The only two-pipe radiator in the home.......

KeithDoell

Hello I am a Contractor and I have a Client that has an older home that has a closed in porch where the radiator was pipe in a two-pipe configuration. All of the other radiators are one pipe. I noticed that the radiator in question is different in its style than all others and has a steam vent on the side of it which is not clogged. This radiator also does not have a steam trap connected to it. In my case, this radiator is slow to heat up. Also, the furthest radiator in the Master bedroom also is slow to heat.

I have done all the basic things to get both these radiators to heat better (changing vents, checking shut off valves, insulating pipes, making sure the ph is correct on the boiler, changing main vents, slowing down the vents near the thermostat to get a longer run time.....) but with less than impressive results.

So here is my question, could this two-pipe radiator be negatively impacting the overall system in steam production. This system has a dry return and I did a sizing of the boiler that was replaced seven years ago and using Dan Holohan's pick-up factor of 1.5 I should have had a 135K DOE and they installed a 122K DOE. Since the home owner is new to the home there is no history to how well the new boiler heated.

Any thoughts?? I think at this point the Client is just going to settle for "it is what it is" but I would like to solve the problem if possible.

EdTheHeaterMan

Did I understand that the slow radiators are the furthest from the boiler? Is there a main vent at the end of the main? We need to get the air out of the way as fast as possible. If the radiator vent is the only vent between the place where the fast acting radiators take off of the main, then adding a main vent close to the slow radiators may help.

Jamie Hall

If there really is a dry return for that radiator, is there a vent on that return? That would help.

KeithDoell

Okay, to answer both questions the mains off the boiler go left and right and both return as dry returns. I replaced both the main vents that are on the end coming back.... The two pipe radiator is on the first floor and is a very short run leaving and going back to the boiler since the boiler sits very close to the closed in porch. The other radiator (one piped) is the furthest away on the second floor than all the others (35 foot run approx.)

On the two pipe radiator it is coming back as a dry return.

Jamie Hall

Let's be very careful on nomenclature here -- it's important. For the two pipe radiator, is it possible for steam to get from the steam main to the pipe which you are referring to as a "dry return"? That is, is there any form of trap or such between the steam main and that pipe, or does the steam main just continue through some fittings to the pipe?

If it's the latter, then what you effectively have is a two pipe with air vent system -- for that particular radiator -- and they have different rules. You may get better results with a larger vent on that radiator.

Danny Scully

@Jamie Hall, I beg you to stop with this “steam main extension” crusade you always seem to be on 🙏🤣😉 

KeithDoell

Jamie: From the main, the branch goes through some fittings to the top of the radiator which has a shutoff valve on it. On the far end of the radiator it comes off the bottom and then goes through some fittings to the dry return. There is a typical steam vent on that return end. It has a Heat-Timer Varivalve set at the highest setting.

Jamie Hall

Danny Scully said:

@Jamie Hall, I beg you to stop with this “steam main extension” crusade you always seem to be on 🙏🤣😉 

OK, I will. If, and only if, you can guarantee that no one ever confuses the two and pipes them up wrong again. Since neither one will work properly if you pie it and vent like the other.

In fact, I'd be delighted to have clear nomenclature.

Let's take two steam systems, both operating properly.

System One, Pipe A. Never has steam in it. Operates at atmospheric pressure. Must be vented (or open to atmosphere). If two or more in system, must be connected above the water line. Has return pipes from two pipe radiators (usually, but not always, with traps) connected. May or may not be connected through crossover traps to steam main, but no direct connection.

System Two, Pipe A. May or may not have steam in it, depending on vent location. Operates at steam pressure. May or may not be vented. If two or more in system, must not connect above water line. No return or supply pipes connected. Has direct connection to a steam main.

What do we call these two pipes?

ChrisJ

Jamie Hall said:

@Jamie Hall, I beg you to stop with this “steam main extension” crusade you always seem to be on 🙏🤣😉 

OK, I will. If, and only if, you can guarantee that no one ever confuses the two and pipes them up wrong again. Since neither one will work properly if you pie it and vent like the other. In fact, I'd be delighted to have clear nomenclature. Let's take two steam systems, both operating properly. System One, Pipe A. Never has steam in it. Operates at atmospheric pressure. Must be vented (or open to atmosphere). If two or more in system, must be connected above the water line. Has return pipes from two pipe radiators (usually, but not always, with traps) connected. May or may not be connected through crossover traps to steam main, but no direct connection. System Two, Pipe A. May or may not have steam in it, depending on vent location. Operates at steam pressure. May or may not be vented. If two or more in system, must not connect above water line. No return or supply pipes connected. Has direct connection to a steam main. What do we call these two pipes?

Dry returns.


Call them both dry returns.

Since you cannot guarantee that boilers will be piped and sized correctly even when everyone is given an actual picture.....

I don't think we have much to worry about.


Two pipe dry returns are different than single pipe dry returns.  

ChrisJ

Though it is funny he called it a crusade.

EBEBRATT-Ed

@KeithDoell

This one two pipe rad without a trap could be the issue. If steam gets through that rad with no trap and can make it back into a steam line it could keep other radiators from heating. If it isn't connected to a wet return by itself it may need a loop seal or a trap so as not to upset the rest of the system unless the pressure is really low

KeithDoell

Here is a diagram I drew up of more a less the way it is laid out

Jamie Hall

That's a two pipe air vent setup. Treat it just as you would a one pipe radiator -- the size of the vent will control the heat. Be sure that any other valves are fully open, and that there is good pitch on the pipes from both ends.

KeithDoell

Thanks for all your ideas on this problem.

I am going to send some photos of the radiator that is two-piped so you can get a visual. Also, there is an electric baseboard in this closed-in-porch so it leads me to believe that this radiator never worked correctly (the radiator is 20"H X 70" long with 28 sections and 5 columns). In my mind if this radiator was working correctly, the electric baseboard would have never been necessary.......

KeithDoell

Here are the photos

EdTheHeaterMan

I see you already answered the 2 pipe radiator return is connected A. above the water line. Is the other main's dry return also connected above the water line?

Jamie Hall

At some risk of @Danny Scully getting annoyed again, instead of calling something something I'll ask a question: does the pipe which is labelled "dry return" in the above drawings carry steam at all? That is, does it get steam hot after a while?

How about the pipe from that pipe to the radiator?

And then finally, which sections, if any, of the radiator get steam hot?

if the diagram is correct and complete, you need a bigger vent on that radiator. A MUCH bigger vent. And that may not suffice, as, again, if the diagram is correct and complete, the radiator is being fed from both ends, and the vent will close much too soon to get the air out.

Steamhead

I ran into a similar situation some years ago. Looks like this is similar. Read about it here:

https://heatinghelp.com/systems-help-center/steam-piping-gone-wrong/

EdTheHeaterMan

I am only guessing at the second piping diagram, but if @KeithDoell can double check with a level on the main to the radiators, that would then solve the problem of insufficient heating by the non-original 2 pipe radiator. . A repipe of the return from that rad to below the water line may solve the problem the same way @Steamhead did those many years ago.

@KeithDoell ... when the steam and the condensate are going in the same direction the pitch can be as little as 1" per 20 ft. On a spirit level that is less than half a bubble off of the level center.

KeithDoell

Both horizontal main dry returns (right and left) are connected above the water line.

KeithDoell

Only about less than half of the two pipe radiator gets hot the rest is warm....

Thanks for all your feedback.

Jamie Hall

KeithDoell said:

Both horizontal main dry returns (right and left) are connected above the water line.

Assuming, again, that the diagram is accurate and complete, that's a good part of the problem right there. Can you tell, when the boiler has been running for a while, at what point along the various pipes they get cooler? It's possible that that radiator may be on a section of piping which is starved of steam.

Danny Scully

@KeithDoell, the supply and return cannot connect to the same pipe, at least in the manner that it currently appears to be. This needs to be repiped, possibly with a loop seal to the bottom of the steam main. Make sense? 

EBEBRATT-Ed

@KeithDoell

I agree with @Danny Scully .

You can tinker with the venting and maybe get it to work,

But the sure fix is to disconnect the return and drop to the floor with a loop seal and then go back up into the return pipe.

You have steam coming in the return possibly closing the vent then the rad is air bound

KeithDoell

Ed and others:

First I would like to say to all Happy New Year! Secondly, I have attached a drawing on how I would pipe in a "Loop Seal" for the radiator that is two pipe. The original dry return connection point, as view in the boiler room photo (sent in previous comment), is where I would break the connection and then go down below the water line and back into the dry return tee. Any comments on my design would be helpful since it would be the first time I am piping in a Loop Seal.

Thanks

Keith.

Jamie Hall

Wonderful. Assuming that the initial system drawings are correct, and that there is a direct connection between the end of the steam main and the pipe labelled "dry return" -- I won't belabour the point, @Danny Scully -- you are engaged in an exercise in futility. It won'/t make any difference at all where you hook up that return. The loop seal, however, will prevent steam from getting to the pipe.

Danny Scully

@KeithDoell, your sketch is perfect. 

KeithDoell

One last question, should I put some water in the loop seal before I close it with a black union on the vertical or just let the steam condensate fill it up gradually?

EBEBRATT-Ed

It will fill on it's own quickly but like the people who insist on putting water in a steam pigtail under a pressure control you can add water if you want

Danny Scully

KeithDoell said:

One last question, should I put some water in the loop seal before I close it with a black union on the vertical or just let the steam condensate fill it up gradually?

You may as well fill it with water so your initial test yields accurate results. 

KeithDoell

Thanks to all. I will let you all know how it goes.

Have a great week

Best regards

Keith.

KeithDoell

Hello Everyone, I had an opportunity to install the Loop-Seal this past week on the two-pipe radiator and presto it worked! The radiator almost instantly got hot to the touch in seconds all the way across after so many years..... The Client was elated ;-)

A big shout out to all that help.

Best regards,

Keith.