Capping Abandoned Domestic Coil Inlet/Outlet

John Oppenhimer

A boiler I was inspecting had an abandoned domestic coil(owner had recently upgraded to an indirect). The inlet and outlet pipes were cut and marguinally crimped leaving about a 2" stem projeting from the coil assembly faceplate.

1)With open pipes, some say that condensation or vapor within will be able to escape harmlessly, preventing pressure buildup should it superheat. They claim that "capping" the tubing (sweated copper caps)poses the threat of pressure buildup and potentially dangerous ejection of the caps, among other consequences.

Others say that leaving the tubing can permit system water to escape if the coil itself ruptures, corrodes or develops a pinhole, with the potential for running the boiler dry under certain circumstances, again, among other greater and lesser consequences.

My question is this: Is it not best practice to simply cut back or remove a section of the copper tubing to free the threaded coil receptacles, then install standard threaded plugs in those now empty receptacles on the faceplate? Does that not only contain any superheated condensation emanating from the coil as well as prevent escape of system water should the coil rupture or lose integrity?

Is there a definitive answer? Am I misguided? Any opinions or insight will help - and thanks to all who offer up info.

radioconnection_2

domestic coil

For what it is worth, I was told not to cap the domestic coil in my woodboiler to avoid possible pressure related safety concerns. I removed the coil, and then tightly capped the ports. I also put a note mentioning the coil was removed.

Pete

Norm Harvey

Ideally, remove the tankless plate, cut the coil out and sell it for scrap, then plug the holes and re-install the plate.

Otherwise, leave it un capped.

Thats my opinion.

Dave_4

The notion that...

somehow a coil, submerged in boiler water will somehow get enough pressure to blow caps - be they soldered on the existing stubs - or threaded on the adapter ends - is unfounded.

Where would such pressure come from? The water in the boiler won't get it there (probably on the order of 200 + PSI.) If the coil leaks, pressure on the inside will equal pressure on the outside.

I guess I agree with Norm in that "ideally"... I'd pull the coil and put on a blank plate. But "ideally" you will NOT find the bolts, mating surfaces the new blank would cover, or the bolts thereto "ideal."

Therein lies the problem. "Let sleeping dogs lie" sounds better all the time. True, the coil could corrode - although from what I have no idea. If this walled copper HWBB is in place, the pressure on them/it would be far more likely. Haven't seen that happen?

Neither have I. If you must, cap the stubs and leave it alone.

JMHO

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Maynard

coil

I Saw Soldered Joints Blow Apart On A Capped Coil...Leave The Ends Open.