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Clogged return?

I was called to a house by a contractor to replace 2 free standing steam radiators with sunrads in order to gain space within the room. No complications and the install went well. While I was there the customer indicated that they have 3 radiators in an 2nd floor area above an unheated heated garage that dont get hot consistently and the rooms up there are generally cold. These rooms are by far the furthest from the boiler She also indicated that a few rooms throughout the house over heat and the general state of the system is not balanced.
The house is 80+ years old. The system is a single pipe with wet returns. The system has three 2" mains. Someone replaced the original boiler probably at least 30 years ago. There is no header, equalizer or hartford loop! Main #1 is approx 20 feet long and is supplying only 2 radiators. Main #2 is only about 15 feet long and supplies 3 radiators. Main #3 is 40 feet long or more and supplies 7 radiators. The second floor rooms that are cold are supplied off main #3. Main #3 is fed directly off one of the tappings on the top of the boiler. Mains # 1 and 2 are split off a 2" tee at the ceiling above the boiler and that tee is fed by the second tapping off the top of the boiler. I raised these issues and my concerns to the customer and she said that for the most part the house was overall comfortable, No banging and other then a few balance issues worked well.
As I started to inspect the system further I noticed no vent on the end of main #1. The vent on the end of main #3 was spitting rusty water.None of the mains are insulated.
I started by adding a vent on main #1 and replacing the vent on main #3. I then replace all radiator vents with adjustable ones. I also lowered the pressuretrol setting to about a pound or less. After firing things up from a cold start I was able to trace the steam and got everything to heat pretty evenly both on the first and second floors as well as delaying the one or two rads that were overheating and getting the 3 that are above the garage good and hot. I left feeling that we made some really good progress and explained to the customer that do to the fact the the weather here in NY is still inconsistently warm or cold that it may take a cold snap in order for the system to run steadily for a couple of days in order to show the full affects of the balancing.
Well, after a cold snap this weekend the customer called and said that the system was banging (not sure from where yet as I have not been back there) and that a large amount of rusty water is spewing from the air vent on the 2nd floor radiator farthest from the boiler that is in the room above the garage. Remember that when I got there the vent on the end of main #3 was spitting rusty water and this radiator is fed near the end of main#3.
The boiler is not overfilling (there is an auto feed) so I do not think the return is clogged. What could be pushing the water up that high and far? How come none of the other rads that are closer to the boiler and main aren't getting the water first? Could just this radiator pipe be restricted or clogged? Or should I be looking deeper? I know the near boiler piping is not right but for 30 years the house has not had any major issues. Why now when the only significant change is that I have the room above the garage getting warm when before it was not. Too much steam too quickly? I'm going back there this week and want to be armed with some knowledge as to what to look for.


  • ethicalpaul
    ethicalpaul Member Posts: 4,666
    With no header, no equalizer and assumedly weird near boiler piping, it’s very easy for water to get thrown up into the main and farther.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • Jamie Hall
    Jamie Hall Member Posts: 21,111
    and with that one main being fed directly off a tapping on the boiler, now that you are getting steam to move decently I wouldn't be all that surprised that you are getting water into it. Does that main have a wet return at the end of it? Which way is it pitched?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 10,579
    And always the question of the steam pressure, pigtail clean and control adjusted as low as possible.
  • Fred
    Fred Member Posts: 8,541
    Is That 2" main adequate to support 7 radiators? What is the total EDR of those 7 radiators?
  • joe amadio
    joe amadio Member Posts: 41
    So I am not concerned with the EDR of the 7 rads being supplied off the 2" main because a deadman did that calculation when the house was built. As I mentioned previously the pressuretrole is adjusted as low as possible. And yes that main has a wet return and the main itself is pitched away from the boiler. What about some "Dry steam" additive to prevent the water from being thrown up into the main?
  • Fred
    Fred Member Posts: 8,541
    Did that deadman factor in that someone would install a replacement boiler with no header or equalizer? With the possibility of additional water being thrown up into that main, it is possible the capacity to handle steam and condensate/water just isn't there.
  • joe amadio
    joe amadio Member Posts: 41
    So then the answer is build the proper header correct?
  • mikeg2015
    mikeg2015 Member Posts: 1,187
    The 3rd main requires 2x the steam flow and it’s located the lowest off the boiler if I read it correctly. Balancing it increased the steam flow to that main so now it’s getting a lot of wet steam or even water right out of the boiler.

    Also, lowering the pressure probably made it worse. Now that it heats more radiator surface initially, pressure is lower so velocity is higher.

    What’s the A dimension to the lowest main?

    Even the most minimal header and equalizer will probably fix it. Hartford is a good idea too.

    Customer may not want to pay for a full day labor and materials however.

    Did you skim after replacing radiators?

    For now you could slow vent to garage and maybe everything so it builds more pressure.

    The rusty main vent was a symptom.
  • Fred
    Fred Member Posts: 8,541

    So then the answer is build the proper header correct?

    We haven't seen any pictures of the set up so we are shooting in the dark. Besides, there are no guarantees but it certainly would go a long way towards eliminating the possibility.