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Can a Taco Bumblebee

ced48
ced48 Member Posts: 469
be set to maintain a minimum pump speed? I see nothing in the manual that addresses this.

Comments

  • Rich_49
    Rich_49 Member Posts: 2,766
    Bumble Bee

    will maintain a set point , Delta T, or constant power (set speed) . It will operate at which one of 4 speeds you want it to in CP mode . Just program it to your conditions .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • ced48
    ced48 Member Posts: 469
    I Got That, But

    how about Delta-T, but with a set minimum operating percentage, like other Taco variable speed pumps?
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Pump Is Going

    Operate on its curve just like any other pump when put in a fixed speed mode. You cannot fix the pump speed. Why would you want a fixed speed?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ced48
    ced48 Member Posts: 469
    The Reason Is-

    I am piping direct, no prim/sec, a modcon and I would like to be able to use the variable speed feature to maintain Delta-T, but I also must be sure of always having a certain minimum flow thru the boiler. so I thought I could set the pump to always maintain a certain percentage output, and let it do what it wanted, as long as it maintained the preset minimum.
  • SWEI
    SWEI Member Posts: 7,356
    Boiler minimum flow rate

    Is specified at high fire.  If you run the pump ∆T it will track the boiler output so you don't actually have to worry about minimum flow.  If the boiler goes off on limit, you will know you got something wrong -- might have to dial back the ∆T 5F or so, but not any kind of a safety risk.
  • Rich_49
    Rich_49 Member Posts: 2,766
    edited July 2013
    Ced48

    What boiler are you proposing this piping arrangement for ?  What type of emitters will you be using also ?
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited July 2013
    Yuppers

    Kurt the other thing direct pipers forget is as they increase system head they reduce the gpm flow across the boiler, thus increasing the needed delta-t to get full output.. Minimum on a PT110 is 5.5gpm to get the full output at high fire. That would mean you were running your system on a 35 Degree Delta-T. How many guys do ya think understand that?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Rich_49
    Rich_49 Member Posts: 2,766
    Not Enough

    of em Chris !  Why would you increase a header that must be 1 1/4 to  1 1/2 " ?  That would cost 100.00 , we can't do that !  I think it's part of the design as you solder syndrome.
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • ced48
    ced48 Member Posts: 469
    A lochinvar WH 55

    limited to 70% on the heating side, 75 feet of Slant Fin baseboard. Split loop system, with about 6 feet of head, 2- 90 foot sections. Heat loss around 30,000, or less-
  • Rich_49
    Rich_49 Member Posts: 2,766
    WH55

    does give the installer the option of using a var. spd.  pump for the boiler .  At 20 Delta literature says  3 GPM .27' , Yeah the bumble bee will do that @ 9 watts .  Make sure about your direct piping , they do recommend Pri / Sec in the Notices ( pg 37) .  Have you thought of the CDN040 (cadet boiler) ?  Smaller BTU , closer to your 30K required . 
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • SWEI
    SWEI Member Posts: 7,356
    CDN040

    Also a lower minimum firing rate (9k versus 11k) and about 30% less cost.
  • ced48
    ced48 Member Posts: 469
    I Don't Like the-

    HX on the Cadet-bought the Lochinvar for a couple of hundred dollars more-beter computer too- As far as prim/sec, Locvinvar is okay with it-does not void warrantee. I can't see spending $400+ on a circulator when a $175 will the same thing, more or less. Thanks for the suggestions, though.
  • ced48
    ced48 Member Posts: 469
    I Mean Lochinvar-

    is okay with directing piping on a small system like this, as long as I provide the required minimum boiler flow-
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited July 2013
    Required Minimum Flow

    Is what is needed when you need the full btu/hr output of the boiler. If you don't need it then its not required. As long as you maintain the flow needed at the minimum modulation rate then your ok.. You'll be at the minimum end of the modulation rate much more then you will ever need the max end of the modulation rate.



    When direct piped the only thing that can change the pump flow is the pressure drop or ft of head in the system. I believe you said 6' of head. So pick up a pump that will move the required flow based from your heat loss. If the boiler is 55,000 and the loss is only 30,000 why would you ever need the full out/put of the boiler?



    On over sized pump is just going to reduce your system/boiler delta-t which could lead to boiler short cycling.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ced48
    ced48 Member Posts: 469
    Yes, About 6 Feet

    of head-So, I will be just fine letting the Bumblebee maintain a 20 degree Delta-T? Sounds like the boiler will shut down if minimum flow is not being achieved, requiring a differential adjustment to the Delta-T. I also just realized that the pump will give me a wattage usage readout, so I'll know how much of the pump's capacity is being used. Taco warns that the GPM readout is less than accurate, so I can't go by it. Using never more than 70% of the boiler;s capacity, required flow should be minimal. I'll bet I'll be running at 35% or so most of the time. Prim/sec just seems silly in my case-
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Minimum OutPut of the Boiler Is What?

    There's your minimum flow..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ced48
    ced48 Member Posts: 469
    Minimum Output -

    about 9, minimum input is 11- So are you saying if the flow drops, the boiler will modulate down to be inline with that flow rate? I am trying to learn all I can, not just install a system that works and not know how or why it works. I appreciate your help, Chris, and all the rest of you who have made suggestions.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Boiler Doesn't Modulate on Flow

    Modulates base on delta-t....flow carries btu/hr based on that delta-t..



    Inutput is 11,000 btu/hr - You'd need to move 1.1gpm at low fire on a 20 degree delta-t. Flow kills you when you cannot move the btu/hr being created in the HX/Boiler out of it. You could then flash to steam.



    This isn't anything new. It's done everyday across the pond with boiler pumps controlled by the boilers control logic to match pump flow to the modulation rate.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
This discussion has been closed.