View Full Version : Dilelectric Union Won't Budge

11-10-2010, 04:39 AM
My P-203 boilers Dielectric Union is leaking badly. So I turned off everything and drained the system...now I'm trying to get it off with a plumbers wrench and it won't budge. Any, suggestions?

I'm a newbie with a wrench...so any insight would be appreciated!



11-10-2010, 06:21 PM
Try penetrating oil, heating with a torch or cut/grind the thing into pieces. JC Whitney sells arbor mounted abrasive wheels 1/16" thick for your elec. drill that can cut stuff like this.

Strangely enough, sometimes tightening the thing 1/4th or 1/8th turn, and then loosening, works.

11-11-2010, 01:22 AM
Thank you my friend for the prompt reply! I will try all of that quickly...and will let you know which one worked!

11-23-2010, 07:51 PM
That looks horrible. Be prepared for the whole thing to fall apart. Maybe try some plumbers epoxy to stop the leak and then fix it properly after the heating season ends.

11-23-2010, 09:25 PM
Does "plumbers" epoxy stick to rust?

I've never seen a plumber use epoxy for a leak.
If you use a torch to loosen the fitting, place the flame on the fitting, not the pipe.

11-24-2010, 09:32 AM
Thank you my friend for the prompt reply! I will try all of that quickly...and will let you know which one worked!
You're welcome.

The tightening thing I learned trying to pry up a sewer drain cover.
It wouldn't budge with maximum leverage so I whacked it further onto the pipe with my 48 oz. hammer and it came right out.

Same with windows that are painted shut.
No window is closed all the way, so whack it down one good one on each side using a wood block under the hammer to prevent marring the window.

11-25-2010, 07:52 AM
If something is so tight it will not loosen, I have NEVER found that there is "room" to tighten it further. Friction fit items WILL respond to movement, and sometimes vibration, since they are seldom at the "bottom" of their travel. That particular union is probably beyond salvation. Beating on it with opposing hammers, might dislodge some of the rust in the threads, but more than likely this is a job for a SawZall and a new union.

11-25-2010, 04:58 PM
How long has it been leaking? By the looks I'm guessing this isn't new. Could mean other issue for your boiler. They don't like leaks b/c that means more fresh water (with O2) being added to the system. This creates corrosion(rust) in other parts including rusting out the boiler and circulator pumps.

If you do end up replacing that union with a new one it prob wouldn't hurt having your system flushed out and/or have some rust inhibitor added into the boiler. From what I can see in the pic it looks like a Burnham that is >25yrs old(my guess). Worth trying to save and get more years of life out of it. IMO