Unrecognized return vent

pacoit · August 1

Hi,

I would like to identify the vent found on my radiator returns. See pics below.

Note: in the first pic, the second bump is actually the L of a second vent behind the first.

The vent has no identifying marks of any kind. It is 6" long. The bottom threaded hole is slightly more than a 1/4 NPT. The opening on the L is threaded. The L hole communicates with the bottom. However, on heating the vent, it did not close off air (perhaps broken). There is a rod and brass cap of the L; the rod has a threaded section, but sits loose in the inner hole. The the screw on the body is removed, the hole communicates with both the bottom and the L; when tightened, it is airtight. I hoped the body screw would loosen the inner parts; but it did not. It appears as if nothing more can be disassembled (but maybe there is a trick).

Some background on my system. It is an apparently uncommon 2-pipe system; each radiator has a separate runout from the main; each radiator has a separate return to the a common wet return near the floor of the basement; so, the returns do not communicate with each other; the radiators have generic supply valves (not indexable; no orifices); there are no traps at the radiator; there are vents at each radiator return, in the basement near the ceiling; all but two of the returns were updated with Hoffman 1A in the 1970s; the two remaining are as in the pics; there are no other vents or mechanical contraptions or special pipe arrangements, just the boiler.

The house was built in the 1910s; originally with a Pierce coal-fired boiler and radiators; a Kel-Mac vapor system is named in the blueprints. Circa 1924, the Pierce was replaced with a Bryant gas boiler. In 1997, it was replaced with a commodity Carrier (Dunkirk) gas boiler; existing near piping was unchanged.

System works well except for 2 of 20 radiators; one (furthest) rarely heats; the other (much closer to boiler), the supply pipe bangs a bit and radiator rarely heats. Neither have the old vent attached. Oddly, the two radiators with the old vent heat nicely.

I would also like to find more info on the Kel-Mac system. LAOSH only has a 1/2 page mention.

Thanks.

mattmia2 · August 2

early vents used a carbon rod that would expand in the steam, you might have some form of that.

mattmia2 · August 2

that 3/4 partition piece probably comes out or once came out when the screw in the side was removed. i don't see how you'd machine that in place. there might be something else that unscrews through the side ell port first.

EBEBRATT-Ed · August 2

If each radiators return is piped individually to a wet return then you need no traps. You should have an air vent large enough to vent the air from the supply run out through the radiator and the return line and the air vent should be located at the top of the riser where the return drops into the wet return

mattmia2 · August 2

https://forum.heatinghelp.com/discussion/comment/1861444#Comment_1861444

they have another thread with this system. that is what they have.

109A_5 · August 2

Since all the radiator condensate returns have their own vent and then drop down to a wet return, if there is not, a main vent at the far end of the steam main from the boiler may help. Also with the poor heating radiators and banging check the pipe pitch, there may be trapped condensate there.

" Oddly, the two radiators with the old vent heat nicely. " If it ain't broke don't fix it ???

Steamhead · August 3

@pacoit said- "The opening on the L is threaded"

My educated guess is this went to an air line that led to an ejector which pulled air from the system, similar to the Paul system. Or, it might have led to the chimney and used the draft to pull the air out, as in the Broomell and other systems.

Obviously, and regrettably, whatever was connected to this is long gone.

mattmia2 · August 3

https://forum.heatinghelp.com/discussion/comment/1861498#Comment_1861498

i think the system diagram has an air vent line. see the other thread.

pacoit · August 3

@Steamhead said, "My educated guess is this went to an air line that led to an ejector"

That is my guess as well. The threaded L hole seems perfect for an air line fitting. As @mattmia2 mentioned, the blue prints detail one indirect radiator under the living room floor; the outlet tees off (may not have been literal) with condensate return on one side and a "KelMac retarder" with "air-line" on other side. The KelMac retarder (probably adjustable) might well be the vent above.

Does anyone have a pic of a KelMac retarder? Or other info on KelMac system?

109A_5 · August 3

Looks like this post has 3 pictures of a Kelmac Jr. retarder. Looks like a steam trap, where is the valve assembly guts ?

https://forum.heatinghelp.com/discussion/150293/steam-trap-kelmac-jr-retarder

109A_5 · August 3

If I had to guess this screw is a calibration adjustment. When steam gets to it, it or what it screwed into expands to stops the steam from exiting the system, minimizing water consumption. It would not surprise me if it screwed into a bi-metal leaf spring.

The other slotted screw may have held the baffle assembly or the whole guts in place. The guts may be rusted in place now.

mattmia2 · August 3

that kel mac appears to be a different system with metering radiator valves and radiator traps.

109A_5 · August 3

https://forum.heatinghelp.com/discussion/comment/1861528#Comment_1861528

I agree it does, but the OP requested " Does anyone have a pic of a KelMac retarder? ". Maybe the KelMac retarder and the Kelmac Jr. retarder are different too.

JUGHNE · August 3

I believe I may have mentioned this previously.

I worked on a system that had "Kelmac Jr. Retarder" steam traps.

IIRC, the "Retarder" was 3/4" size and the "Jr." was 1/2" size.

The Kelmac valves left in the system were worn out and did not have any special designs for metering. Just a globe valve.

GI rad trap.jpg

GI kelmac valve 2.jpg

The guts had been removed from all traps.

Most valves changed and supply orifices added.

No return traps or drums left in basement.

System would run on ounces when done with changes.

pacoit · August 4

Thanks for the info!

I haven't been able to disassemble the vent beyond what is shown in the pics. What looks like an adjustment screw now fits loosely in the inner hole that it probably once screwed into, but is now rusted away a bit. As to the body screw, nothing inside came out when I removed it. So far, I have hesitated to bang on it (other than some tapping) until I (hopefully) find some more information.

I thought my old vent may have been the KelMac retarder. Apparently, it is a different component. My system has no trace of radiator traps; the return elbows look as old as the radiators. There is also no trace of KelMac radiator supply valves. Mine are apparently generic globe type; they have a big spring inside; and they are identified with an "S" inside of a triangle. The simple round, smooth, hard rubber handles look old (possibly going back to the 1924 switch to a Bryant gas boiler—-gas had just arrived to the city).

By the way, what is the proper way to repack these valves?

mattmia2 · August 4

might be sylphon.

how to repack depends on the type of valve. some use a bonnet with a packing gland in it, more premium valves used a bellows or some other "packless" arrangement.

109A_5 · August 4

Since you have it detached from the system and the threads on that bolt or what it screws into may be defective. If it were me, and it would be more for curiosity sake than repair, I would soak the old vent in a good rust remover and see if I could disassemble it some more. In the mean time I would just install another Hoffman 1A (or the like) in its place.

Those 2 old vents may have a vent rate much greater than a Hoffman 1A so to keep things balanced and venting as fast as practical a main vent may be a good idea if it does not already exist.

pacoit · August 4

@109A_5 , I'll try to de-rust / loosen the guts from the vent. I'm curious, too.

This is the radiator valve I'm trying to identify:

This is the guts. There is a stiff spring in the barrel. What is the proper way to pack this?

mattmia2 · August 4

do you see packing in the bottom of the bonnet above that disc on the upper half of the stem?

it will probably be a lot easier to see what is going on if you take the handle off and take the bonnet off and it will be easier to replace the packing without the stem through it.

packing material frequently contained asbestos, frequently graphite coated, though it could be other fibers too.

It looks like it is a non-rising stem globe valve with conventional packing but it could be something else.

Steamhead · August 4

That's a "spring-packed" valve. ISTR the washer on the stem compresses the spring against the packing which is located underneath the spring. Replacement packing would look like a washer with a hole in it the size of the stem.

Also, the stem is non-rising and has no threads on it. It engages with the threaded portion at the left, which runs in threads inside the bonnet (or sometimes in the valve body) to open and close the valve. This puts less wear on the packing, and is one reason these valves last as long as they do.

Not sure what the S stands for though.

mattmia2 · August 4

You could probably use string packing if you can't find a suitable packing washer although you might need to initially press it together with your hand and the stem on a table or some socket or pieces of pipe and a vise to pack the new packing together.

mattmia2 · August 4

The radiator has an offset bushing in it. Not important for the supply but helps the radiator drain better on the return.

pacoit · 12:50AM

@mattmia2 , Yes, there was some tiny residue of packing on the top side of the disk (at arrow). I previously removed the handle; the screw cap slides out and there is nothing else.

@Steamhead , I didn't quite follow your description as to the washer position. You are correct that the stem is non-rising.

It appears to me that the packing/washer should fill the space at the arrow; the screw cap presses down from the top; and the spring in the "barrel" presses up against the the bottom of the disk. Is that correct?

Steamhead · 1:17AM

@pacoit , it looks like there is a washer below and slightly left of the arrow that says "pack here?". It also might be part of a sleeve. That should be what compresses the spring. Is there any evidence of packing material below the spring?

pacoit · 2:39AM

@Steamhead , Ah, the "disk" just left of the arrow is a solid part of the stem; the spring presses up against it; cap screw and packing press down. The bottom of the (very stiff) spring is fixed in the "barrel". I see no evidence of, and no place for, packing below the spring.

My guess is that the spring provides a little flexibility so that the amount of packing doesn't have to be exact and still allow the screw cap to be screwed all the way in.

I found a small amount of thin string in one valve (at arrow location). I tried twisting 3 strands of that thicker blue thread tape to form a ~1/8" string. It worked on several valves, but one valve has failed twice despite heavy packing (I'm running roughly 0.5 psi air in the system to find leaks.).

mattmia2 · 2:51AM

the spring does come out, might have to twist it in the direction that makes it smaller to get it to move but you don't have to remove it. try some small string packing and try using a vise with some blocks of wood or a c clamp and wood, one with a hole in it to use that shoulder on the stem to pack the string packing together. i'd probably use teflon, once you get it in there it will last forever. if the stem is rough where the packing rides on it, polish it with fine scotchbrite. mcmaster carr sells spools of all sorts of string packing.

Unrecognized return vent

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