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Big red tank

Tom_133 Member Posts: 884
Good Morning all,

I am being tasked with swapping out an old taco inline pump and replacing it with a new high efficiency.

I want to size the new pump but only know the Indirect is 500 gallons, Taco, ASME, and has 3" inlet on the coil. The old pump which seems oversized due to the delta being 4-5 degrees gives me some hints but not enough.

I would really like to get a pump I can reuse this summer when I replace that big ASME tank with 3 smaller indirects to save the customer some coin.

Anyone know where on the insulation I can cut to find the tag on the tank?

Or the pressure drop through the coil? Which seems unlikely due to the endless possibilities.

Montpelier Vt


  • ScottSecor
    ScottSecor Member Posts: 855
    It would help us identify the existing circulator if you stood back a few feet and shot the veloute/bearing assembly.

    I'm guessing the original designer wanted to transfer the energy to the tank real fast as DHW demand often needs to met almost instantly. Without more data, my guess is the pump is a Taco model 1612? This data sheet may help.
  • Big Ed_4
    Big Ed_4 Member Posts: 2,785
    Call TACO (401) 942-8000
    I have enough experience to know , that I dont know it all
  • SteveSan
    SteveSan Member Posts: 234
    Hi Tom, If the number on the casing is 1614-020 is correct and you have a 1/2 HP motor it's either a 1612 or 1615 pump. Please call into Taco Tech Support 401-942-8000 we are here Mon-Fri 8AM to 5PM EST.
  • Zman
    Zman Member Posts: 7,569
    It would help to know the model of the indirect coil. From there you will know required flow rate and head loss.
    There is usually either a plate on the face of the coil or on the edge where it mates to the tank.
    You are wise to suspect the pump is oversized. It is better to check the math than to just replace 1 for 1.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Tom_133
    Tom_133 Member Posts: 884
    Well guys, I heard back from Taco, and they feel the same as me, I can probably throw a VR15 in and set it to what I want it to do for me. When I pull that big monster tank I will take a pic of the tag after I strip the insulation and update this post. But dont wait up, probably 3-4 months away. Thanks
    Montpelier Vt
  • hot_rod
    hot_rod Member Posts: 22,146
    probably work backwards, 3" coil 1/2 hp circulator, that would give you some idea of possible flow rate.

    Don't get hung up on delta, it could start wide with a cold tank, and close down as the tank approaches set point. Hot to cold, rate of transfer is, has to be, ∆T driven.

    An example of why you would not want to run a constrained T pump. Let the ∆ move. ∆T is an indication of heat transfer.

    Watch how a wood boiler heats a buffer, or an indirect heating up, big gains on a cold tank, the last 10- 15° seems to take forever. ∆ closes, rate of transfer slows.

    This applies to tanks, fin tube, radiant loops, air coils, even air to air, really any heat transfer.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream