Trane vapor system repairs, updates, and maintenance (vents, re-piping, controls, etc.)

Curious_J

Thank you to everybody who provided input to my previous thread, "Mysteriously missing make-up water" - your help was invaluable to guiding me through the initial stages of confirming the problem, working with the contractors, and identifying additional issues. As a bonus, you taught me some fundamental principles I was shaky on. So, thank you!

A quick update... I am following @Fred's advice, "find a plumber or heating Pro who is willing to work with you and learn, you can manage the installation as it progresses, with the help of the people on this site and you can get it done." (By the way, that is an awesome thing to read... knowing that so many experts have your back is a warming (haha) and confidence instilling feeling.) So, the contractors that looked at the problem agreed that it was a leak in the underground wet return that was responsible for the missing water. I am in the process of getting asbestos removed and a hole cored through a brick chimney so the replacement pipe can go above ground - on the basement floor rather than under it. Once this is done, one of the owners of the mechanical company is going to come out to confirm the plan and draw up a firm estimate. I want to take this opportunity to consider some additional work and I would really appreciate your input.

First, a recap of the system:

• Two-pipe system that I believe is a Trane vapor system
  
• New Yorker CGS-A Series boiler circa 1998 rated at 245k input BTUs
  
• Honewell PA404 additive Pressuretrol (set at near .5 cut-in with an additive 1psi cut-out)
  
• McDonnell probe-type LWCO
  
• McDonnell electric solenoid water feeder
  
• American Radiator Co. tubular radiators with Trane valves and Trane B1 traps
  
• Main vents and return vent I believe to be Trane float vents (confirmation appreciated)
  
• The system heats a 2,900 SF house in southeast Michigan built in 1884
  

Now, a list of repairs, upgrades, etc. under consideration:

• Vents: One main vent is visibly broken, the other is on the shorter of two mains yet the radiators take a long time to heat, and the return vent is loud (which I understand is a sign of failure). Given these facts and the fact that they are all believed to be original and 95+/- years old, I figure they should be replaced. I understand that the only option for a vacuum vent is the Hoffman #76; however, I've seen conversations on here about using a check valve in front of a non-vacuum vent. How about adding a swing check valve (125 WSP, 200 WOP) in front of a B&J Big Mouth? What would you suggest for the return vent?
  
• Vent Location: Currently my vents are directly atop the drips (see pics below). I believe this is how Trane recommended the piping be done (see diagram below); is there a reason why? Is there a way to protect the vents without removing the asbestos on the steam and return mains to tee in a fitting for the vents 15" from the drip as I understand they should be? For example, could I add an elbow to the existing vent tapping and extend a 3/4" piece of black pipe horizontally back xx"?
  
  
  
• Near Boiler Piping: I received several comments on my last thread that my near boiler piping was improper. I looked up the boiler installation manual and I think I understand what needs to be changed except for how the two supply mains branch off. My system has two mains: one that goes north and runs clockwise around the perimeter and one that goes south and runs counter-clockwise. (For reference, the front of the boiler faces south.) I am attaching a couple pics that show the current piping with the north main shaded in blue and the south main shaded in red. How should the two supply mains connect to the header?
  
  
  
  
• Controls: Currently, I have a Pressuretrol that is set to cut in at 1/2psi with a 1psi additive differential. However, I have seen my pressure gauge (which goes to 30psi, so not extremely accurate at low pressure) rise 3psi without shutting down the boiler. Should I assume the Pressuretrol is broken? Regardless, would I be better off with a Vaporstat? If going the Vaporstat route, is a L408J1017 a good choice?
  
• Water Feed: In the previous picture, you can see my current water feed setup. It feeds very slowly and my mechanical contractor says the galvanized pipes are likely narrowing. He also says I can do without the pressure reducer. I think I am going to redo this in copper. Is there any problem tying it into the hot water line rather than cold (my rationale is that it will reduce some mineral and oxygen content and be less of a 'shock' when it hits the hot boiler)? Aside from using ball valves, would you make any other design changes?
  
• Air Separator: Reading all of the posts on here as well as putting hundreds of gallons of make-up water through my boiler in the last couple weeks has me good and paranoid. I was considering an air separator - both Spirovent and Watts looked like contenders. Originally, I was going to plumb this into my water feed, then I thought it might go better in my wet return. Then, I thought it might get gunked up pretty fast in my wet return. Thoughts? Is it worth it? Where should it go?
  

Thank you again for all of your help; I couldn't do it without you!

Jamie Hall

Others will comment on various aspects. I'd just like to make a couple of comments.

Main vents. Ideally, yes, they would be Hoffman 76s. These vents will allow your system -- barring leaks! -- to go well into a vacuum when the burner stops, which will increase the overall efficiency of the system. However... they are expensive. Very expensive. Personally, I am not convinced that the additional expense is compensated for by the additional efficiency. I would use Gorton#2s instead. The BigMouth is a fine vent, but it won't close against water. Some have suggested the check valve idea, which does cut the cost. However, unless you can find a check valve which reliably opens on 1 ounce per square inch differential pressure and equally reliably closes vacuum tight, you will be obliged to run the system at a higher pressure than the Trane system wants, just to get them to open. I have not been able to find such a valve, and I recommend against it.

Vapourstat. The model you mention is the 0 to 4 psi model. You want the L408J1009, which is the 0 to 16 ounce model. For starters, set it at a cutin of 2 ounces and a cutout of 8.

You can use either hot or cold water for the feed. Do redo it in copper -- your plumber is right about the galvanized pipes. Do NOT use softened water, however!

You don't need an air separator. The boiler does that just fine.

Curious_J

@Jamie Hall Can I use the Gorton #2 on the dry return main, as well?

Also, do you have any thoughts about my vents being directly on top of my drips? Is there a way to protect them without removing the asbestos in the main and threading in a tee?

Fred

@Curious_J , in addition to what @Jamie Hall said, your second main will tie into your header just like the one in your first diagram. It should tie in next to the first main. The Header configuration should be Boiler riser, 2nd Boiler Riser, Riser to Main, Riser to 2nd main, equalizer at the end of the Header, after the 2nd Main. Hartford loop should tie into the Equalizer, a couple inches below the Boiler water line.

Jamie Hall

You not only can use a Gorton #2, there, you have to. Maybe two of them. That's where all the radiator air goes to escape the system!

On the vents on the steam main. I have to answer that question with another question: are there crossover traps between the steam mains and the dry returns? These will be a trap -- just like a radiator trap (in fact, they may be identical) -- which is connected to the steam main through a T, nipple, 90 degree to horizontal, nipple and then the trap, then the outlet of the trap straight down (almost always) to the dry return.

If you have crossover traps, then you do not want main vents on the steam main, and shouldn't install any. Furthermore, if there is evidence that there once were crossover traps, such as that location on top of the drip with a corresponding location on the nearby dry return, reinstall crossover traps piped as noted above. Look closely -- removing them is a not uncommon knucklehead trick -- well meaning, but knucklehead nonetheless.

Otherwise, yes, it is easy to protect vents in that location (the traps, if there, wouldn't need protection). Go straight up with a short nipple, then a 90, then horizontal with a inch or so, then a 90 up and a nipple to the vent. Be sure that the horizontal is oriented so that it can't trap condensate.

Curious_J

@Fred Is this correct...

Fred

Yes, that configuration is correct. With a boiler that size and a vapor system at that, , a Drop Header would be great. It produces much dryer steam. Just add another 90 elbow (turned down) right before where the boiler risers ties into the header, then a short, maybe 6 inch nipple, on each of those elbows and then the header. keep in mind the 24" rise, above the boiler water line is a minimum. If you can go higher, do so. All of those things will help make dry steam.

Make sure the risers out of the boiler are full size (no reducers or bushings) and make the Header one size larger than the risers.
You can reduce the size of the equalizer to 1.5" but, if you do, make sure the reducer is on the vertical, not horizontal where it can hold water in the header.

Curious_J

@Jamie Hall There are no crossover traps nor are there any locations at the end of the steam main where the dry return is in close proximity. Would the methodology in "Balancing Steam Systems" be useful here or is that 'overthinking' a simple scenario?

Curious_J

@Fred I have seen pictures of drop headers without knowing what they were or why they were. Thank you for the education! I shouldn't have a problem with the 24" rise, but, for reference, is that 24" at the highest point of the of the boiler risers or the header, itself?

Jamie Hall

The 24 inches is the minimum from the water level in the boiler to the bottom of the header.

I'm sort of surprised there are nor ever were crossovers, but systems vary -- in that case, nice big vents at the ends of the mains are in order. The methodology you mention is good -- but don't overthink it. It's almost impossible to over vent a main.

Fred

Curious_J said:

@Fred I have seen pictures of drop headers without knowing what they were or why they were. Thank you for the education! I shouldn't have a problem with the 24" rise, but, for reference, is that 24" at the highest point of the of the boiler risers or the header, itself?

As Jamie said, on a conventional Header, it is 24" from the boiler normal water line (the water level in the boiler when it is idle).
When doing a drop header, the riser should be a minimum of 24" and then turn down. The header, can then be just a couple inches above the top of the boiler or any level, so long as you stay above the top of the boiler.

Curious_J

I take it that the higher the riser, the better it is to ensure dry steam? Does the length of the turn down have any impact?

Also, the installation diagram calls for the header to be 3". I have one main that is 3" and one that is 4". What are the dynamics of the steam in this scenario? I assume that every time it enters a larger pipe, it slows down? But, isn't a larger pipe also less resistance? Do I have to consider any of this while connecting the header to the mains?

nicholas bonham-carter

The larger pipe will have more air to evacuate, needing more Big Mouth vents. If the back pressure of venting is very low for each, then they will both fill, before the air begins to escape from the radiators, where the resistance is higher. This is where the low pressure gauge shows its worth.—NBC