper direction ??? As I said before, I think my problem is the small size of the wrenches I am using. This is not big pipe---It's 3/4" copper !!!




  • BillyO
    BillyO Member Posts: 277
    probably soldered together from initial install
  • Zman
    Zman Member Posts: 7,569
    From the looks of the scars on the pipe, I think you are turning it the right way.
    You could try using some pipes as wrench extensions. Applying heat to the nut will help break the bond, if you apply too much heat, you will break the solder joints (and solder in threads if @BillyO is correct).

    If you are going to bother to get a torch out, you could just unsweat the fitting and solder it back together when you are done...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • pecmsg
    pecmsg Member Posts: 4,852
    A 6" pipe wrench is a toy!

    2) 18" or 24" wrenches minimum.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    Cut it out.
    EBEBRATT-Ed Member Posts: 15,527
    They may have soldered it together as @BillyO mentioned. Get two hammers a big one and a small one. Put the big hammer behind the union nut and hold it pressed tight to the nut. Rap the nut from the other side a couple of times with the other hammer. If it's not soldered together it will come apart.
  • jacobsond
    jacobsond Member Posts: 90
    what eberatt said. Ive taken cast unions apart that look a whole lot worse than that. Might need more than a tap but it will stretch and loosen the threads.
    coming to you from warm and sunny ND
    Dave T_2
  • 426hemi
    426hemi Member Posts: 79
    Just sweat a new union in why waste time trying to get it apart time is money! 
    Dave T_2iPipefitterSTEVEusaPA
  • iPipefitter
    iPipefitter Member Posts: 15
    In my experience I use 18" or 24" pipe wrenches on unions that are fed by steam, also breaker bars for more torque. Also, you could try hitting the union base with a hammer, they may not have used anti-seize on the union which makes it much harder to get apart. I know this is different than steam but you could give it a shot.
  • mattmia2
    mattmia2 Member Posts: 9,653
    keep in mind the union is about 2 pipe sizes larger than the pipe itself.
  • Rongold
    Rongold Member Posts: 21
    Thank you all for your help & comments. I got my used Ridged 14" & 18" pipe wrenches today, and held the union hex with the 14" and put the 18" wrench on the union nut. I gave it a smack to shock it, and then one good push on the 18" wrench and it finally turned. I will put anti sieze grease on the threads when I reassemble it. I knew I was turning it in the right direction !!!

  • Big Ed_4
    Big Ed_4 Member Posts: 2,785
    Just use a soft set paste pipe dope on the union threads as a lubricant .
    I have enough experience to know , that I dont know it all