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Steam boiler zoning

Kirby83 Member Posts: 5
edited December 2020 in Strictly Steam
Bought a place with a new boiler 2 years old. There have been constant complaints about water hammering from the occupants.  It’s a 1 piped system that has zone valves for each unit.  I am going to try and lock valves open and install 1 thermostat for the boiler to run from.  It didn't make sense that the zoning was in place and could support running the boiler with multiple closed valves.  Looks like zoning was put in at some point over the years but not original to home in 1924.  The main line air vents were also leaking.  Does trying to remove the zoning make sense to do?  Thanks for the help


  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Zoning a steam system -- either one pipe or two -- can, in principle, be done. To do it in a way which ensures that water hammer and condensate return problems do not occur is very difficult, and requires real expertise to accomplish. It's not just a matter of sticking a valve in the runouts or mains.

    If you are really fortunate, the valves are full port types and you will just be able to lock them open. If they are not, just locking them open probably will not get rid of the water hammer problems, and they may need to be removed.

    Once the radiators are balanced (replace the main venting first, if it has failed -- and find out why they failed; most likely excess pressure) then if certain apartments are too warm, you can put Temperature Regulating Vents on the radiators which are too hot. Make sure the radiator valves are fully open and stay that way -- you may have to remover the handles to discourage do it yourself tenants.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • AMservices
    AMservices Member Posts: 610
    I would recommend using a tekmar 279 
    It will control the boiler based on outdoor temperature. 

    Install TRV air vents so every radiator can be its own zone. 

    Then correct near boiler piping so there boiler is producing dry steam. 
    Look over all the piping. Make sure all the radiator valves are tight and not leaking. 
    Pay special attention to how all the air is getting out and how all the condensate returns. 
  • Kirby83
    Kirby83 Member Posts: 5
    edited December 2020
    Thanks for the info. I think the Hoffman #45 may be too small and couldn’t handle the pressure. I replaced them a couple of months ago just using what was there and think it’s time to go with a different one. Does Gorton #1 make sense? I have 4 to replace. Old photo attached. I also took one of the zone valves that I plan on opening tomorrow and new thermostat.  Also added picture of piping.  I checked the manual and couldn’t find any diagrams of the dual supply line to compare against what they did but it looks incorrect?  Thanks again for all the help 
  • Kirby83
    Kirby83 Member Posts: 5

  • Kirby83
    Kirby83 Member Posts: 5
    Thanks for the advice! I was able to get the valves locked open and put a main temporary thermostat to run the system.  2 main vents were replaced with Hoffman #45s that I cleaned up and had on hand for the time being.  I’m wondering if they are still too small though.   Water level normalized in the boiler and water hammer and knocking has completely stopped.  Had a service call today for newer tenant with heat complaint.  Radiator valves were partially closed and I adjusted venting.  Gonna check out TRVs and new thermostat now.  Wouldn’t have been able to get this figured out without this site!  Beats the system replacement that was recommended by pretty reputable local company(boiler is 2 years old). You folks are awesome.  
  • motoguy128
    motoguy128 Member Posts: 393
    Could put big mouths on the mains.  But I would install a strainer and a 12” pipe nipple to keep water/debris  out.  
  • dopey27177
    dopey27177 Member Posts: 887
    zoning any steam system requires a condensate pump and a T stat for each zone or sufficient height for condensate to over come the the steam pressure in the boiler.

    See the enclosure

  • ChrisJ
    ChrisJ Member Posts: 15,706
    That piping by the boiler is going to hammer no matter what you do.

    Unfortunately it needs to be completely redone.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment