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2 zones, 2 pumps. 2 flow control valves?

delcrossv
delcrossv Member Posts: 742
Looking at an old school hydronic system- one pump per zone, no zone valves. Am I correct that each leg needs its own flow control valve so one zone won't be pulling from the other? Or am I overthinking this.

At present there's one valve on the send (pumping toward at present) with tees to the two "zones" afterward.
Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,271
    They don't need zone valves -- but they may well need balancing valves, to ensure that the each zone gets the water it needs.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Henry
  • dko
    dko Member Posts: 586
    I think he's talking about flo-cheks(taco), flow check valve(watts), flow control valve(b&g). not balancing valves.
    delcrossv
  • delcrossv
    delcrossv Member Posts: 742
    dko said:

    I think he's talking about flo-cheks(taco), flow check valve(watts), flow control valve(b&g). not balancing valves.

    Correct.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    There are two reasons for Flow Control Valves
    1. On a tankless coil for DHW boiler you do not want gravity flow from the boiler that is maintaining a minimum temperature. the Flow Control/ FloChek. or IFC check valve in the pump (if it is on the supply) will keep that from happening;
    2. To keep a zone circulator from drawing water backwards thru the piping of a zone that is not operational.

    Look in this book called Pumping Away starting on page 9. The illustrations and text are really easy to follow.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    delcrossvIntplm.
  • delcrossv
    delcrossv Member Posts: 742
    edited March 13
    2. To keep a zone circulator from drawing water backwards thru the piping of a zone that is not operational. Look in this book called Pumping Away starting on page 9. The illustrations and text are really easy to follow.
    This . So, one on each zone?

    Wondering why there was only one with the present  "pumping toward" arrangement?
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • hot_rod
    hot_rod Member Posts: 22,105
    Maybe a sketch of what you have.

    Two pumps on the boiler return, one flo-check at the supply from the boiler?

    There are different names and devices for preventing flow from a circ when it is not running. Some are brand specific names as @dko noted
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    delcrossv
  • delcrossv
    delcrossv Member Posts: 742
    edited March 14
    @hot_rod Here's what's there. Except to prevent gravity flow, I don't get why only one flow control. Each circulator can get some flow into the "off" zone. 
    Is it too little to matter?


    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • delcrossv
    delcrossv Member Posts: 742
    As I understand it, pumping  away would have two valves, one per pump.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    What is the possibility that there was one Flo Check on the original one zone system because it had a tankless coil? Not necessarily the boiler that is there now, but maybe a previous boiler. Then there was a second zone added later in the home's lifetime. But the installer of the second zone didn't get it quite right.

    And since the installer got lucky and just by happenstance the two zones were matched close enough that both thermostats would call for heat regularly, so the homeowner never noticed they had a problem. Or if they did, then never did anything about it because “that is just the way it works” Said a unknowing plumber.


    I really like to look at old buildings thru the eyes of the heating system and try to see how many heating systems may have been in that old home. Old gravity Cast radiators, with 2" mains that left the boiler room, connected with bushings to 1-1/4" iron pipes that reduce to 1" copper tell me that there were at least 3 different boilers in that home. Then the first one may have been coal that was converted to oil... so that makes 4 different systems if you count the coal to oil conversion as 2 separate heating systems in one boiler.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    delcrossv
  • hot_rod
    hot_rod Member Posts: 22,105
    There are any number of ways to upgrade 
    Id bring it into the 2020s with zone valves and an ECM
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • delcrossv
    delcrossv Member Posts: 742
    edited March 14
    @EdTheHeaterMan Nope. One owner, all original equipment since 1956. Supposedly the original Series 100 pumps were replaced with the same model in the 90's Never had a tankless coil.
    Nicest Crane Sunnyday I've ever seen.

    System works, but I don't understand the "why" of it, unless everything gets a little warm even if the associated pump is off.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • delcrossv
    delcrossv Member Posts: 742
    edited March 14
    hot_rod said:

    There are any number of ways to upgrade 
    Id bring it into the 2020s with zone valves and an ECM

    All true, but beside the point (as it ain't broke). Why the one Flo control instead of two? Pumping away using two valves make sense as each circuit is isolated when the associated pump is off. I'm missing something in the logic as to how they got away with a single valve.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    Agree with @delcrossv. It should have a reverse flow problem.

    Since the pump will move the water to the path of least resistance, somehow the resistance thru the boiler and flow control valve, and the path thru the opposite zone that is off, were fairly close. So close that perhaps the amount of flow that would happen by gravity to the non calling zone when the flow valve opened, was equal to the reverse flow of the calling zone’s circulator. If someone replaced one of those B&G 100 pumps with a Taco 007, that balance would be different and who knows what would happen.

    By all other scenarios that should not work so well.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    delcrossv
  • delcrossv
    delcrossv Member Posts: 742
    So ,based on @EdTheHeaterMan 's comment. any configuration change should include a second flow control valve, yes?
    This one was a head scratcher for sure.
    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    Yes. You would definitely need 2 flow control valves of some type. You could use this detailed diagram from an earlier comment, or the one next to it. What ever is easier to configure based on existing conditions. Just be sure to pump away from the expansion tank.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    delcrossv
  • Sylvain
    Sylvain Member Posts: 115
    have a look at this discussion:
    https://forum.heatinghelp.com/discussion/196513/