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circulator vs zone valve

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Superchief
Superchief Member Posts: 4

I am the builder on a luxury residential project. For hydronic radiant I was anticipating 1 variable speed circulator = 1 zone = 1 sub-manifold which my plumber also prefers, but the MEP designing the system things using 1 larger circulator and zone valve = sub manifold is a better solution. My priority is reliability, then efficiency, then price … all circulators would be top of the line either way but I have seen a lot of zone valves fail and I have yet to see a circulator fail though undoubtedly they do - informed opinions on the best practice if price is not an issue are appreciated.

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  • Intplm.
    Intplm. Member Posts: 2,083
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    If that's the case as you describe. A good circulator is your best bet. One circulator dedicated for each zone with its own dedicated thermostat.

    delcrossvDerheatmeister
  • GroundUp
    GroundUp Member Posts: 1,955
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    Circulator vs zone valve is entirely up to the system itself- there is no "one size fits all" answer for a question like that. However, what you actually typed out as the question, isn't asking for a zone circ vs zone valve comparison. What exactly are you asking? More information is needed to gather an educated opinion on this topic. Anybody who says one or the other without knowing all the specifics is not using any education to make that call.

    TeemokDerheatmeister
  • Teemok
    Teemok Member, Email Confirmation Posts: 562
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    The best cast iron circulator can be ruined by poor system design or maintenance, while 30 good zone valve would be unaffected. Reliability is in the many details. Clean treated water that is 100% contained is a key. Stainless pumps are the way to go if cost is not a thing. The variable speed ability means one pump and many zones is possible and efficient. Eliminating zone valves and setting a single pump speed is just an ecm pump not a true variable speed pump. If efficiency is not a care and there's not a ton of zones, individual non ecm pumps would be very reliable.

  • jumper
    jumper Member Posts: 2,331
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    ditto. Just make certain that circulators are not over-sized and choose one with curve that matches circuit, foot per second wise.

    Intplm.
  • HomerJSmith
    HomerJSmith Member Posts: 2,511
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    "hydronic radiant", I assume is in floor tubing with many loops. I am constrained by lack of information on your project. So much goes into choosing a proper course of action and you haven't provided that information.

    Add up the cost for both sys and factor in the yearly energy costs to find the economical solution. Today zone valves are pretty reliable. I like Taco Sentry ZVs or Caleffi's. With multiple manifolds and ZVs an ECM pump is a do. You always have to keep in mind flow rates and control.

    PC7060
  • Superchief
    Superchief Member Posts: 4
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    Teemok when I said ECM I meant variable speed ECM where each is sized for each manifold which the MEP will do…. sorry for the confusion. So I am thinking individually sized pumps 1 per zone but the MEP is recommending 1 larger VSP and then zone valves. The thing is he does a lot of "for bid" system design where his customer wants the lowest cost to win the bid … I do know that in our area I see a lot of system with all circulators and always believed it to be more reliable for a small upfront cost, but I don't know that they are more reliable though I do know I've had a lot of zone valve failures in my personal experience but i didn't build my house and don't think highly of the plumber, so perhaps it was just done badly ?

    Follow up question - anyone have experience with AquaMotion circulators? I have always used Grundfos or Taco but my plumber suggested the MEP look at them and their curves, I never heard of them.

  • Teemok
    Teemok Member, Email Confirmation Posts: 562
    edited July 10
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    @Superchief I should add to my previous comment: Stainless pumps only make sense if your whole system has no Iron in it, completely ferrous free. There's not much point in a stainless pump if your boiler is cast iron or you have steel radiators or old steel piping or any iron in the system at all. Iron oxides and ECM pumps don't play well. Some (cheaper) Ecm pumps are 3 speed only. They are good pumps for what you are talking about. Using zone valves is more in line with using a larger true variable speed ecm pump. It can operate on along a continuous curve responding to a signal to tightly control speed between a min and max. The signal could be a desired pressure, flow or temperature. There are zone valves that have bad reputations. Failures can be a pain and costly if your dealing with many. Caleffi makes a solid valve that is guts rebuild-able with an actuator top that is easily swapped. Their end switches were a flaw many years ago but the updated fix is good.

    This is a debate that pros go back and forth on into the night. Well installed quality valves can be as trouble free as pump only. Theoretically valves can be more efficient. Distribution piping can be cheaper with valves over individual pumps in large buildings. What to use is a whole picture perspective good designer question.

  • GroundUp
    GroundUp Member Posts: 1,955
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    Again, some information is needed. Is this a 1 zone radiant floor system or a 20 zone baseboard system? What is the water temp? What type of heating appliance will be used? What is the BTU load of each zone? Nobody can make an educated depiction without all of that information.

    With that said, a multi zone system is almost always more reliable when zone valves are properly installed with a single circulator. Zone circs may prove to be easier and more adaptable to an otherwise poorly installed system, but there is a reason that 99% of commercial hydronics are done with some sort of actuator rather than zone circulators.

  • hot_rod
    hot_rod Member Posts: 22,468
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    zone valves with a delta P circulator is a good way to assure zones always get the required gpm. And they save energy being ecm

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jumper
    jumper Member Posts: 2,331
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    Zone valves are on/off control. Is that ideal for radiant?

  • hot_rod
    hot_rod Member Posts: 22,468
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    I don’t see it as a question of “best practice” as much as personal preference.

    15-20 years is reasonable from a zone valve or circ. Caleffi cycle tests to 100,000 cycles on the z-one valve. 5000 cycles per yesr is a realistic number.

    Proper application helps, prevent short cycle, clean fluids .

    I like TRVs best, non electric proportional control.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Derheatmeister
    Derheatmeister Member Posts: 1,572
    edited July 10
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    Here is the european way: »»>One««« Delta T /Delta P or a combination thereof circulating pump with TRV's or Zonevalves…Handsdown very easy and efficient.😊

    System design with single temp is also a benefit.

  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    Nowadays they are very much so modulating base on the homes requirements!

  • Derheatmeister
    Derheatmeister Member Posts: 1,572
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    Nowadays they are very much so modulating base on the homes requirements!

  • HVACNUT
    HVACNUT Member Posts: 5,887
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    One circulator per radiant loop? More info needed. Like the whole layout.