Existing copper piping to rads in 1-pipe steam; black pipe charts?

SteamFTW

Before anyone gets excited: I'm NOT asking in order to install copper. I'm inspecting an existing 1-pipe steam system that has water (and sometimes hammer) in a CI rad. In checking the pipes from the main to the rad valve, I found that they're all copper. IMHO the cause is the undersized rad valve, which maxxes out at only 62.5% of the EDR of the rad. But this scenario got me thinking:

How applicable are the 1-pipe steam charts for black pipe, when you find copper instead? I mean: if you want to determine whether the existing copper pipes can handle the connected load. I feel like I read something about this once before (probably here) but I can't find it now. HO is worried the walls and floor will have to be opened up to replace the existing copper.

Many thanks

Jamie Hall

It's mostly a matter of diameter, so the black iron charts should work pretty well. Unless a particular more or less horizontal run is giving trouble I'd not worry.

EBEBRATT-Ed

I" copper is about 1" Id . Black pipe is slightly larger. Probably not much difference in the other pipe sizes. If we were talking a long run it might change things

The difference on a radiator run out is probably negligible.

Are you saying the radiator valve are smaller than the runouts? Or are the valves and runouts undersized?

SteamFTW

Jamie Hall said:

It's mostly a matter of diameter, so the black iron charts should work pretty well. Unless a particular more or less horizontal run is giving trouble I'd not worry.

Thank you. I was hoping for that answer. If putting in a rad valve that can handle the load of the radiator doesn't settle things down, I'll post a full assessment of the scenario.

EBEBRATT-Ed said:

...If we were talking a long run it might change things...Are you saying the radiator valve are smaller than the runouts? Or are the valves and runouts undersized?

Just the valve. According to the charts, at first glance the pipes should be able to carry the EDR load with plenty to spare. The rad valve: no way! I will be returning to check on the usual gotchas, which (if they're there) will still be there after removing the restriction at the radiator.

#1 "Is the run-out is more than 8' long?"
#2 "Does the riser serve radiation on the second (or higher) floor?"
#3 "Can you get enough pitch?"
#4 "Is the riser dripped?"

Since you mention "a long run might change things", do you mean specifically a long run of copper?

Thanks for your insights.

Steamhead

Another question: if someone replaced iron pipe with copper, did they reduce the pipe size? This would probably fly for water piping, but not for steam.

Mad Dog_2

The difference is negligible.  Although not ideal, copper & copper joints on steam radiator take offs and branches were very common and can hold up for many years. I had a consultation and repair out of town about 20 yrs ago on a Botched Two Pipe Steam System. The plumber's Copper work was pretty good, sized properly..he just had no clue about Loop Seals and traps et cetera.

After studying the system, it was a pretty easy fix..one 8 hour day with copper. Black pipe and Steam fittings would take me double to triple the time AND now he'd have a Frankenstein System with black steel and copper. He had done his reading 📚 about Copper and Steam, so he was all nervous 😓 😬 😅 like Steam Police 🚔 were coming...I had to personally guarantee him that if ANY of my joints leaked, I'd come back Pro Bono..Never got that call!  Sometimes, you've got to offer the practical, more reasonable options 😉.  Mad Dog 

SteamFTW

Steamhead said:

Another question: if someone replaced iron pipe with copper, did they reduce the pipe size? This would probably fly for water piping, but not for steam.

Yes, good point, especially when there may have been significant "re-modelling". Thank you.

Jamie Hall said:

...Unless a particular more or less horizontal run is giving trouble...

Bingo!

I was able to get my camera into the horizontal pipe under the floor. It was at least 35% full of water, even when the system was cold. Raising the radiator considerably made the water level drop considerably. Now it's only about 7-10% full. The hammer is gone! The radiator still heats up slower than it should, but it's much better than it was: good enough for them to call off open-wall/floor surgery.

Coincidentally(?), the place where we just moved has a less simple version of this problem. To keep this thread focused on the original question, which I think has been answered (thank you, all!), I'm going to start a separate one for that.