Main/return Venting question

ddanman

I have a two-pipe gravity steam system which appears to be working fine.  Pressuretrol settings under 2 psi and have never had any problems with pressure as I have read on countless threads.  My standard 30psi gauge never seems to raise above 0psi, and It leads me to believe I may have a venting issue.  After reading multiple threads, as best as I can tell there are no main vents, and only one Hoffman #75 on a combined dry return line I found near the boiler - no vents attached to the radiators.  As the boiler heats up, the Hoffman vent starts hissing as pressure builds, and will continue to hiss through the heating cycles and several minutes after the boiler has shutoff after the heating cycle.  My question is whether this is normal operating functions, or am I wasting fuel by not venting the air quicker or the vent not closing during heating cycle?  I believe a normal heating cycle for my system is about 1 hour for 2-3 degrees.  Should it be quicker than that?

Rod

Where are the traps

Hi-  Need to ask you about traps. How many steam mains do you have? Is there a trap on the end of each of your steam main or do they  drop into the wet return? Are there traps on the exit pipe of each radiator? What is the condition of these traps?

- Rod

ddanman

Tane Traps

From what I can tell, I have 3 steam mains, and one return.  I am new to this forum, but have located 3 Trane B1 traps and I am in the process of replacing the insides of all 3 traps with  Barnes & Jones cage unit 4320.  I don't believe they have ever been replaced and I assume they are not working (failed open).  One of the traps is located on the main floor, the other two are located in two of the four bedrooms on the second floor.  I believe these traps are located at the end of each steam main, but I am guessing here.  All the other radiators have what appear to be manual orifice elbows attached to the lower side of the radiator (I can open and close them manually with a key).  All the rooms heat evenly (after adjusting the intake valves) and all the manual returns are opened all the way.  I don't know if I completely understand the difference between the wet return and dry return, but I do have 4 pipes(above the boiler water line) that all connect to the common lower water return pipe (below the boiler water line) that connects to the boiler.  The last 2 pipes in the chain (3rd, and 4th) are not insulated and appears to be the common dry return with the 4th pipe having an isolated 20ft non-insulated loop up near the ceiling with the Hoffman #75 hooked close to the other adjoining pipes and connects at the base near the bottom of the previously mentioned 3rd pipe.  I'd be happy to attach an image later if it would help.  I am happy with all the heating except for one bedroom, which does not seem to fully warm up/stay warm, even though the radiator heats up completely and has a fully open intake valve.  I am hoping replacing the traps will fix this issue (Trane trap is NOT located in this trouble bedroom).

Rod

Traps

 Dry return/wet return- This confused me for a while. Basically what it means is that return pipes above the waterline are dry return and those below the boiler water line are wet returns. If the pipe is vertical it is considered a dry return above the boiler waterline and a wet return below the boiler waterline even though it is the same pipe! Being below the boiler waterline and attached to the boiler the wet returns normally contain water (condensate).

I find it helps to think of your system as a ladder. The right side of the ladder is the steam main and the left side of the ladder is the return. The radiators are located on the rungs.

If the boiler is located at the bottom of the ladder, the end of the steam main is the right side of the ladder at the top and if the right side of the ladder doesn't drop into a wet return, it then has to be connected to the top of the left side of the ladder with a trap in between.

This trap allows for the venting of air from the steam main and the return of condensate to the boiler. The air continues down the dry return and out the vent on the dry return.  The condensate continues down the dry return and drops into the wet return. Cleaning and rebuilding these traps should help quite a bit. It sounds as though you have everything under control and things are working quite well. You might want to add some more venting in addition to the Hoffman 75.  Do you have orifices on your radiator inlets? You might want to check the inlet and outlet of the "bad" radiator to see if any dirt etc. is blocking it slightly.

- Rod

ddanman

2 mains

I had a chance to take a closer look and take a few pictures.  I actually only have two mains - shown in picture.



"A" main feeds East side of house (both floors).

 - 4 radiators on main floor east side, no traps.

 - 3 radiators on second floor east side, 1 trap on first rung.



"B" main feeds West side of house (both floors).

 - 2 radiators on main floor west side, 1 trap on first rung.

 - 2 radiators on second floor west side, 1 trap on first rung. (2nd radiator has the issue)



"C" return is combined condensate returns from all radiators.



"Loop" unclear how or why this is here except it has the only vent (Hoffman #75a) attached to it.



Is there a reason why not all the radiators have traps?  I think that would be best.  The boiler was replaced in 1991, and I have a feeling they did not quite know what they were doing has they replaced part of the mains with copper as seen in pictures.  I think they also removed vents in the main returns as there are some capped off smaller sections above the returns in the second picture.



As for your question, I have removed a few radiators around the house to refinish the floors or paint behind, and have not found any inlet orifices, including the trouble radiator.

Rod

Piping

I looked at your pictures and you have some serious problems with the configuration of your near boiler piping. It isn't very efficient as it is now. Do you have the Installation manual? If not, let us know the model # of your boiler and we can try to find it for you. If you have the manual, find the page on piping the boiler and compare it to what you have now. It should also be piped in black pipe rather than copper.

All the pipes dropping down to the wet return - marked in the picture "A" return,"B" return,"C" return and "Loop" are all returns   At the top of each of "A" return, "B" return, and "C" return, where the pipes start downward, there are pipe stubs where a main vent would normally go. (The "Loop" already has a main vent)   Take some picture of the exit elbows on the radiator so we have a better idea s to what you have. Where are you located?  See if you can find what the odd return drains. From what I can see in the second picture there seems to be a open disconnected pipe up in the returns, Any idea where this runs to?

- Rod

ddanman

Follow up to your questions

Attached are what I call the manual return orifices?  I don't really believe they are traps of any kind.  All of the 8 other radiators have these same returns.  only 3 have Trane B1 traps.  As for piping, I can look for the manual, but the system is a "Weil-Mclain steam boiler –  EG-55 STEAM PID". 

The open pipe in the picture is an abandoned gas pipe and is not connected to the system in any way.  The loop attaches at the top of the "C" return loops down to the end of the house (20ft) and back and attaches near the bottom of the "C" return in the picture.

Steamhead

That's a "Moline Heat" system!

No one else used those lock-shield valves on the returns.



This system originally had a steam-powered ejector that pulled air from the mains and rads, and a vacuum check to keep the air out. This was installed at a central point in the dry return network, and included a condensing pipe loop or radiator piped after the ejector. The "loop" you mention may be the condenser or it may have supplied the ejector with steam. I think I see the ejector at the upper right of the second pic- it's a tee with a bulge in it that feeds into a pipe which quickly increases in diameter.



The steam valves on the rads had built-in orificing capability. The valves on the returns were shutoffs- they did not serve to keep steam out of the returns.



The rads with the Trane traps may have been installed later.



Where are you located?

ddanman

You guessed it!

Moline, IL.  I am the proud owner of over a 100 year old Crasftman style 4-square.  From the "Find a Contractor" link, the closest help is in Chicago (3 hours away).  I would really like to know more about what this system was, and what it is now, and what I can do to make it more efficient.

Rod

Vapor Systems.

I'm glad Steamhead saw this thread as he is a very experienced steam pro who's an expert on vapor systems such as yours.  You're fortunate to have a vapor system as they were the ultimate of the steam heating systems. When you get it running properly and tuned up, it will be very comfortable, quiet and economical..

- Rod  - an envious owner of a crude 1 pipe steam system.

ddanman

What's next

I read a lot of the threads on "Moline" vapor systems.  It appears most of the vacuum components have been removed from my system.  About half of my "Moline" radiator inlet valves have been replaced with standard valves, so I will probably order some orifice inserts to fix these.  Should I still go ahead and replace the insides of the 3 Trane traps?  The location and condition of the 3 radiators leads me to believe that someone was trying to fix a heating problem, and replaced the original Moline valves with Trane traps.  What about additional vents on the mains?  And is there anyone in my area interested in re-piping my copper conundrum?  By the looks of it, I could pay you in copper!

Jamie Hall

Couple of thoughts

First, that Hoffman 75 is probably a little undersized -- a bigger vent in that location would help make things faster.  You don't need vents on the radiators.  It is uncertain from your description, but it sounds as though the Trane traps may be crossover traps, which allow air to go from the steam mains to the dry returns.  From which it goes back to the Hoffman.  There is no harm to replacing them, but it is quite possible that they are still working OK; the question is, does steam get by them?  If it does, the dry return would get hot -- steam hot.  While there is no harm to replacing the innards... if it ain't broke, why fix it?



A 30 psi gauge will hardly move on a residential system which is operating properly; it may not even move at all.  You need it for code, though.



If there is a room which stays cold or gets cold despite the radiator being hot all the way across, you need either to find out where the heat is going from that room (bad insulation, No insulation?  Leaky window? ??) and fix that -- or put in a bigger radiator.  Replacing the traps isn't going to help -- if the radiator is hot, it's hot, and that's all she's going to be able to do!



Your cycle time for a 2 to 3 degree set back doesn't seem excessive to me, at least.

Steamhead

Get in touch with

Dave "Boilerpro" Bunnell. He's in Amboy, not far from you, and knows his Molines. Go here for his info:



http://www.heatinghelp.com/professional/105/Boiler-Professionals-Inc

Steamhead

You might just

take the elements out of those traps. Once the system is in tune, they won't be needed.

ddanman

Better than before - follow up question on vacuum

I went ahead and replaced the insides of the 3 traps and the hissing from the Hoffman main vent was practically eliminated!!  Just a quite hush now.  I am also trying to get a hold of Dave the "BoilerPro" for assistance with questionable piping issue on my Moline Vapor System.  I read the article in the library about the system and I have a question about the vacuum part of the system.  I know the vacuum valve on my system was replaced by the Hoffman, and I have read other threads that state that the vacuum part is no longer necessary on newer oil/gas boilers, but my question is from the literature, the vacuum part keeps the steam in the pipes and radiators longer than a typical "open air" steam system... Wouldn't that still apply today?  I would like to trap the heat in the radiators as long as I can, keeping the rooms heated longer, rather than letting the air rush back in through the Hoffman.