OK, I give...

marc

the hemp that Viessmann sends with their boilers is for threads, it works great. it takes a while for the hemp to work, it gets wet then swells up and stops the leak. I have talked with waterworks companies and they use hemp on all large threaded piping. marc

Howie_3

Threaded connections give me a headache...

Give me your best advice to get threaded connections leak free. I've been trying to get the top connection of my Viessmann 3-way mixing valve leak free, and I can't seem to make it happen. (Fortunately, there is one of those screw on grudfos pump fittings very near this connection.) I keep getting a pinhole leak (under 80 psi water pressure, a drop of water will form... I realize it will never be under this kind of pressure in real life, but don't you guys always test at high pressure?) always in the same location at the first exposed area where the threads meet. I've tried various numbers of wrappings of teflon. Should I have used the horsehair(?)/dope combination that comes with many Viessmann threaded fittings? Teflon w/ dope? Just dope? How much torque? Hand tight plus a 1/4 turn? More?

I swear, this is an art.

bob_50

Leak

You are probably fighting some of those funky furin threads. Take it apart, clean both the male and female threads (CLEAN) put five minute epoxy on the threads, let it cure and forget about it.

Scott Kneeland

Expando works well too. If you have redoped this fitting several times and tightened it you may of streched the fitting also.

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Just a HO

Slave Labor

When I was a kid slave laboring in my fathers hydraulic machine shop, we weren't allowed to use teflon tape. I was always told if a little piece of tape gets in the system it will chew apart the pumps. We always used liquid "pipe dope" or risk the wrath of my father.

I was also always told that the pipe dope didn't so much prevent leaks, but it provided lubrication so that the connection could be tightened properly and the tightness prevented leaking.

His shop was full of older, season guys that all said the same thing. What do you pro's say....are these old wive's tales?

I'm curious, how many of you pro's started as child labor for your father? When I was 6 years old threading pipe on the "rigid" for hours at a time it didn't seem like fun....but now they are fond memories!

bob young

PERMATEX

permatex and lampwick , tighten w/ proper wrenches. no leaks , ever. END OF STORY

ALH_4

Once

I once had a Viessmann mixing valve that had some messed up threads. It was barely visible, but the half coupler welded to the valve was damaged. It would not seal. We tried everything. We finally sent it back and got another. What a headache that was.

-Andrew

Mike T., Swampeast MO

80 psi? Granted not high for domestic water but for a hydronic system when you get a tiny pregnant drop...

Howie_3

really?

Maybe if both sides were inexpensive fittings, but not on the Viessmann 3-way.

Howie_3

Related frustration...

I should have mentioned that I'm also having bad luck with CxCxF copper tees. I'm on my second tee that has a pinhole leak in the area where the F meets the C. Last one I replaced, but is there some kind of repair that can be made to these? I remember in another thread someone mentioned something-weld. Would something like that work?

bob young

fielder's choice

Hit it with the torch or rip it out and start over. you seem to be having a tough time with fitting pipe. maybe you should hire a plumber and stick to your normal line of work. much less agravation , no ?

marc

Hemp

Use the hemp on the pipe threads, it will leak for a short time then stop leaking, kinda a pain in the a&% to put on the threads, try a very small amount of pipe dope to give the hemp something to stick to, then wrap around threads and screw together the connection. Use small amounts of the hemp, it looks ugly with all the hair hanging from the pipe, after the connection has stopped weeping, you can burn the hemp off with a torch, just dont inhale! marc

Rodney Summers

you mean you would wish this aggravation on a poor plumber?

:-)

Plumdog_2

your kidding, right?

Hemp, pipe dope, don't inhale? Election year coming up?

Plumdog_2

hand tight

depends on whose hand your talking about. Magilla the Gorilla could split 2 inch gas pipe fittings with a 16 inch wrench. Once he broke the handle off a 18 inch wrench. But 1/4 turn past hand tight is not near enough. Get some extra fittings and crank them together till they split; then you will know what too tight is. Don't split the Viessman, however; as this is a costly screw-up so to speak.

Howie_3

Hemp... yes!

The hemp worked like a champ. If I had a clue, I would have used it from the start. I used a little Gasoila pipe dope lightly to stick the hemp, then some hemp into the threads, no weeping, then burn off the extra.

Thanks Marc!

Howie