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A few steam system questions

Mike_Sheppard
Mike_Sheppard Member Posts: 680
Got a building in DC having some steam issues. Four stories with a basement.

Boiler is shut down for the season. Two pipe gravity return system. No condensate tanks, all returns to the boiler with a buried wet return. No boiler return traps either. Boiler is in the basement about 10 feet below the lowest radiator. Should be plenty of A demension. Running on a 0-16oz vaporstat. Automatic feeder is constantly feeding which tells me the buried wet return is leaking, no water on the ground anywhere in the boiler room. Boiler was replaced last year (likely due to leaking wet returns) How do you guys go about finding and repairing a leak on the wet returns? Is it best to just dig up the whole thing and replace it? I’m assuming that is the best option. The shape the pipe probably is in I’m sure it all needs to be replaced.

These radiators don’t have thermostatic traps, they have the elbows with balls checks in them. Wasn’t there a specific name for this kind of system? I’ve seen it posted a few times on the forums I’m pretty sure it’s on the website.

Can the elbows be replaced by thermostatic traps?

The customer wanted me to come to shut the boiler down. But it has a Tekmar control so it shuts itself down. That’s when I noticed the feeder feeding. I started talking to him about that and he mentioned the “crazy water hammer” the building has been having for years now. I told him about the elbows and needing to check over the entire system, and repairing the wet returns. I got the usual response about not having the money to pay for it. He said they’ll have to live with it. I will try my best to talk him in to making the fixes. It’s tough explaining that spending the money will save money...

Oh and the header is piped wrong. I’m sure that isn’t helping the water hammer... the two take offs are between the risers from the boiler... There are two risers from the boiler and the header is the same size as a single riser. When the boiler was replaced the old header was used.
Never stop learning.

Comments

  • Mike_Sheppard
    Mike_Sheppard Member Posts: 680
    I think I meant to say B dimension not A dimension since the returns aren’t pressurized.

    I’m going to attach a picture of this elbow. Does this elbow look like it would have a ball in it or is it just an elbow?
    Never stop learning.
  • clammy
    clammy Member Posts: 2,665
    The 2 ways it goes is reroute them as low as possible and if need be install a false water line to keep that wet return seal or dig up the old ones and replace them possible install plastic drainage trenches instead of reburying them .There s no sense in my book to peice meal buried wet returns cause by the time there finally all replaced the boiler is either toast or needs to be flushed out from crud build up .Just a suggestion install ball valves and drain tee s on all drops it makes it easy to flush them out later .I would first check the boiler and have a very good look about peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    If indeed there are little balls in what looks like a return elbow, it may be a Richardson. Or, more accurately, it may have been a Richardson once upon a time...

    If indeed it is, the pressure needs to stay low. Richardson quoted 5 ounces; you might get away with 6 -- but any much more than that will get by those elbows.

    Each dry return should be vented just before it turns down to the wet return or the boiler. Steam mains don't really need to be vented, though it won't hurt. They DO need to be insulated, though.

    I'd go after the usual suspects for water hammer first -- bad pipe pitch. But I suspect that the poor header arrangement is doing the system no favours.

    On the wet return. @clammy 's pretty well got it. Just make sure it really is wet and stays that way.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JUGHNE
    JUGHNE Member Posts: 8,924
    What do the supply valves on the radiators look like.....picture.
  • ratio
    ratio Member Posts: 2,918
    WRT finding a leak in a buried return, I used a Fluke VT04 with good results. You might want to be there for a cold start, so the floor isn't too warm already, but the leak was obvious—a round hot spot on the floor. I think any of the new cheap (& not-so-cheap) thermal imaging accessories for smart phones would work too.

    Or bring a cat.

  • Mike_Sheppard
    Mike_Sheppard Member Posts: 680
    edited April 2018
    @JUGHNE sorry I didn’t snap a picture of the supply valve. I knew I should have. I will attach a picture from some Richardson system literature to show you what it looked like. It didn’t look EXACTLY like this but it was very similar. Same style handle.

    @Jamie Hall I think you’re right. After reviewing some Richardson literature this is exactly what the elbows looked like. They are probably original... it would make sense though that these could be converted to thermostatic traps right? Although I see how the inside of the nipple dips down into the water in the bottom of the radiator, I’m wondering if water would pool down there if that nipple/elbow were removed. Each dry return has an air vent. Hoffman 75s. Probably not the correct air vents.

    @ratio I actually own a Flir E6 that has been working WONDERFULLY this heating season. Have found many leaks though the ground and walls. It has more than paid for itself. My coworkers keep wanting to borrow it to find leaks with... But I think @clammy is right. The whole wet return should be replaced and protected. Unless they want to be digging up the floor every year. It would be pointless to do just a section of it.
    Never stop learning.
  • Mike_Sheppard
    Mike_Sheppard Member Posts: 680
    edited April 2018
    So here’s a page about the Richardson system from the Lost Art book. There’s a water seal in the radiator to stop vapor from escaping the radiator into the returns, but there’s also a ball there to prevent vapor from coming backwards from the returns and into the radiator. I thought the ball acted as a trap to keep steam from passing but it’s to keep steam from entering.

    So there is NOT supposed to be vapor in the returns correct?

    Even at 5 ounces that would still be enough to blow that water seal out right? Which I’m assuming is why they used those graduated supply valves which kind of acted as orifices to only feed the radiator as much as it could condense, preventing pressure build up in the radiator allowing the water seal to act as the trap. The valve would have to be set to the size of the radiator and not adjusted.

    Does this sound right?

    Edit: can the graduated valves and the ball-check elbows be replaced by standard valves (or TRVs) and regular thermostatic traps?
    Never stop learning.
  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    Does this sound right?

    Edit: can the graduated valves and the ball-check elbows be replaced by standard valves (or TRVs) and regular thermostatic traps?


    Yes and yes. But try the system running on very low pressure first. The combination of a valve (or orifice) which is sized for the radiator, plus that Richardson return, makes for a system with essentially no moving parts to wear out, break, fail, or otherwise annoy you. There's something to be said for that...

    If you can't find replacements for the inlet valves (or some of them have already been replaced) remember that for two pipe steam -- and especially vapour -- there's no rule that says that you can't partly close the supply valve. Of course, if this is a tenant occupied structure (sounds almost like?) you may want to take the handles off -- or tighten the packing nuts so far that they are impossible to turn... or both... to keep busy fingers off.

    Or you could size orifices and figure out how to put them in...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Mike_Sheppard
    Mike_Sheppard Member Posts: 680
    @Jamie Hall the guy there told me many of those valves have been replaced. He said some elbows had been replaced by thermostatic traps, and some elbows had been replaced with just standard elbows because people didn’t know what they were.

    It is a co-op. Not sure how many apartments but it’s 4 stories. I’d guess around 20 apartments.

    I think traps and valves might be a better idea in this situation.

    But that brings up another possible concern. This is a sectional boiler, brand new Smith. Gravity return with no feedwater or condensate tanks.

    If thermostatic traps are put in, could that potentially hold water back long enough to cause the feeder to come on, eventually flooding the boiler when the condensate returns?
    Never stop learning.
  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    Co-op? 20 apartments? Traps and valves! You're going to have fiddle fingers in there, and you need to keep them from upsetting things! As much as you can, anyway...

    Traps shouldn't hold back a significant amount of condensate -- at least not enough to cause a problem. Shouldn't. However, if you find you have a problem later, you can put a tank on the cold return which still operates entirely by gravity -- equalize it with a takeoff from the steam main -- to give you more effective water capacity in the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Mike_Sheppard
    Mike_Sheppard Member Posts: 680
    @Jamie Hall ahhh I like that idea. Thank you a ton for the advice and knowledge.

    I’m going to write up some stuff for this guy and see if I can entice him to make some changes!
    Never stop learning.