Do I need to cap both ends of hydronic radiator?

[gadolphus32]

I have an old cast-iron radiator in my attic. It has a leaky valve, which I tried to replace but I can't find the right size (I'm wondering if the thing is so old that it is a non-standard size, because no standard valve that I have tried works to connect to the radiator...although the pipe coming into the system is a standard 1-inch).

No one lives in my attic, so I was just going to cap this radiator off and be done with it.

My question is whether I can cap just the pipe that feeds water into the radiator, or if I need to cap the other end, too. The supply end will be super easy to cap, because I already removed the valve. The pipe on the other side is much more difficult to deal with because of access issues, and I am worried that if I start moving things around too much on that pipe, I'll break connections somewhere else in the system. So I'd just as soon leave that other end be if I can.

The radiator currently has no water in it. I assume that if I cap just the supply pipe so that no more water can come up to that part of the system, there is no need to cap the return side. But I thought I'd check with you professionals before I make a dumb assumption.

In case it's not clear, this is a hot water (not steam) system. The radiator in question is the only one in the attic, and the highest point in the system.

 

[hj]

As long as you do not add water to the system it will not leak, but as soon as you refill it water WILL pour out of the radiator. You are having a problem with the valve because the inlet pipe is a standard size, but the union nut is whatever the manufacturer made it. You have to also remove the brass piece from the radiator and get a new hot water radiator valve.

 

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[gadolphus32]

Thanks. So water can flow in both directions through the pipe, then? I assumed it only flowed one way and if I cut off the "in" pipe that feeds the radiator, no water could come out the other side.

Follow-up question: If I were to use a sawzall to cut the "out" pipe where it comes up from the floor, is there a compression fitting that I could then use to cap that pipe without having threads available on that side? I think my radiator supply pipes are galvanized and I'm not clear on whether you can use compression fittings as a permanent fix with galvanized pipe.

Being able to cut the pipe at the floor and cap it with a compression fitting would save the trouble and risk of trying to remove the elbow that currently connects that pipe to the radiator.

The leaky valve issue wasn't actually related to the fitting that won't fit, by the way. Water leaked out from under the packing nut that held the valve stem in place. I tried tightening, straightening the stem, banging the stem back down, etc. but nothing stopped the leak. I think the part is just shot. I used JB Weld to keep it from leaking all last winter (I know -- not a brilliant idea, but it worked, luckily), and am now trying to solve this in a permanent way before I have to turn the system back on for the winter.

 

[Dana]

The system is always under pressure sufficient to raise the water to the top radiator (with some margin). While a pump determines the direction of the flow, both the supply & return are pressurized, and water will flow out of the return end when the system is filled.

Cutting and capping only works if that radiator is it's own micro-zone. Most systems have multiple radiators plumbed in series- the outflow from one radiator is the supply to the next one in the chain. If you cap it off you'll lose flow to the entire zone, not just that radiator. But there are many variations on the theme (monoflow tees, or other types of radiator-bypass branch plumbing, etc.) where it MIGHT work.

Can you post some pictures of the connection plumbing to the radiator (both ends)?

 

[gadolphus32]

Here's a link to a picture of the line going in, with the valve removed:
https://drive.google.com/open?id=0B7bXIkUCzMbxWE9EZkVKWTdJOTg

The new valve that I bought is on the floor in that picture, alongside the brass connector that came with it. The bushing on this connector is not quite the same size as the one for the brass connector that is currently attached to the radiator. I'm not sure how to get the current connector off. I can't get a pipe wrench on it because the bushing is in the way. Should I cut it to the point where I could pull the bushing off, then use a wrench to screw off the rest of the pipe?

And here's a picture of the line going out. I have no idea how I'd take the elbow off in order to cap that pipe. I can't turn the elbow at either end because of the connection on the opposite end. My only thought is to cut the elbow in half, then twist it off.

Thanks for your help. I appreciate it.

 

[Dana]

Cut the reducer on far end of of the radiator with a sawzall hacksaw blade and it should be possible to remove the reducer &/or nipple (which ever frees up first), and pull the radiator aside.

With the radiator out of the way it leaves room to plumb in a section of pipe where the radiator once stood, with an ell where the valve had been, and a union in the middle. ( Or, just cap both ends and test to see if the zones still work, adding the bypass pipe only if it's necessary.)

 

[gadolphus32]

Dumb question, but what do you mean by reducer? Do you mean the piece between the elbow and the radiator in the second picture?

 

[Dana]

I should properly have said "bushing", or "hex bushing", not "reducer". (Sorry- I'm being bit sloppy today. I need more coffee! ). It' is the threaded part that's threaded directly into the radiator. It has a larger diameter thread than the threaded nipple between that piece and the ell.

If cut as near as possible to the hex head there will still be enough to grab on to to remove the rest of the bushing from the radiator. If you can get it to turn even 1/10 of a turn prior to cutting it, removing the remainder from the radiator will be easier. Hopefully there was enough pipe-dope used when it was installed that it's isn't solidly rusted together. (It's usually possible to unscrew the stuff even when it's pretty crusty-rusty on the exterior.)

Of course you COULD see if you can't get the piece on the valve end of the rad to turn (sometimes it's hard to get a wench on it with with the dangling loose valve-mating piece on it) and replace it with something that works with a new valve, but cutting off the brass piece would provide more wrench-room for pulling the bushing.

 

[gadolphus32]

Thanks for all your help. I was able to remove the radiator and get both lines down to where I can cap them.

And yet, the saga continues...

My caps don't quite fit on. I tried 1-inch caps (which by all indications is what this should be) and they're just a tiny, tiny bit too small to screw on. I can't get the threads to take, no matter what I do. I also tried 1.25-inch caps and they're way too big. As far as I know, there's no standard size between 1 inch and 1.25 inches.

I tried multiple caps, in case one was bad. And the problem occurs with both of the pipes I am trying to cap, so I don't think the issue is that the pipes got deformed. (They would have both had to be deformed and that seems unlikely -- plus they look fine: threads intact, etc.).

So it seems like the pipes I have coming out of the floor are either not exactly 1-inch, or are threaded in a way that makes the caps I have not work with them. I guess now I'm getting into a different sort of problem than the one I originally posted here about. But any advice would be appreciated. Is this a problem that occurs commonly when attaching fittings to old pipes (my house was built in 1910 and I assume this is original plumbing)? Is there any kind of compression fitting that I could put onto these pipes to cap them reliably without using the threads? Is there a way even just to solder them closed, or something like that?

All I want is a way to cap these things so I never have to think about them (or lie awake on vacation worrying that a leaky attic radiator is destroying the lower two floors of my house while no one is home) again.

 

[hj]

Cut the pipe between the elbow and bushing. Then you can unscrew the elbow and put a cap on the pipe. I don't know what your problem is, but those ARE standard size pipes, probably 1", and they NEVER made any sizes between 1" and 1 1/4", or between any other standard sizes for that matter.

 

[gadolphus32]

Cut the pipe between the elbow and bushing. Then you can unscrew the elbow and put a cap on the pipe.

That's what I did, but the caps don't fit. I'm dumb at a lot of things but I would like to think not so dumb that I can't screw on caps!

Everything about this radiator has seemed to be non-standard. For all I know they imported it from Europe or something and it's metric measurements. It's weird.

Is there no way to put a compression fitting on these pipes?

 

[hj]

Like I said, "I don't know what your problem is", but those ARE standard U.S.A. threads. If it were metric, the whole system would have to be metric because the two measuring systems are not interchangeable.

 

[gadolphus32]

Well, I guess I'll try different caps then. And maybe cleaning the threads. The strange thing is that the old radiator valve screws right onto both pipes, with no problem. But I can't get the caps to take no matter what. Maybe they are a bad set.

It would still be helpful to know if compression fittings are a backup option. I believe (though am not certain) that these pipes are galvanized, though most of the coating seems to be worn off/replaced with rust at this point. Can you compression-fit galvanized pipes? The only thing I have found online for that scenario is stuff like this: https://www.plumbingsupply.com/galvanized-compression-fittings.html

 

[Reach4]

Well, I guess I'll try different caps then.

Measure the OD of the pipe you are trying to cap, with your digital caliper. No digital caliper? Go to HF.

 

[hj]

They SELDOM used galvanized pipe for heating systems. Yours is black pipe, but that has NOTHING to do with the thread size. Even if you COULD use a compression coupling, you would still have to knew WHAT SIZE THE PIPE IS. How about a picture of your caps with any printing on them? (Rach4; Who, what, or WHERE is HF?)

 

[Reach4]

Harbor ...

3329 East Bell RD STE 9, Phoenix, AZ 85032 in Plaza de Campana or 4925 W. Bell RD, STE C8, Glendale, AZ 85308.

 

[gadolphus32]

There is a pipe that is capped that comes up out of the attic floor a few feet from the radiator. An abandoned expansion tank hangs above it, and I assume this capped pipe used to feed that tank. That pipe has a cap on it that says just "J. P. Ward" (nothing else) and looks like this:

This pipe looks to be the same diameter and threading as the two radiator pipes I am dealing with.

I'm not a professional, but that looks like a galvanized cap to me. (And a plumber told me that I had galvanized radiator lines with cast-iron fittings, though maybe he was wrong.) It also looks like they sealed up around the bottom of the cap with lead or something like that. (That droopy stuff that you can see covering part of the threads is rock hard.) Assuming this type of cap is the same as what I need for the radiator pipes, does this provide any clues?

I'm waiting for a chance to go pick up new caps at the plumbing store, where I'll also ask about this to see if anyone has local experience with caps not fitting on old plumbing in this city. Probably won't be able to get to the store till tomorrow, though.

 

[Reach4]

I'm waiting for a chance to go pick up new caps at the plumbing store,

Does measuring seem that hard? If you are not going to get a digital caliper, how about getting a tape measure at a sewing store. Tell us the distance around (circumpherance) and we can interpret it for you.

 

[gadolphus32]

The outside diameter is 1.25 inches. The circumference is 4.5, for what that's worth.

 

[Reach4]

The outside diameter is 1.25 inches. The circumference is 4.5, for what that's worth.

Circuference 4.5 is diameter 1.43.

1 inch pipe is 1.315 OD.

http://www.engineeringtoolbox.com/ansi-steel-pipes-d_305.html