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Radiant loop flow

2

Comments

  • Unknown
    Unknown


    There is no way this is a pressure drop problem. This pump, with those zones, and this hardware should be pumping a GPM per loop easy on hi speed on that 15-58. Certainly a 26-99 should have, and he tested that too. That main circuit is secondary to the boiler, so boiler pressure drop is not in line, and the main circuit has a pretty negligable pressure drop.

    I'm back to a mystery obstruction. It's the only thing that make sense... something lodged somewhere not in the purge circuit path. unless it's a power issue with the pump's electrical circuit??
  • John M_5
    John M_5 Member Posts: 38


    Thanks,
  • Unknown
    Unknown
    Did you try,

    cranking the mixing valve wide open? Looking at the circuit the only thing I see that could be causing this is an issue with the mix valve unless, as someone else mentioned, you need to power those zone valves to ensure they are full open.
  • George Peteya_5
    George Peteya_5 Member Posts: 9
    Mystery Obstruction

    John,

    I think it's time to disassemble the 3-way valve and see if something got lodged in there. You're running out of places to look/components to blame!

    George
  • John M_5
    John M_5 Member Posts: 38


    I tried putting power the the vales, I even ran a return line from the manifold return back to secondary return and bypassed the zone valve alltogether. also tried the mixing valve wide open.

    At this point I think their is some head loss I'm not accounting for. I going to try resizing the pump in reverse. If i can only get .8 gpm on one loop with the pump I have , I'll assume 19 ft of head and resize acording to that. Thanks to all that replyed, I will post my results.

    John M
  • Unknown
    Unknown


    John, I thought you already tried a 26-99? If that isn't doing it...

    Frankly, I'm really down to a mystery obstruction or a power issue to this pump.
  • Mac_4
    Mac_4 Member Posts: 6
    Circulator point on view

    Ignoring everything in the system but the pump, the symtoms you describe do indicate there could be allot of resistance somewhere in the flow loop. The suggestions so far have focused primarily on this possibility and it is the most likly culprit. Other possibilities could be the power source(voltage)could be wrong or to low, you could be bypassing flow (but your schmatic would not indicate this is a possibility), or the pressure on the suction side of the pump could be very low.
  • John M_5
    John M_5 Member Posts: 38


    I did try the 26-99, but didn't record the numbers. they were only slightly higher. neither pump was wired directly so power could be a ?. But even on high they draw less then 2 amps. I'll try the 26-99 again before I buy anything else. I'm already into this for 8K, don't want to spend more then I have to.

    I blew out all the loops before connecting them, so I fairly sure theat they are clear. I ran the radiant for a while last night, and after about 20 min they all got up to temp. maybe it's just cheap manifolds?
  • John M_5
    John M_5 Member Posts: 38


    with the 15-58 pump, I have 20 psi at the input and about 25-26 psi on the output with all loops open.
  • hot_rod
    hot_rod Member Posts: 23,173
    crud in the check?

    teflon tape, solder flux, and pipe dope can restrict the flow through the intergral checks in the pump.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • George Peteya_5
    George Peteya_5 Member Posts: 9
    Crud

    HR, the obstruction's not in the integral flow check if John changed to a 26-99 (and back). I'd sure like to see what the guts of the 5000 mixing valve look like!

    George
  • Mac_4
    Mac_4 Member Posts: 6
    Flow

    If you are getting 5psi plus (11.5ft plus) accross the 15-58 the curve I'm looking at says its pumping 8 gpm plus on speed 3.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    I say...

    Pull the guts out of everything! The pump, the 3 way valve, and see what you find and see what happens.

    That's what I'd do out of frustration...

    ME

    There was an error rendering this rich post.

  • Rusty Powers
    Rusty Powers Member Posts: 30
    Maybe...

    What is the model # of your Honeywell zone valve?
    Possibly too restrictive, with eveything else in the path.
  • Marc_22
    Marc_22 Member Posts: 3
    aluminum hx

    tubes could be plugged. have already seen it many times from aluminum hx'ers breaking down. going to be a nightmare in a few years.....STAINLESSSSSSSS
  • Unknown
    Unknown
    delta T?

    what is it across the loops? maybe the flow meters are junk and they're giving you bad info?
  • Techman
    Techman Member Posts: 2,144
    low flow

    On one job we cut both supply and return lines of one loop ,and blew thru the pex with 100 psi air, Wham, Bam, the junk flew. We refilled the loop and blew out again but in the opposite direction.Then a garden hose adapted to the pex and flushed and flushed.12 zones produced 1qt of stuff.
  • John M_5
    John M_5 Member Posts: 38


    I don't recall 43?? but the Cv is 3.5
  • John M_5
    John M_5 Member Posts: 38


    Once they heat up 10-15 deg
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    Based on all the data....

    Pressure differential across pump, indicating good flow, and a reasonable delta T, I think maybe the flow meters on the manifolds are fewked.

    As a last positive test, try closing the supply ball valve REAL quick, and see if you hear a hydraulic rush, kind of a SWOOOOssh. If yes, you have flow. If no, or a small swoosh, you have little or no flow. Make sure background noise is at a minimum when doing this test.

    The other method, taught to me by an old solar hippy, is to take a torch, and hold it in one place on the copper pipe. Hold it there for 10 or so seconds. If the pipe starts to change color, there probably is no flow. If there IS flow, within the same amount of time that you held the torch to the pipe, the pipe should be relatively cool to the touch. So, 10 seconds of torch, followed by 10 seconds of waiting, then CAREFULLY (open palmed) touch (tap) the pipe to see if it is hot or not. If its still hot, you've got no flow. If it is relatively cool (heat being washed away by flow) then you have flow.

    Did you gut the 3 way valve yet? It has some pretty tight tolerances that don't tolerate much muck.

    ME

    There was an error rendering this rich post.

  • Unknown
    Unknown
    Delta t,

    sounds right to me. I concur with ME on the effed up flowmeters. Let it rip and see how it works.
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could you try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier). .02 gallons per minute will still heat up a zone, it just run constantly, (assuming you have a poor to midgrade home insulation job installed).
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could you try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier). .02 gallons per minute may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier). .02 gallons per minute may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier) or balanced so every loop flows at the same slow rate at around .05 in your case. Having .02 gallon per minute flow may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute, (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier) or balanced so every loop flows at the same slow rate at around .05 in your case. Having .02 gallon per minute flow may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute, (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier) or balanced so every loop flows at the same slow rate at around .05 in your case. Having .02 gallon per minute flow may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).

    Also radiant rule #6, if all radiant loops in a zone are withen 10% of each other in lenth, then no need for flowchecks, fance headers etc.
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute, (they will). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 260ish' of 1/2" pex pipe on headers with flowchecks. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier) or balanced so every loop flows at the same slow rate at around .05 in your case. Having .02 gallon per minute flow may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).

    Also radiant rule #6, if all radiant loops in a zone/header are withn 10% of each other in lenth, then no need for flowchecks, fancy headers etc.
  • Jeremy_14
    Jeremy_14 Member Posts: 34
    Low Flow

    Hi again John, I left a few posts earlier about your radiant loops maybe being too long which you just sort a shrugged off. Seeing as you have already checked for blockages in the mixing valve and circulator etc. you could try hooking up temporary 3' loops on all 6 radiant lines and see if every loop when calling for heat flows at 1.5 gallons per minute, (they will, unless??). I've installed dozens of systems with a similar or exactly the same layout as yours with radiant loops ranging from 100' to 280'ish of 1/2" pex pipe on 1" headers with flowchecks and 3 to 12 loops. With 1" mixing valves, circulators of several sizes and speeds, the one constant I have noticed is short and long loop lengths have dramatically different flow rates as evidenced by your own description of your "problem". The longer loops will be slower to heat up, you should except that unless you change the way things are piped, (as I suggested earlier) or balanced so every loop flows at the same slow rate at around .05 gpm in your case. Having .02 gallon per minute flow may still heat up a zone in the dead of winter, it just runs constantly, (assuming you have a poor to midgrade home insulation job installed, foam, no problem).

    Also radiant rule #6, if all radiant loops in a zone/header are within 10% of each other in lenth, then no need for flowchecks, fancy headers etc. a dirty little secret no wholesaler wants us to know.
  • John M_5
    John M_5 Member Posts: 38


    Hi Hunter, I called Viega tech support and they seemed to think the loop length was fine. As long as the radius is not less then 10" head loss on the longest loop would be
    6.7 ft
  • George Peteya_5
    George Peteya_5 Member Posts: 9
    3-way valve

    John,

    PLEASE take that Taco 5000 mixing valve apart! The suspense is KILLIN' me! I'd say ME, HR, and NRT.Rob are trying to find their x-ray glasses too!

    George
  • Unknown
    Unknown
    The only problem,,,

    appears to be inaccurate flowmeters. Delta T across the loops, if we have an accurate reading, is right in the ballpark which is a much better indicator of flow than the meters. There seems to be an awful lot of people trying to make an awful lot of extra work for this guy. It would appear some are posting before reading through the entire thread.
  • Joe Mattiello
    Joe Mattiello Member Posts: 718


    John
    The Taco mixing valve doesn't appear to be the hindrance. Perhaps you can call me here at Taco to go over your application.

    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • Unknown
    Unknown
    Joe, go back one post before yours and read mine

    .
  • George Peteya_5
    George Peteya_5 Member Posts: 9
    Delta T

    A 10 to 15 degree delta is a good DESIGN delta. What's the heat load today? Not design load (although I don't know where the job is, John). A 15 degree delta today could be 30 degrees on a design day.

    George
  • Jeremy in DM
    Jeremy in DM Member Posts: 6


    I still contend that the mix valve is not piped correctly. If you look at Taco's installation instructions, they show multiple ways to pipe the mix valve, all showing two tees close together, making the mix zones secondary off of a main loop. Even with the bigger pump, you are now pumping through the entire system, including all high temp zones. i really believe changing the piping of the mix valve will change the way the system behaves.
  • [Deleted User]
    [Deleted User] Posts: 0
    Agreed...

    I see 7 to 10's ALL the time, even at design condition.

    The "real time" load is NO WHERE near as bad as we design for, hence short cycling BANG BANG boilers...

    Thank goodness for modcons :-)

    ME
  • Unknown
    Unknown
    Don't you think,,,

    things like ODT and load should be determined before we go telling him to rip pretty much everything in the system apart? Chances are, while he may not have design load, he probably has a fair amount of load this time of year, unless he's in a warmer part of the US. Plus, I'd be willing to bet he hasn't let the system come up and settle out. Tell us what Delta T and ODT are after it's been running 24/48 hours. Then we'll know more. Wouldn't be the first time inaccurate gauges have sent someone on a wild goose chase.
  • Unknown
    Unknown


    Jeremy: you are totally incorrect in your assessment of this mixing valve. the mix pump is pulling only through the main header.. not through the boiler or any other zones.

    It is possible that the high temp zone pumps COULD "fight" with this pump since they are not hydraulically separated, but no more than they would fight with each other, and if there isn't a dramatic difference in pumping power, it shouldn't be a big deal.

    Further, if that were the problem, it would only show up when the high temp zone pumps were calling. They are off, so that is not the problem.

    If he did that mixing valve primary/secondary, as you suggest, he'd also have to add another pump to the main header to get flow to the tees. This is a more efficient setup, as long as he doesn't get himself into trouble with beefy pumps "shutting down" the smaller pump. and he shouldn't.
  • Unknown
    Unknown


    MPF, what are the chances that every flow meter is bad?

    That's a pretty long shot. Unless they are in backwards, or there is a major water quality issue, or john is reading them wrong.
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