thread sealant

PDB2

In hydronic near boiler piping, is there a preferred type/brand to use

when mating copper to black iron? Or for that matter, a certain type for

all hydronic connections?

Snowmelt

What I use

Pro dope

kcopp

I really like....

Blue-Magic by Whitlam

http://www.jcwhitlam.com/plumb/productdetail.aspx?selected=1&industry=1&group=no&subcat_id=65&name=Blue Magic

jumper

technique can matter too

especially with cheater thread

lza

pipe dope

PDB2



Anything you use will be fine.  I personally use Hercules umm...Megaloc.  I like the consistency.  But pretty much anything will work (and my personal preference for application is a thin layer of dope, then a three wraps of teflon tape, then another thin layer of dope).  The one thing I would advise you on is your choice of fittings.  If you use dielectrics, stay away from dielectric unions as they tend to leak.  If you use a dielectric nipple, I personally always use a brass coupling and then a copper male adapter.  Copper female adapters tend to leak at the threaded joint. 

lza

cheater thread?

jumper,



What is cheater thread?

hot_rod

I really like

this 3- Wrap tape from Mill Rose. You really do not need to add any dope with it. Great for rough threads, and comes off the roll better, to the very end.

bob_46

Cast Iron

The use of teflon tape or paste is not recommended for connections on cast iron baseboard or cast iron headers on coils . It is too easy to over tighten and crack the casting .

RobG

If

If done correctly there is no problem with mating copper to CI baseboard with Teflon or paste, as long as there is room for linear expansion. At least I've never had a problem.





And if you don't use Teflon or paste how are you going to seal the joint?

Rob