Radiator below waterline on 1PS system

Nick_Castrads

I visited a client's home in New Jersey yesterday. One pipe system, so far so normal.

The boiler is located on the ground floor (there's no basement). At the same level there's a (later addition) radiator with a pipe running into the top left and a second pipe running out of the bottom right. There's also a bleed valve on the radiator where you'd normally see the vent.

I thought it looked strange, figured it must be below the water line, opened the bleed valve and sure enough water came out.

My question is: is this normal? I've never seen a radiator below the waterline on a steam system before. It's a much later radiator than the others in the house (mostly Cortos) - is it a hack job that should be removed? If we supply a new radiator to replace it, will it cause more issues?

Here's a very rough sketch of what I believe the system looks like.

Thanks in advance!

Nick

Alan (California Radiant) Forbes

I would think the radiator never gets hot without a pump.

ARobertson13

Nick_Castrads, I believe this arrangement is a variant of what Holohan called a "Brooklyn Special" He mentioned this about 7 years ago.

dko

https://forum.heatinghelp.com/discussion/comment/1806037#Comment_1806037

https://www.heatinghelp.com/news-and-media/dead-men-tales/how-one-missing-pipe-can-make-all-the-difference/

mattmia2

I'm betting it doesn't heat unless you open that bleeder and wait for steam to come out and then it bangs a lot.

At first I thought someone had arranged it as a gravity hot water zone where they got the tappings below the water line low and high enough to get gravity circulation but I can't see how it works with overhead steam feeding it without some sort of mechanical or steam powered return pump to push the water in to the boiler.

EBEBRATT-Ed

It may get warm it is just heated by condensate it will never get any steam. So it will see condensate temp only.

For that to steam a condensate pump and a trap would have to be added. Or add a rad on the ceiling if you have enough height

mattmia2

https://forum.heatinghelp.com/discussion/comment/1806046#Comment_1806046

I don't think the condensate is even going to get warm, both connections would have to be below the water line for that to happen.

Unless. Where does that overhead pipe come from, is it from a steam main or is it a return, does the hot condensate from the system above fall in to that radiator?

Steamhead

The overhead pipe might be the condensate drip from the steam main. This setup would heat that rad with hot condensate as it works its way back to the boiler. We have a couple customers with setups like this.

CLamb

The big question is how well does it work.

Nick_Castrads

@ARobertson13 @dko thanks very much. Really useful.

Nick_Castrads

@mattmia2 @Steamhead the overhead pipe connects directly to the steam main (which is just the other side of that wall behind the radiator) - so yes, Steamhead you're right, to the best of my knowledge it's the condensate drip from the steam main. I did think this would be the case.

To your point @CLamb I couldn't speak to how well it works from personal experience but the client certainly didn't complain of being cold. She also didn't complain of any steam hammer.

@EBEBRATT-Ed, client is reluctant to change any piping and wants to put the new radiator pretty much where it is already. I did suggest moving the radiator up higher above the waterline but she wasn't keen.

I'm planning to put the same configuration back in (on a new radiator), insert an ⅛" bleed valve into the vent hole and pretty much otherwise leave well alone. My fear was that it'll just not work but it seems from your comments that although sub-prime, it's not going to land us in hot water (ha ha ha).

Does that sound about right?

mattmia2

I think that radiator was salvaged from somewhere else and just had a bleeder on it, I don't think it is necessary for it to work. The radiator should fill to the water line of the boiler and the air vent out through the mains and vents on the system until it is full to the water line.

Be careful about giving them a replacement with similar EDR. The part that is below the water line is what will heat and its output will only be whatever the hot water output of that area is at whatever temp the condensate is. Might be important that it has similar volume below the water line.

It is going to be cold until enough condensate has been produced by the system so it will heat a significant time after the system heats and stay warm after the system shuts off (or maybe just stay warm the whole time depending on what the cycle rate and duration of the system looks like).

Since there is no place for the air to vent out at the radiator, that riser to the main will trap a column of air and keep steam from getting to the water in the radiator and causing water hammer.

If you were to move the radiator above the water line that would require re-engineering of how it is connected to the system so that it can get steam and get rid of condensate without the condensate from the system running through it and possibly doing a 2 pipe on a 1 pipe sort of setup to allow the condensate to drain below the main.

Nick_Castrads

Thanks @mattmia2. Re the column of air issue, I should have said - there's a master vent at the top of that condensate drip. I should've included this photo sooner as it also shows the junction with the steam main coming through the wall. Unfortunately I didn't take a photo from the other side of the wall, but it's the definitely the steam main / riser going up to the rest of the house.

And here's the bottom part of that same riser as it connects to the radiator:

mattmia2

The steam will push the air out of the main through that vent but the air in the riser below it will just sit there because it doesn't have anyplace to go at the bottom of that riser so it will keep the steam from getting to the radiator and causing hammer.

dko

That vent has been a leaking quite a bit!

Steamhead

https://forum.heatinghelp.com/discussion/comment/1806089#Comment_1806089

Yup, and it is probably too small. @Nick_Castrads , how long is that main, and what pipe size? Is it the only main in the building?

Nick_Castrads

@mattmia2 good point about the trapped air. Hadn't thought of that.

@dko well spotted.

@Steamhead that drip line is about 5'6" long top to. bottom and pretty sure it was 2" pipe on the vertical reducing down to a 1-¼" connection at the top left of the radiator.

When you say is it the only main in the building - I'm not sure I've understood properly. This master vent in the photo is at the top of the drip line, at the same level as the horizontal steam main. The boiler is in the center of the home and the steam main extends to both the front and back of the property. This picture / radiator is at the front of the home. I didn't see an equivalent radiator (below the waterline) at the back of the property - just a normal elbow close to the ceiling leading to a riser to feed the upstairs radiators. Please tell me if I've misundertood your question!

Steamhead

@Nick_Castrads , you got it right. There are two steam mains in that system, one going to the front, the other to the back. There should be a vent at the end of each main.

The vent in the pic will need replacing. If we know the distance between the boiler and the vent, and what the pipe size is, we can determine the proper vent to use.

EBEBRATT-Ed

That rad needs to fill with water (condensate) to the boiler water level to get any heat out of it. You may have trapped air in the rad which will reduce its output hence the hot water bleeder on the rad. It will never work as a steam radiator.

Mad Dog_2

I've seen old side arm heaters that used large Diameter pipe where'd you get some natural circulation when the steam boiler ran..Mt father in law Don called it a Salamander side arm heater Mad Dog 🐕

Mad Dog_2

It was basically an Everhot Tank with 2 1/2" or 3" Tappings...Mad Dog 🐕

The Steam Whisperer

I've put several of those in over the last few years. As long as there is a decent amount of condensate draining off the main, the radiator will heat nicely. Remember, condensate flow is about 1/80th of hot water heat flow, but you are running a delta tee across the radiator of about 140F, so it delivers a fair amount of heat even at low flow. They have solved the problem of heating basements now used as living space or those that were getting so cold it was chilling the spaces above.

Nick_Castrads

@Steamhead thanks, that's helpful. I don't know the distance but I can find out. That said, I'm not contracted to do any plumbing (as always) so I'm minded instead to recommend eg John to the client if he'd like the job...

Nick_Castrads

@Mad Dog_2 "Salamander side arm" - love that!