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zone valve question

Wayco WayneWayco Wayne Member Posts: 2,469
We are installing a large (for us) boiler system of 1.2 million btu's. We have 6 zones of varying sizes. I usually use Caleffi Zone valves but their largest zone valve is 1-1/4" with a cv of 7.5. My biggest zone is 2." Should I reduce down to the zone valve or find another manufacturer that makes 2" zone valves? What problems could I be facing?


  • IronmanIronman Member Posts: 3,525
    CV Rating

    You need to size it by the cv rating, not the pipe size. That, of course, means you need to know the flow requirements for each zone.

    Belimo makes larger size zv's.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • hot rodhot rod Member Posts: 7,059

    Pumps instead of valves. If that 2" zone is 35- 40 gpm that may be an expensive zone valve. Probably not a spring return type thus more complicated wiring. See what every zone flow rate is. I agree Belimo is a good source for high flow zoning valves
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Wayco WayneWayco Wayne Member Posts: 2,469
    What if

    I used two 1-1/4 zone valves and teed them together downstream?
  • SWEISWEI Member Posts: 7,356
    What is the capacity

    of the zone?  How many GPM at what ∆T will answer the question.

    Any reason not to use a pump as Bob suggested?

    Is the main circulator fixed speed?  Is it being replaced?
  • Wayco WayneWayco Wayne Member Posts: 2,469
    I was

    Planning on using a Wilo Stratos 2x3 x35 on six zones. the largest needing 35 to 40 gpm.
  • SWEISWEI Member Posts: 7,356
    why not

    a few smaller Stratos pumps?  How many zone valves are there?  You can run a Stratos ∆T if you need to.
  • Wayco WayneWayco Wayne Member Posts: 2,469
    6 zone valves

    Ranging from 1" to 2 " Why break it up into multiple circs. One oughta work. Or am I missing something? BTW I found Belimo had the 2" zone valve I needed. Thatnks for the suggestions.
  • SWEISWEI Member Posts: 7,356
    edited May 2013
    how many GPM?

    really is the question.  Belimo makes good stuff -- I greatly prefer their CCVs over zone valves.

    What you are likely missing is the opportunity to tune the flow for each zone independently, which would be trivial using separate ECM pumps.  Adding circuit setters or proportionally-controlled CCVs would probably cost more at those flow rates.
  • Wayco WayneWayco Wayne Member Posts: 2,469

    What are CCV's?  My gpm's are; 40, 15, 8, 8, 5, and 5.
  • SWEISWEI Member Posts: 7,356
    edited May 2013
    CCV = Characterized Control Valve

    Basically a ball valve with a special characterization disc which produces linear flow rates based on position.  The first two pages of describe the concept quite well.

    Without knowing loop heads, I'd probably spec a single Stratos for the 40 GPM loop and another for the 15 GPM loop.  I'd set those for the most ∆T I could tolerate on those loops at full load.  The 8,8,5, and 5 loops might get individual small pumps (Bumble Bees most likely) or be combined into one or two groups on a ∆P circ with zone valves.
  • Dan HolohanDan Holohan Moderator Posts: 11,877

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  • Wayco WayneWayco Wayne Member Posts: 2,469
    Still need an answer. why circs instead of zone valves

  • SWEISWEI Member Posts: 7,356
    edited May 2013
    Circs instead of zone valves

    mainly to provide zone by zone flow control.   If I had CCVs and proportional controls I could use a single ∆P ECM circ, but I might still separate out that 40 GPM zone since it represents almost 2/3rds of the total system flow.  While ECM circs can modulate flow, they are still centrifugal pumps, and as such, pay a price in hydraulic efficiency when operated near the bottom of their range.  What does the giant pump do when only one of those 5 GPM zones is calling?

    Are there additional downstream control valves?
  • Wayco WayneWayco Wayne Member Posts: 2,469
    I was thinking

    Of using the large Wilo for the 15 and 40 and using a smaller circ for the single digit zones. I'll look at the pump curves tomorrow.
  • SWEISWEI Member Posts: 7,356
    That should work

    even with bang/bang zone valves!
  • Check out White Rodgers ZV's

    They are basically a full port design.  The 1 1/4 inch has a lot of flow capacity and are pretty inexpensive.  They are what I used to use whenever I needed a lot of capacity.
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert

    Noisy Radiators are a Cry for Help
  • Wayco WayneWayco Wayne Member Posts: 2,469

    I'll remember that for next time. I've already bought a Belimo with a cv of 57 for a 2" zone valve. Since my gpm is 40 I'm good with that.
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