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MonoFlow & Pump Help

Bostopa
Bostopa Member Posts: 3
in THE MAIN WALL

Hi all…back on after a few years.

So, have a B&G monoflo system with convectors…2nd floor get warm not bad first floor better…one loop for 1st & 2nd floor one pump and its a Grundfos 3 speed 15-58 pump.

So, on 2nd floor removed convenctor and installed a B&G Thermoflo Balancer wanted to see what the flow was. And what did I see…sero reading on the Thermoflo. The left side of pipe is getting hot as is the right side. Ok, so maybe the Thermoflo is stuck…removed it went to the facet put water throw it and it's working.

So, is the 15-58 pump just to small a pump for a monoflo system?

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Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,183

    Chances are its fine. Monoflow systems are absurdly sensitive to flow restrictions, and the water is probably just saying that that's more restriction than I like and bypassing…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bostopa
    Bostopa Member Posts: 3

    Thanks Jamie,

    But that answer doesnt really make a lot of sense to me…the 2nd floor is a bit colder, monoflo's have greater restriction and the gauge should show some kind of flow and shows zero. That does not imply fine to me.

    I assume there needs to be a larger pump installed versus the existing 15-58

  • delcrossv
    delcrossv Member Posts: 917
    edited October 17

    One pump for both floors? Zoned or all together?

    The ones I've seen usually have B&G 100's on them. Low head, but high volume.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • LRCCBJ
    LRCCBJ Member Posts: 242
    edited October 17

    A monoflo system suffers from a relatively huge pressure drop at every diverter tee. The real question is whether they piped the system with 1" with either 3/4" or 1/2" takeoffs for the rads or whether they piped it in 3/4" with 1/2" takeoffs?

    I can tell you from experience that the latter setup will never offer a sufficient flow rate with any of the Taco 00 pumps. I installed a Taco 011 and the system still cannot get below a DT of 27F. The Cv is just too great from the sum of six monoflo tees and the resulting flow rate is too low. The last two rads on the loop have severely diminished performance.

  • Bostopa
    Bostopa Member Posts: 3

    Hi DelcrossV…a few years back it did have a 100 on it…it was suggested to put a smaller 15-58 in there. But I still have the 100 and it was in real good shap…maybe I put that in there as a test. And yes one pump both floors its one loop.

    LRCCBJ…so it's 11/4" main line comming off boiler goes down the middle of basement when it reaches farthest wall it branches off left and right to 1" lines. Each of those lines has the diverter tees which are 1" and the convectors are 1/2" going to them. So, each convenctor has a 1" monflo tee and the 1/2" pipe goes right to the convenctor. They are all like that.

    delcrossv

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